Liebert Challenger 3000 Users Manual

3000 to the manual ec2d4dbc-4266-4eb8-a172-699ca04c5725

: Liebert Liebert-Challenger-3000-Users-Manual-571306 liebert-challenger-3000-users-manual-571306 liebert pdf

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Precision Cooling
For Business-Critical Continuity

Liebert Challenger™ 3000
Operation & Maintenance Manual - 3 & 5 Ton, 50 & 60Hz

TABLE OF CONTENTS
1.0

INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

1.1

System Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1.1
1.1.2
1.1.3

Compressorized Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
GLYCOOL™ (Chilled Glycol Cooling) Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Chilled Water Systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.2

Start-Up Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2.0

OPERATION WITH ADVANCED MICROPROCESSOR CONTROLS . . . . . . . . . . . . . . . . . . . . . . .3

2.1

Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2.2

Status Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2.3

Main Menu  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2.4

Status/Alarm Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.4.1
2.4.2
2.4.3
2.4.4
2.4.5

2.5

Active Alarms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operating Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Alarm History Log . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Run Hours Log . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Analog Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5
5
5
6
6

Setpoints/Setup. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.5.1
2.5.2
2.5.3
2.5.4

View Setpoints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Setup System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Run Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Change Passwords . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

2.6

Date and Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

2.7

Status Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

2.8

Control Circuit Board. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.8.1
2.8.2
2.8.3
2.8.4

LCD Display Contrast . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Non-Volatile Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DIP Switches. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Control Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

13
14
14
14

3.0

OPERATION WITH ADVANCED MICROPROCESSOR WITH GRAPHICS CONTROL . . . . . . . . . . . 15

3.1

Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

3.2

Status Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

3.3

Main Menu  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

3.4

View/Set Alarms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
3.4.1
3.4.2
3.4.3
3.4.4
3.4.5
3.4.6

Active Alarms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Alarm History Log . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setup Alarms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setup Custom Alarms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
View Water Detect Floor Plan (for Optional LTM1000/LT750). . . . . . . . . . . . . . . . . . . . . . . .
Setup Water Detect Floor Plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

17
17
18
19
19
19

3.5

Operating Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

3.6

View/Set Control Setpoints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

3.7

System Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
i

3.7.1
3.7.2
3.7.3
3.7.4
3.7.5
3.7.6
3.7.7
3.7.8

3.8

Setup Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Select Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Calibrate Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Calibrate Valve Actuator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Select Control Algorithm (Chilled Water and SCR Reheats only). . . . . . . . . . . . . . . . . . . . . .
Select Humidity Sensing Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Set Status Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Change Passwords . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

20
22
22
22
22
23
23
23

Run Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
3.8.1
3.8.2
3.8.3
3.8.4

Show Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Test Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Test Control Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DIP Switches. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

24
24
24
25

3.9

Date and Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

3.10

Plot Graphs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
3.10.1 Modify Plot Scales . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

3.11

Analog/Digital Inputs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
3.11.1
3.11.2
3.11.3
3.11.4

3.12

Read Analog Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setup Analog Inputs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Read Digital Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setup Digital Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

26
26
26
26

View Run Hours Log . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
3.12.1 View 24 Hour Run Time History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
3.12.2 View Total Run Hours . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

3.13

Control Circuit board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
3.13.1
3.13.2
3.13.3
3.13.4

LCD Contrast . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Nonvolatile Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DIP Switches. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Control Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

27
28
28
28

4.0

SYSTEM PERFORMANCE WITH ADVANCED MICROPROCESSOR CONTROLS . . . . . . . . . . . . . 29

4.1

Temperature Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
4.1.1
4.1.2
4.1.3
4.1.4

4.2

Dehumidification/Humidification Required, in Percent. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Response to Control Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Dehumidification Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Humidification Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

31
31
31
32

Control Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
4.3.1
4.3.2
4.3.3

4.4

29
29
30
31

Humidity Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
4.2.1
4.2.2
4.2.3
4.2.4

4.3

Cooling/Heating Required, in Percent (%) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Response to Control Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cooling Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Heating Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Proportional Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
PID Control (Chilled Water or SCR Reheats only). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Intelligent Control (Chilled Water only) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Load Control Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
4.4.1

Short Cycle Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

ii

4.4.2

4.5

Sequential Load Activation Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Additional Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
4.5.1
4.5.2

Connecting the Analog Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Water Detection Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

4.6

Communications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

5.0

ALARM DESCRIPTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

5.1

Standard Alarms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
5.1.1
5.1.2
5.1.3
5.1.4
5.1.5
5.1.6
5.1.7
5.1.8
5.1.9
5.1.10
5.1.11
5.1.12
5.1.13
5.1.14
5.1.15
5.1.16

5.2

Change Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Compressor Overload . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Custom Alarms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
High Head Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
High Humidity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
High Humidity and Low Humidity (Simultaneously) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
High Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
High Temperature and Low Temperature (Simultaneously) . . . . . . . . . . . . . . . . . . . . . . . . .
Humidifier Problem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Loss of Air Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Loss of Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Low Humidity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Low Suction Pressure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Low Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Main Fan Overload. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Short Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

38
39
39
39
39
39
39
40
40
40
40
40
40
40
40
41

Optional/Custom Alarms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
5.2.1
5.2.2
5.2.3
5.2.4
5.2.5

Loss of Water Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Smoke Detected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Standby GC Pump On . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Standby Unit On. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Water Under Floor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

41
41
41
41
41

6.0

COMPONENT OPERATION AND MAINTENANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

6.1

System Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

6.2

Filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

6.3

Blower Package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

6.1.1

6.3.1
6.3.2
6.3.3

6.4

Environmental Control Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Fan Impellers and Bearings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Belt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Air Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Refrigeration System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
6.4.1
6.4.2
6.4.3
6.4.4
6.4.5
6.4.6
6.4.7
6.4.8
6.4.9

Suction Pressure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Discharge Pressure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Superheat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Thermostatic Expansion Valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Hot Gas Bypass Valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Air Cooled Condenser . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Water/Glycol Cooled Condensers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Compressor Functional Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Compressor Replacement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
iii

46
46
46
47
47
48
49
51
51

6.5

Humidifier. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
6.5.1
6.5.2

Infrared Humidifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Steam Generating Humidifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

7.0

TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

8.0

MONTHLY MAINTENANCE INSPECTION CHECKLIST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

9.0

SEMIANNUAL MAINTENANCE INSPECTION CHECKLIST . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

iv

FIGURES
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8
Figure 9
Figure 10
Figure 11
Figure 12
Figure 13
Figure 14

Advanced microprocessor control panel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Advanced microprocessor (A) control for Challenger 3000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Advanced microprocessor with graphics (G) control panel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Advanced microprocessor with graphics control menu. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Analog input jumpers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Connecting the LT750. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Liebert leak detection units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Recommended liquid sensor locations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Outdoor fan/condenser configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Johnson Controls valve adjustment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Metrex valve adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Infrared humidifier lamps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Steam generating humidifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Canister replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

TABLES
Table 1
Table 2
Table 3
Table 4
Table 5
Table 6
Table 7
Table 8
Table 9
Table 10
Table 11
Table 12
Table 13
Table 14
Table 15
Table 16
Table 17
Table 18
Table 19
Table 20
Table 21
Table 22
Table 23
Table 24
Table 25
Table 26
Table 27
Table 28

Default setpoints and ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Setup functions, default values and ranges. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Unit options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
DIP switch settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Alarm default time delays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Control output LEDs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Alarm default time delays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Default setpoints and ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Setup functions, default values and ranges. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Unit options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Setting options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Control output LEDs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Cooling/dehumidification load status response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Analog input terminals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Additional connections available after unit delivery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Zone leak detection kit installation scenarios . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Recommended free area ft2 (m2) for grilles or perforated panels at output velocities
of 550 and 600 fpm (2.8 and 3.1 m/s) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Suction pressures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Discharge pressures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Humidifier canister part numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Blower troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Chilled water troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Compressor and refrigeration system troubleshooting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Dehumidification troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Glycol pump troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Infrared humidifier troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Steam generating humidifier troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Reheat troubleshooting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

v

vi

Introduction

1.0

INTRODUCTION

1.1

System Descriptions
Challenger 3000™ Liebert environmental control systems are available in several configurations.
Each configuration can operate with either Advanced Microprocessor Controls (A), or Advanced
Microprocessor Controls with Graphics (G). A brief description of each, including operational differences, are listed below. Check model numbers to see what is supplied with your unit.

1.1.1

Compressorized Systems
NOTE
Compressorized systems may be a self-contained system – with the compressor in the
Challenger 3000 unit, or a split system – with the compressor in the separate condensing unit.
These systems may be air, water, or glycol cooled, depending on the heat rejection method selected.
Cooling—One stage standard; two stages of mechanical refrigeration with optional split coil.
Heating—Two stages of electric reheat standard; SCR controlled electric reheat, hot water reheat,
hot gas reheat on water and glycol cooled systems optional.
Humidification—Infrared standard; steam generating optional.
Dehumidification—Hot gas bypass locked out standard; part coil operation optional

1.1.2

GLYCOOL™ (Chilled Glycol Cooling) Systems
GLYCOOL™ systems have all of the features of a compressorized water or glycol system, plus a second cooling coil that is connected into the water circuit. When fluid temperature is sufficiently low
(below room temperature), cooling is provided by circulating the fluid through the second cooling coil
(flow is controlled by a motorized valve.) This is then the primary cooling source and it greatly
reduces the compressor operation.
Cooling—Modulated cooling valve opens proportionally to match room needs (primary), one or two
stages of mechanical refrigeration (secondary)
Heating—Two stages of electric reheat standard
Humidification—Infrared standard; steam generating optional
Dehumidification—Hot gas bypass locked out standard

1.1.3

Chilled Water Systems
These systems utilize a central chiller and control cooling by modulating a control valve in the chilled
water line.
Cooling—Proportional in response to room needs
Heating—Two stages of electric reheat standard
Humidification—Infrared standard; steam generating optional
Dehumidification—Chilled water valve opens proportionally in response to room needs

1

Introduction

1.2

Start-Up Procedure
Before beginning start-up, make certain that unit was installed according to the instructions in the
Installation Manual. Verify that the fan shipping bolt has been removed, the check valve has been
installed (on air cooled units), and that the scroll compressor is rotating in the proper direction. All
exterior panels must be in place with the front panel open.
Locate the start-up form supplied with your unit documents. Complete the form during your start-up
and mail it to Liebert when start-up is completed. Contact your Liebert supplier if you have any questions or problems during your unit installation, start-up, or operation.

!

WARNING

Potentially lethal voltages exist within this equipment during operation. Observe all cautions
and warnings on unit and in this manual. Failure to do so could result in serious injury or
death. Only qualified service and maintenance personnel should work with this equipment.

1. Disconnect all power to the environmental control unit.
2. Tighten all electrical wiring connections that may have loosened during shipping (on electric
panel and at all major components, such as compressor, reheats, humidifier and motor).
3. Remove all line voltage fuses except the main fan fuses at the far right of the electric panel and
the Control Voltage fuses at the far left of the electric panel. For units supplied with circuit
breakers, open them instead of removing fuses.
4. Turn on power and check line voltage on main unit disconnect switch. Line voltage must be
within 10% of nameplate voltage.
5. Turn ON main unit disconnect switch and check secondary voltage at transformer T1. Voltage at
T1 must be 24 VAC ±2.5 VAC (check at TB1-1 and TB1-8). T1 voltage must not exceed 28 VAC.
Change primary tap if necessary.
6. Push ON button. Blower will start.
7. If you do not want your unit to operate at factory default settings, set temperature and humidity
setpoints and sensitivity, alarms, and other control functions. Refer to 2.0 - Operation with
Advanced Microprocessor Controls or 3.0 - Operation with Advanced Microprocessor
with Graphics Control.
8. Stop unit by depressing ON/OFF button on the front display. Turn OFF main unit disconnect and
main breaker.
9. Replace all fuses (or reset circuit breakers) that were removed in Step 3.
10. Restore power to unit; turn ON the main unit disconnect switch.
11. Push ON button - putting the unit into operation.
12. Check the current draw on all line voltage components and match with serial tag.
13. Verify that the scroll compressor is rotating in the proper direction.

!
14.
15.
16.
17.
18.

CAUTION

The scroll compressor must rotate in the proper direction. Rotation in the wrong direction
will result in poor performance and compressor damage.
Check for unusual noises and vibration.
Check all refrigerant and fluid lines for leaks.
Test all functions of your unit for proper operation.
Close high voltage dead front cover and latch.
Close front accent panel and latch.

Return completed start-up form to:
Liebert Corporation
Warranty Registration
1050 Dearborn Drive
P.O. Box 29186
Columbus, OH 43229
2

Operation with Advanced Microprocessor Controls

2.0

OPERATION WITH ADVANCED MICROPROCESSOR CONTROLS
The advanced microprocessor (A) control for your Liebert Challenger 3000 unit features an easy-touse menu driven LCD display. The menus, control features, and circuit board details are described in
this section. For more control details, refer to 4.0 - System Performance with Advanced Microprocessor Controls, and for more alarm information, refer to 5.0 - Alarm Descriptions.

2.1

Basics
Control keys include ON/OFF, Menu/ESCape, Enter, Increase (UP) arrow, and Decrease (DOWN)
arrow. Refer to Figure 1. These keys are used to move through the menus as prompted on the LCD
display (refer to Figure 2).
To turn the unit ON, press the ON/OFF key after power is applied. To turn the unit OFF, press the
ON/OFF key before power is disconnected.
Active alarms are displayed on the LCD screen. Alarms are also annunciated by an audible beeper. To
silence an alarm, press the ENTER key as prompted on the display. The unit stores the 10 most
recent alarms for review.
Setpoints, DIP switch settings, and other selections were made on your unit before testing at the factory. Setpoints were chosen based on typical operating experience. Other selections were made based
on options included with your unit. Make adjustments to the factory default selections ONLY if they
do not meet your specifications. When entering setpoints, time delays, etc., the allowable ranges are
displayed and may require a password, if enabled.

Figure 1

Advanced microprocessor control panel

3

Operation with Advanced Microprocessor Controls

Figure 2

Advanced microprocessor (A) control for Challenger 3000
Normal Display

Main Menu

72°F 50%RH
Cooling
Dehumidifying
No Alarms Present

Status/Alarm Data
Setpoints/Setup
Date and Time
Status Display

Status Alarm Data

Setpoints/Setup
View Setpoints
Setup System
Run Diagnostics
Change Passwords

Active Alarms
Operating Status
Alarm History Log
Run Hours Log

Active
Alarms

Alarm
History Log

Operating
Status

Run
Hours Log

No Alarms Present

Alarm History Log

OR
Alarm 01 of 01
High Head PR
Use / to Scroll

Alarm 01 of 03
15-APR 09:20:45
High Humidity
Use / to Scroll

Analog
Sensors

View
Setpoints

Analog Sensors
Analog in 1 (2,3,4):xx
AD #1 (2,3,4)
Use / to Scroll
ESCape to exit

Date and Time

Status Display

15-APR-2004 09:30:00

75°F 59%RH
Cooling
Dehumidifying
No Alarms Present

ENTER to change
ESCape to exit

Setup
System

Run
Diagnostics

Change
Password

Run Diagnostics
Show Inputs
Test Outputs
Test Control Board
Setup System

Operating Status
DX Cool
Heat
Econo Cool
CW Valve
DX Deh / Hum

%
%
%
%

Run Hours Log
Comp
GLYCOOL** or CW Coil**
Fan
Hum
RH1
RH2
View Setpoints

Alarms Available
Standard Alarms
Humidifier Problems
High Head Pressures
Change Filter
Loss of Air Flow
High Temperature
Low Temperature
High Humidity
Low Humidity
Short Cycle
Low Suction Pressure
Compressor Overload
Loss of Power
Custom Alarms 1 to 4
Programmed Alarm Messages
Water Under Floor
Smoke Detected
Standby GC Pump On
Loss of Water Flow
Standby Unit On
User Customized Alarm Messages
Available for Custom Alarms

Temp Setpoint
Sensitivity
Hum Setpoint
Sensitivity
High Temp
Alarm
Lo Temp Alarm
High Hum Alarm
Lo Hum Alarm

* Some alarms require optional equipment
** Optional

4

Setup Operation
Cold Start TD
Restart TD
IR Fill Rate
F/C Degrees
Min CW Temp**
CW/HW Flush**
Select Options
Heating
Humidifier
Dehumidifier
Heat Stages
Calibrate Sensors
Show DIP Switches (1-7)
Select Control Type
Intelligent
Proportional
Tunable PID
Proportional Gain
Derivative Gain
Integral Gain
Setup Alarms
Set Time Delays
Enable Alarms
Enable Common Alarm
Set Custom Alarm
Select Alarm
Change Custom TXT 1,2
Hum Control Method
Relative
Absolute
Analog Setup
A/D Input 1 (2,3,4)
Slope
Text
Intercept
Set Status Display
Calibrate Actuator

Change Password
Setpoint Password
Setup Password

Operation with Advanced Microprocessor Controls

2.2

Status Display
The display normally shown includes the present room temperature, humidity, active status functions (cooling, heating, dehumidifying, humidifying), and active alarms. If no keys are pressed within
5 minutes, the system automatically returns to the Status Display. The Status Display may also be
selected from the Main Menu.

2.3

Main Menu 
Press the MENU/ESC key to display the Main Menu. The Menu selections include:
•
•
•
•

2.4

Status/alarm data
Setpoints/setup
Date and time
Status display

Status/Alarm Data
Selecting STATUS/ALARM DATA from the Main Menu will display the following selections:
•
•
•
•
•

2.4.1

Active alarms
Operating status
Alarm history log
Run hours log
Analog sensors

Active Alarms
This screen displays any active alarm. The alarms are numbered, #1 being the most recent. If there
are no active alarms, then “NO ALARMS PRESENT” will be displayed.

2.4.2

Operating Status
The Operating Status is intended to provide the user with displayed information concerning what the
control is calling for the system to do.
NOTE
There may be some time lapse before a specific component matches the displayed number.
For example: The display indicates the chilled water valve is 68% open. On a new call for cooling, it
takes several seconds for the valve to travel from fully closed to 68% open. So, when the display reads
68%, it may take a few seconds for the valve to actually open 68%. Also, if the display indicates a compressor is operating but the compressor has not yet turned on, it may be off because of the short cycle
control (see 4.4.1 - Short Cycle Control).

2.4.3

Alarm History Log
A history of the 10 most recent alarms is kept in nonvolatile memory complete with the date and time
that the alarms occurred. The first alarm in the history is the most recent and the 10th is the oldest.
If the alarm history is full (10 alarms) and a new alarm occurs, the oldest is lost and the newest is
saved in alarm history location 1. The rest are moved down the list by 1. Alarm history on new units
may show the results of factory testing.

5

Operation with Advanced Microprocessor Controls

2.4.4

Run Hours Log
The total operating hours of all major components in the unit can be monitored from the display and
are retained in nonvolatile memory. Run times are available for the following:
•
•
•
•
•
•

Compressor
GLYCOOL Coil (or CW Coil as used on Dual Cooling Unit)
Fan
(HUM) humidifier
(RH1) reheat 1 (or Hot Water or SCR Reheat)
(RH2) reheat 2

The component run hours for each individual component can be reset by selecting the run hours display screen for the desired component, then pressing ENTER within 5 minutes of applying power to
the control. The user will then be prompted to press ENTER to clear the selected component's run
hours.
NOTE
Run hours for a component should be reset ONLY when the component has been replaced.

2.4.5

Analog Sensors
The four (4) analog sensor inputs can be monitored from the display. The inputs are filtered, then displayed along with the text label assigned during setup. See Analog Setup on page 11.

2.5

Setpoints/Setup
Selecting Setpoints/Setup from the Main Menu will display the following selections:
•
•
•
•

View setpoints
Setup system
Run diagnostics
Change passwords
NOTE
Setpoints and system setup parameters are kept in nonvolatile memory.

2.5.1

View Setpoints
Control and alarm setpoints can be reviewed and/or changed through the display. The following table
lists the default setpoints and their allowable ranges.
Table 1

Default setpoints and ranges
Setpoint

Default

Range

Temperature Setpoint

72°F

40 to 90°F (5 to 32°C)

Temperature Sensitivity

2.0°F

1 to 9.9°F (0.6 to 5.6°C)

Humidity Setpoint

50%

20 to 80% RH

Humidity Sensitivity

5%

1 to 30% RH

High Temperature Alarm

80°F

35 to 95°F (2 to 35°C)

Low Temperature Alarm

65°F

35 to 95°F (2 to 35°C)

High Humidity Alarm

60%

15 to 85% RH

Low Humidity Alarm

40%

15 to 85% RH

6

Operation with Advanced Microprocessor Controls

2.5.2

Setup System
The Setup System menu includes the following selections:
•
•
•
•
•
•
•
•
•
•

SETUP OPERATION
SELECT OPTIONS
CALIBRATE SENSORS
SHOW DIP SWITCHES
SELECT CONTROL TYPE (Chilled Water or SCR Reheats only)
SETUP ALARMS
HUM CONTROL METHOD
ANALOG SETUP
SET STATUS DISPLAY
CALIBRATE ACTUATOR

Setup Operation
The Setup Operation menu permits the review and/or adjustment of the unit configuration. This may
include:
Cold Start—This feature, also referred to as Positive Start or Winter Start Kit, allows for the low
pressure switch to be ignored for the programmed time during a cold start of the compressor. Entering a “0” for this time will bypass this feature. A “1” will bypass the low pressure switch for one
minute, a “2” for 2 minutes, etc. The programmed value can be from 0 to 3 minutes. This delay is factory set to 0 for water cooled, glycol cooled, and GLYCOOL units. Typically, only air cooled units need
a “Winter Start” delay time.
Restart—This feature allows for the unit to restart automatically after a loss of power. The programmed value is in 0.1 minute (6 seconds) intervals. A programmed value of zero (0) would require
the user to manually press the ON/OFF key to start the unit, i.e. no auto restart. The purpose of this
feature is to prevent several units from starting at the same time after a loss of power. The message
“Restart Delay -- Please Wait” will be displayed when the system is in the auto restart mode. Liebert
suggests programming multiple unit installations with different auto restart times.
IR Fill Rate (infrared humidifiers only)—An autoflush system automatically controls a water
makeup valve to maintain the proper level in the infrared humidifier water pan during humidifier
operation. If humidification is needed and 15 hours have elapsed since the last time the humidifier
was on, the humidifier is held off until the valve completes an initial fill of the humidifier pan. This
pre-fill is about 30 seconds. The valve continues to fill and flush the pan for about 4 minutes.
During humidifier operation, with the flush rate set at the default of 150%, the valve is opened periodically to add water to the pan (about 40 seconds for every 9-1/2 minutes of humidifier operation).
This adds enough water to the pan to cause about a third of the total water used to be flushed out the
overflow standpipe located in the humidifier pan. This flushing action helps remove solids from the
pan. The flush rate is adjustable from 110% to 500%. If the water quality is poor, it may be desirable
to increase the water flushing action above the normal 150% rate. Also, if the supply water pressure
is low, the flush rate adjustment can be increased so that sufficient water level is maintained during
humidification.
Chilled Water/Hot Water/Econ-O-Coil Flush—This feature will flush the respective coil for
3 minutes after the programmed number of hours of non-use. For example, if the flush time is programmed with 24 hours on a hot water reheat type system and heating is not required for a 24 hour
period, the hot water valve will be open for 3 minutes to allow the coil to be flushed. The programmed
value can be from 0 (no flush) to 99 (99 hours of non-use).
C/F Degrees—The control can be selected to show readings and setpoints in either degrees Fahrenheit (F) or Celsius (C).

7

Operation with Advanced Microprocessor Controls

Table 2 lists the setup functions, their factory default values and the allowable programming ranges.
Table 2

Setup functions, default values and ranges
Function

Default

Range

Cold Start Time Delay*
Restart Time Delay

3
0.1

0 to 3 min (0 = no delay)
0 to 9.9 min (0 = manual restart)

Infrared Fill Rate
Chilled/Hot Water Coil Flush
C/F Degrees

150
24
F

110 to 500%
0 to 99 hrs (also Econ-O-Coil)
C or F

*Factory set to 0 for water cooled, glycol, and GLYCOOL units.

Select Options
The following table lists options which should match the options installed with your unit and should
not need to be changed during normal operation.
Table 3

Unit options

Option

Selection

1

Yes or No

Heating

Humidifier

Yes or No

Dehumidifier

Yes or No

Hot Gas Reheat2

Yes or No

Heat Stages3

2

1Heating

cannot be disabled on units with SCR reheats.
2Hot gas reheat not available on units with SCR reheats.
3
Heat stages not selectable on units with SCR reheats.

Calibrate Sensors
The temperature and humidity sensors can be calibrated by selecting this menu item. “SENSOR”
shows the actual sensor reading or raw reading. “CALIBRATED” shows the sensor reading after the
calibration offset has been added. The temperature sensor can be calibrated ±5 degrees Fahrenheit
and the humidity sensor can be calibrated ±10%RH. When calibrating the humidity sensor, the value
shown will always be % RH, even though absolute humidity control may be selected. If absolute
humidity control is selected, the Normal Status Display will display the adjusted reading and may not
agree with the relative humidity reading displayed while in calibration.

Show DIP Switches
The DIP switch settings can be reviewed from the display panel. Changing the DIP switches requires
opening the upper panel for access to the DIP switches on the microprocessor control board.
NOTE
Power MUST be cycled OFF, then ON from the unit disconnect switch for the control
system to update the DIP switch settings (with the exception of switch 8).
Table 4

DIP switch settings

Switch #

a

Off

On

1

No Part Coil

Part Coil/Chilled Water

2

Electric/Hot Gas Reheat

Hot Water Reheat

3

All

Not Used

4

No GLYCOOL

GLYCOOL

5

No Dual Cooling

Dual Cooling

6

Not Used

Not Used

7a

Tight Control

Standard Control

SCR reheats only (with special software); otherwise, not used.

The selections shown in Table 4 should match options installed on your unit and should not need to
change during normal operation. Switches 1 through 7 are self explanatory. DIP switch 8, not shown in the
table, enables the password feature when set to ON and disables the password feature when set to OFF.
8

Operation with Advanced Microprocessor Controls

Select Control Type
• Intelligent (Chilled Water only)
• Proportional (all unit types)
• Tunable PID (Chilled Water or SCR Reheats only)
The type of system control method used by the microprocessor can be selected from the front panel.
The default setting is Intelligent, which approximates the actions that a human operator would take
to maintain precise, stable control. The control logic uses Artificial Intelligence techniques including
“fuzzy logic” and “expert systems” methods to maintain precise, stable control and increase reliability
by reducing component cycles. Proportional is a standard control method that uses one gain factor
(temperature sensitivity adjustment). Tunable PID (Proportional, Integral, and Derivative) uses
three gain factors selected by the operator. PID allows precision tuning, but requires an experienced
operator and seasonal adjustments. Note that if PID is selected, it is used for temperature control
while humidity will continue to use Proportional control. Refer to 4.0 - System Performance with
Advanced Microprocessor Controls for more detail on types of controls.

Setup Alarms
Selecting SETUP ALARMS will step to the following menu:
•
•
•
•

SET TIME DELAYS
ENABLE ALARMS
ENABLE COMMON ALARM
SET CUSTOM ALARMS

Each individual alarm can be programmed with a time delay from 0 to 255 seconds. Each individual
alarm can be ENABLED or DISABLED and each individual alarm can be programmed to energize or
not to energize the Common Alarm Relay.
Set Time Delays—By programming a time delay for an alarm, the system will delay the specified
amount of time before recognizing the alarm. The alarm condition must be present for the amount of
time programmed for that alarm before it will be annunciated. If the alarm condition goes away
before the time delay has timed out, the alarm will not be recognized and the time delay timer will be
reset. For software alarms such as Loss of Power, Short Cycle, and Low Suction Pressure, a time
delay will only delay the annunciation of that alarm. The condition of the alarm is not applicable
because the condition has already occurred. For these alarms the time delay should be left at the factory default of 0. Table 5, below, shows the default time delays for each alarm.
Table 5

Alarm default time delays
Alarm

Default Time
Delay (seconds)

Humidifier Problem

2

High Head Pressure

2

Change Filter

2

Loss of Air flow

3

Custom Alarm #1

0

Custom Alarm #2

0

Custom Alarm #3

0

Custom Alarm #4

6

High Temperature

30

Low Temperature

30

High Humidity

30

Low Humidity

30

Low Suction Pressure

0

Short Cycle

0

Compressor Overload

2

Main Fan Overload

5

Loss of Power

0

9

Operation with Advanced Microprocessor Controls

Enable Alarms—Each individual alarm can be selected to be ENABLED (annunciated audibly, visually, and communicated to a Site Products System) or DISABLED (ignored).
Enable Common Alarm—Each individual alarm can be selected to energize or to not energize the
common alarm relay. If the energize common alarm function is set to YES, the relay is energized
immediately as the alarm is annunciated and de-energized when the alarm condition goes away (only
after the alarm has been recognized). If the function is set to NO, the alarm has no effect on the common alarm relay regardless of whether the alarm is ENABLED or DISABLED.
Set Custom Alarms—The custom alarm messages can be from a list of standard alarm messages or
you can write your own message.
NOTE
A maximum of two of the alarm messages can be your own message.
They can be in any location(s) 1 through 4. The text for custom alarms can be changed at any time by
selecting “SET CUSTOM ALARMS.” To change the text for a custom alarm, select “SELECT
ALARM.” Then, select the alarm you would like to change, 1 through 4. Using the UP/DOWN arrows
will step through the list of five standard alarm messages (see list below) and the two custom alarms.
NOTE
The two custom alarm messages will be shown with what was previously programmed in them
and can be changed.
Press ENTER to make your selection. To modify the two custom alarm messages, go back one screen
and select “CHANGE CUSTOM TXT 1” (or 2). Text can be up to 20 characters in length and can be
any of the following characters (or a blank space):
ABCDEFGHIJKLMNOPQRSTUVWXYZ#%*-0123456789.
Standard Custom Alarm Messages
•
•
•
•
•

WATER UNDER FLOOR
SMOKE DETECTED
STANDBY GC PUMP ON
LOSS OF WATER FLOW
STANDBY UNIT ON

For more information concerning alarms, see 5.0 - Alarm Descriptions.

Humidity (HUM) Control Method
The user may select between relative (direct) and absolute (predictive) humidity control. If relative is
selected, the RH control is taken directly from the RH sensor. If absolute is selected, the RH control is
automatically adjusted as the return air temperature deviates from the desired temperature setpoint.
This results in a predictive humidity control. The display will indicate % RH for both methods of control, but the adjusted humidity reading will be displayed if absolute is selected. With absolute humidity control, the humidity control is automatically adjusted approximately 2% RH for each degree
difference between the return air temperature and the temperature setpoint.
With relative humidity control, unnecessary dehumidification can result when overcooling occurs during a dehumidification cycle. This is because a higher than normal RH reading is caused by overcooling the room (about 2% RH for each degree of overcooling). This extends the dehumidification cycle.
Later, when the dehumidification ends and the temperature rises to the setpoint, the RH reading
falls. The final RH reading will then be lower than actually desired. If the overcooling was significant
enough, the RH could be low enough to activate the humidifier.
If absolute humidity control is selected, over-dehumidification is avoided. When overcooling occurs,
causing an increase in the RH reading, the humidity control program “predicts” what the RH will be
when the dehumidification cycle ends and temperature returns to the setpoint. This allows the dehumidification cycle to end at the proper time. The predictive humidity control can reduce energy consumption by minimizing compressor and reheat operation, and eliminating unnecessary humidifier
operation.
10

Operation with Advanced Microprocessor Controls

Analog Setup
For installation of analog sensors, see 4.5.1 - Connecting the Analog Sensors.
After selecting a compatible sensor and properly wiring it to the terminals, set up the control to monitor the sensor as follows:
Slope—The slope is a multiplier used to scale the input signal. The slope can be positive (rising) or
negative (falling) and can range from 0 (resulting in a horizontal line) to ±999. The slope for a 0-5 volt
input is per 1 volt input, for 0-10 volt input is per 2 volt input, and for 4-20 mA is per 4 mA input. For
example, assuming an intercept of 0, for a 0-10 volt sensor input with a slope of 50, an input of 1 volt
would be displayed as 25: 1x(50/2); 2 volts would be 50: 2x(50/2); 3 volts would be 75: 3x(50/2); etc.
Intercept—The intercept is an offset from point 0 corresponding to 0 volts or 0 mA input. The intercept can be positive or negative and can be a point from 0 to ±999.
Adding an intercept of 100 to the slope example above, 1 volt would be 125: 100 + (1x[50/2]); 2 volts
would be 150: 100 + (2x[50/2]); 3 volts would be 175: 100 + (3x[50/2]); etc.
NOTE
For a 4-20 mA input sensor, if the desired reading at 4 mA input is 0, then an intercept of
-1 x slope would be required. For example, assuming a slope of 50, the formula would be
([-1 x 50] + 4 x [50/4]) = 0. The intercept is -50.
Text—You may enter a custom label for each analog input. The text label can be 20 characters in
length including any of the following:
ABCDEFGHIJKLMNOPQRSTUVWXYZ#%*-0123456789, or space.

Set Status Display
The Status Display can be set to display the return air temperature and humidity SENSOR READINGS or the temperature and humidity control SETPOINTS through this selection. When SETPOINTS is selected, the status display indicates so by displaying “SETPTS.” If SENSOR READINGS
is selected, the Status Display will show the return air sensor readings.

Calibrate Actuator
For systems that use a valve actuator for chilled water or GLYCOOL cooling, the actuator timing may
be calibrated or adjusted. This is the time it takes for the valve to travel from full closed to full open.
It is programmable from 0 to 255 seconds. The factory default time is 165 seconds and should not be
changed unless the actual valve travel time is not correct. The full valve travel time is used by the
control to determine the appropriate valve position. For example, if the valve travel time is 165 seconds and 50% cooling is being called for, the valve will open for 83 seconds to acheive 50% open. To
change the valve travel time, first enter the “CALIBRATE ACTUATOR” screen. The display will show
the present period used by the control for valve actuator full travel. Press ENTER and adjust the time
using the UP/DOWN arrows. When the correct time is displayed, press ENTER to store the new time
to memory.

11

Operation with Advanced Microprocessor Controls

2.5.3

Run Diagnostics
By selecting Run Diagnostics, maintenance personnel can check system inputs, outputs, and complete
a test of the microcontroller circuit board, all from the front panel. Review of the system inputs and
the microcontroller test can be done without interrupting normal operation. To test the system outputs, the normal system control is temporarily suspended. DO NOT leave the unit in the diagnostics
mode any longer than is necessary for troubleshooting. The control system will return to normal operation in 5 minutes, automatically, if no key is pressed.

Show Inputs
With the unit on and the fan running, the input state for the following devices may be displayed:
•
•
•
•
•
•
•
•
•

Air sail switch: normally off unless Loss of Air Alarm is active
Custom alarm #1: normally off unless this alarm is active
Custom alarm #2: normally off unless this alarm is active
Custom alarm #3: normally off unless this alarm is active
Custom alarm #4: normally off unless this alarm is active
Humidifier problem: normally on unless this alarm is active
Filter clog: normally off unless Change Filters Alarm is active
Main fan overload: normally on unless Main Fan Overload Alarm is active
Shutdown device: normally on unless unit is off through the Fire Stat or Remote Shutdown
Device
• Low press switch: normally on if compressor circuit is in operation
• Comp overload: normally on unless Compressor Overload Alarm is active
• High head comp: normally off unless High Head Pressure alarm Compressor is active

Test Outputs
When this feature is selected, the unit is effectively turned off. When stepping from one load to the
next, the previous load, if on, is turned off automatically. The loads can also be toggled ON/OFF by
selecting “ENTER.” Once turned on, the output will remain on for 5 minutes unless toggled off or the
Test Outputs function is exited by selecting “MENU/ESC.” (The compressor is limited to 15 seconds
on to prevent damage.) The outputs are as follows:
•
•
•
•
•
•
•
•
•
•
•
•
•

!

Main fan: main fan contactor
Comp: compressor contactor
LLSV: liquid line solenoid valve
HGBP/CUV: hot gas bypass or compressor unloader valve (on certain units)
Part coil: part coil solenoid valve
CWV/CGV: chilled water or GLYCOOL valve
R5 Relay: Relay 5 (heat rejection)
Reheat 1: Reheat 1 contactor (also energizes fan for safety) or SCR Reheats
Reheat 2: Reheat 2 contactor (also energizes fan for safety)
HWR: hot water solenoid valve
Humidifier: humidifier contactor (also energizes humidifier makeup valve and fan for safety)
HMV: humidifier makeup valve
Comm alarm: common alarm relay

CAUTION

Do not test a compressor output for more than a few seconds. Compressor damage could
result!

Test Control Board
By selecting this function, the microcontroller will perform a self test lasting approximately 10 seconds. At the end of the test, the ROM checksum, ROM part number and version number will be displayed.

12

Operation with Advanced Microprocessor Controls

2.5.4

Change Passwords
The display prompts you to enter a three digit password when making changes. The system includes
two (2) passwords, one for setpoints and one for setup. The system allows the passwords to be changed
by first entering the present password, factory set as “123” for setpoints and “321” for setup. The password function provides system security, so only personnel authorized to make changes should know
the passwords. If unauthorized changes are being made, the passwords may be compromised and new
ones should be selected. The password function can be disabled by setting DIP switch 8 to OFF.

2.6

Date and Time
The current date and time is available through the display. This feature allows the date and time to
be read or changed and is accessed by selecting “DATE AND TIME” from the Main Menu.
The “DATE AND TIME” is used only by the control for recording the Alarm History.
NOTE
The clock uses the 24 hour system (For example: 17:00 would be 5:00 PM). The date and time
are backed up by battery.

2.7

Status Display
The Status Display selected from the Main Menu is the same Status Display that is normally on the
screen. While the Main Menu is displayed, you can press the MENU/ESC key to return to the Status
Display.
NOTE
The system automatically returns to the Status Display in five minutes if no
control keys are pressed.

2.8

Control Circuit Board
The control circuit board is located inside the unit behind the LCD display and control key panel.
Open the front panel for access to the board.
The control board includes an adjustment for LCD display contrast, nonvolatile memory, DIP
switches (which should not require customer changes), control output LEDs and jumpers for board
configuration. The jumpers should be placed as follows:
P5—removed
P12—removed
P19—installed on Pins 1 and 2
P47—installed on Pins 1 and 2
P48—installed on Pins 1 and 2
P50—all jumpers installed for 4-20 mA analog inputs. See 4.5.1 - Connecting the Analog Sensors for other configurations
P51—removed

2.8.1

LCD Display Contrast
The level of contrast due to viewing angle of the LCD display can be adjusted using a small thumb
wheel at the upper left of the control board just under the cable going to the display. The control is
labeled R6.
NOTE
The LED backlighting on the text (4 x 20) display is always lit.

13

Operation with Advanced Microprocessor Controls

2.8.2

Non-Volatile Memory
All critical information is stored in nonvolatile memory. Setpoints, setup parameters, and component
run hours are kept inside the microcontroller in EEPROM. Information retained for the alarm history
is kept in non-volatile RAM.

2.8.3

DIP Switches
Equipment options are selected and enabled using DIP switches 1 through 7. These are located at the
upper left of the control board and are labeled SW1. Switch 1 is at the top. These switches are factory
set and should not require any user changes. The setting and function of the switches can be read
from the LCD display (see Show DIP Switches on page 8 or the accompanying Table 4).

2.8.4

Control Outputs
Active control outputs are indicated with LEDs on the lower section of the control board. Each LED is
lit if the control output is active (on). The LEDs assist in troubleshooting the system. Refer to the following table.
Table 6

Control output LEDs

LED

Control Output

R5

Heat Rejection

LLSV

Liquid Line Solenoid Valve

HGBP

Hot Gas By-Pass or Compressor Unloader Valve

C1

Compressor

RH1

Reheat Stage 1, Hot Gas, Hot Water Reheat Solenoid or SCR Reheats

RH2

Reheat Stage 2

HUM

Humidifier

FAN

Main Fan

HMV

Humidifier Make-Up Valve

LLSV2

Part Coil Solenoid Valve

14

Operation with Advanced Microprocessor with Graphics Control

3.0

OPERATION WITH ADVANCED MICROPROCESSOR WITH GRAPHICS CONTROL
The advanced microprocessor with graphics (G) control for your Liebert Challenger 3000 unit features
an easy to use, menu driven LCD Graphics Display. The menus, control features, and circuit board
details are described in this section. For more details on the control refer to 4.0 - System Performance with Advanced Microprocessor Controls; for details on the alarms refer to 5.0 - Alarm
Descriptions.

3.1

Basics
Control keys include ON/OFF, Menu/ESCape, ENTER, Increase (UP) arrow, and Decrease (DOWN)
arrow. Refer to Figure 3. These keys are used to move through the menus as prompted on the LCD
display (refer to Figure 4).
To turn the unit ON, press the ON/OFF key after power is applied. To turn the unit OFF, press the
ON/OFF key before power is disconnected.
Active alarms are indicated on the LCD screen by a ringing bell. Alarms are also annunciated by an
audible beeper. To silence an alarm, press the ENTER key as prompted on the display. The unit
stores the 60 most recent alarms for review.
Setpoints, DIP switch settings, and other selections were made on your unit before testing at the factory and are kept in nonvolatile memory. Setpoints were chosen based on typical operating experience. Other selections were made based on options included with your unit. Make adjustments to the
factory default selections ONLY if they do not meet your specifications. When entering setpoints, time
delays, etc., the allowable ranges are displayed and may require a password, if enabled.

Figure 3

Advanced microprocessor with graphics (G) control panel

15

Operation with Advanced Microprocessor with Graphics Control

Figure 4

Advanced microprocessor with graphics control menu
Use UP/DOWN to move
the cursor. Hit ENTER
to select the menu item.

72°F Unit On
50%RH
Dehumidifying
Cooling

Normal Display

Any key
except
ON/OFF

ESC key moves backward
through menus toward the
Main Menu

ESC key

***Main Menu***

View/Set
Alarms

Operating
Status

View/Set
Control
Setpoints

Setup
System

Operating Status

View/Set Setpoints

Compressor Cooling %
Heating %
GLYCOOL %**
Chilled Water Valve %**
Dehumidification %
Humidification %

Temperature Setpoint
Sensitivity Setpoint
Humidity Setpoint
Sensitivity
High Temperature Alarm
Low Temperature Alarm
High Humidity Alarm
Low Humidity Alarm

Run
Diagnostics

View/Set Alarms
Active Alarms
Alarm History
Setup Alarms
High Temperature
Low Temperature
High Humidity
Low Suction Pressure
Short Cycle
Compressor Overload
Main Fan Overload
Loss of Power
Humidifier Problem
High Head Pressure
Change Filters
Loss of Air Flow
Custom Alarm 1
Custom Alarm 2
Custom Alarm 3
Custom Alarm 4
Setup Custom Alarms
Setup Custom Alarm Text
Change Custom Text 1
Change Custom Text 2
Change Custom Text 3
Change Custom Text 4
View Water
Detect Floor Plan
Setup Water
Detect Floor Plan
Use / to locate file
Use ENTER to define file

*
**
***

Setup System
Setup Operation
Cold Start Delay
Auto Restart Delay
IR Flush Overfill
CW / HW Coil Flush**
Display in Degrees (F / C)
Min Chilled Water Temp**
Select Options
Reheat
Humidify
Dehumidify
Hot Gas Reheat
Stages of Reheat
Calibrate Sensors
Temperature Sensor
Humidity Sensor
Calibrated Reading
Calibrate Valve Actuator
Select Control Algorithm*
Proportional
Intelligent
Tunable PID
Proportional Gain
Derivative Gain
Integral Gain
Select Humidity
Sensing Mode
Relative
Absolute
Set Status Display
Sensor Reading
Setpoints
Change Passwords
Setpoint Password
Setup Password
Change Passwords

Date and
Time

Plot Graphs

Analog/
Digital Inputs

Date and Time

View Run
Hours Log

View Run Hours Log

Set Clock
View 24 Hour Run
Time History
Chilled Water**
GLYCOOL**
Compressor
Reheat 1,2
Humidifier
Main Fan
View Total Run Hours
Compressor
GLYCOOL**
Chilled Water Valve**
Main Fan
Humidifier
Reheat 1,2
Heat Rejection

Run Diagnostics
Show Inputs
Air Sail Switch
Custom Alarm 1
Custom Alarm 2
Custom Alarm 3
Custom Alarm 4
Humidifier Problem
Filter Clog Switch
Main Fan Overload
Shutdown Device
Low Pressure
Switch
Compressor
Overload
High Head Pressure
Test Outputs
Main Fan
Compressor
Liquid Line SV
HGBP/CUV
CW/CGV
Dehumidification***
R5 Relay
Reheat 1
Reheat 2
RH3 Dehum
Damper
Humidifier
HMV
Common Alarm
Test Control Board
Microcontroller
Show DIP Switches
Dipswitch 1
Dipswitch 2
Dipswitch 3
Dipswitch 4
Dipswitch 5
Dipswitch 6
Dipswitch 7

Select Control Algorithm available on Chilled Water only
optional
Himod units only

16

Analog/Digital Inputs
Read Analog Inputs
Analog Input 1
Analog Input 2
Analog Input 3
Analog Input 4
Set Analog Inputs
Analog Input 1 (2,3,4)
Slope
Units
Text
Intercept
Read Digital Inputs
Setup Digital nputs
(How-to Text)
Plot Graphs
Temperature Plot
Humidity Plot
Analog Sensor #1 Plot
Analog Sensor #2 Plot
Analog Sensor #3 Plot
Analog Sensor #4 Plot
Modify Plot Scales
Modify Temp Scales
Modify Humidity Scales
Modify Analog Sensor
# 1 Scale
# 2 Scale
# 3 Scale
# 4 Scale

Operation with Advanced Microprocessor with Graphics Control

3.2

Status Display
The normal status screen is divided into two sections, a right half and a left half. The left half displays
the return air temperature and humidity readings in large characters.
NOTE
The display can also be set to display the temperature and humidity setpoints.
See 3.7.7 - Set Status Display.
The right half of the screen is divided into four quadrants (top to bottom). In the four quadrants, six
different graphic symbols may be displayed depending on the unit status. At the top there will be a
moving hammer striking a bell that appears when an alarm is present. The word “Alarm” also
appears next to the hammer and bell. The second quadrant down displays a rotating fan as long as
the unit is turned on and the fan is running. The words “Unit on” appear next to the fan symbol. The
third quadrant may display one of two symbols relating to heating or cooling. If the control is calling
for cooling, a growing snowflake is shown next to the word “Cooling.” If the control is calling for heating, three moving heat rays are displayed next to the word “Heating.” In the bottom quadrant, there
may be one of two symbols relating to humidification and dehumidification. If the control is calling for
humidification, a growing water drop is shown next to the word “Humidification.” If the control is calling for dehumidification, a shrinking water drop is shown next to the word “Dehumidification.”

3.3

Main Menu 
Press the MENU/ESC key to display the Main Menu. The Menu selections include:
•
•
•
•
•
•
•
•
•

VIEW/SET ALARMS
OPERATING STATUS
VIEW/SET CONTROL SETPOINTS
SYSTEM SETUP
RUN DIAGNOSTICS
DATE AND TIME
PLOT GRAPHS
ANALOG/DIGITAL INPUTS
VIEW RUN HOURS LOG

Pressing the MENU/ESC key while the Main Menu is displayed will return the screen to the Status
Display.

3.4

View/Set Alarms
Selecting VIEW/SET ALARMS will step to the following menu:
•
•
•
•
•
•

3.4.1

ACTIVE ALARMS
ALARM HISTORY LOG
SETUP ALARMS
SETUP CUSTOM ALARMS
VIEW WATER DETECT FLOOR PLAN
SETUP WATER DETECT FLOOR PLAN

Active Alarms
This screen displays any active alarm. The alarms are numbered, #1 being the most recent. The type
of alarm (Urgent or Warning) is also displayed. If there are no active alarms, then “NO ALARMS
PRESENT” will be displayed.

3.4.2

Alarm History Log
A history of the 60 most recent alarms is kept in nonvolatile memory complete with the type of alarm,
the alarm name, and the date and time it occurred. The first alarm in the history is the most recent
and the last (up to 60) is the oldest. If the Alarm History is full (60 alarms) and a new alarm occurs,
the oldest is lost and the newest is saved in alarm history location 1. The rest are moved down the list
by 1. Alarm history on new units may show the results of factory testing.
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Operation with Advanced Microprocessor with Graphics Control

3.4.3

Setup Alarms
The list of alarms may be reviewed using the UP/DOWN keys. Any alarm may be selected to have it's
parameters modified by pressing the ENTER key. All alarms have a time delay and alarm type
parameter. The high/low temperature and humidity alarms also have a programmable Trip Point.
The Trip Point is the point at which the alarm is activated. By programming a time delay for an
alarm, the system will delay the specified amount of time before recognizing the alarm. The alarm
condition must be present for the amount of time programmed for that alarm before it will be annunciated. If the alarm condition goes away before the time delay has timed out, the alarm will not be recognized. For software alarms such as Loss of Power, Short Cycle, and Low Suction Pressure, a time
delay will only delay the annunciation of that alarm. The condition of the alarm is not applicable
because the condition has already occurred. For these alarms, the time delay should be left at the factory default of 0.
The following table shows the default time delays for each alarm.
Table 7

Alarm default time delays
Alarm

Default Time
Delay (seconds)

Humidifier Problem

2

High Head Pressure

2

Change Filter

2

Loss of Air flow

3

Custom Alarm #1

0

Custom Alarm #2

0

Custom Alarm #3

0

Custom Alarm #4

6

High Temperature

30

Low Temperature

30

High Humidity

30

Low Humidity

30

Low Suction Pressure

0

Short Cycle

0

Compressor Overload

2

Main Fan Overload

5

Loss of Power

0

Each individual alarm can be selected as either DISABLED, WARNING, or URGENT. The four custom alarms may also be selected to be a Status Only input. If the alarm is DISABLED, it is ignored. If
the alarm is WARNING or URGENT, it will be annunciated audibly, visually, and communicated to a
Site Products System if appropriate. When the alarm is selected to be a WARNING, the alarm will
NOT activate the common alarm relay. When the alarm is selected to be URGENT, the alarm is first
annunciated as a WARNING, and then annunciated again, after the programmed time delay. When
the alarm becomes URGENT, the control will activate the common alarm relay. The common alarm
relay is de-energized after the alarm has been recognized and when the alarm no longer exists. When
the alarm type has been selected to be URGENT, the allowable range for the time delay from warning
to urgent is 0 minutes to 999 hours. When any of the four custom alarm inputs have been selected as
Status Only, they become digital inputs for monitoring only and are no longer treated as alarms.

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3.4.4

Setup Custom Alarms
Selecting SETUP CUSTOM ALARMS will step to the following menu:
•
•
•
•
•

SETUP CUSTOM ALARM TEXT
CHANGE CUSTOM TEXT 1
CHANGE CUSTOM TEXT 2
CHANGE CUSTOM TEXT 3
CHANGE CUSTOM TEXT 4

The custom alarm messages can be selected from a list of standard messages or you can write your
own messages. The message selected for any custom alarm can be changed at any time by selecting
SETUP CUSTOM ALARM TEXT. A list of five standard messages (see list below) and four custom
messages are available to choose from. To modify the custom messages press CHANGE CUSTOM
TEXT 1 (2, 3 or 4). Each message can be up to 20 characters in length and can be any of the following
characters (or a blank space):
ABCDEFGHIJKLMNOPQRSTUVWXYZ#%*-0123456789.
Standard Custom Alarm Messages
•
•
•
•
•

WATER UNDER FLOOR
SMOKE DETECTED
STANDBY GC PUMP ON
LOSS OF WATER FLOW
STANDBY UNIT ON

For more information concerning alarms, see 5.0 - Alarm Descriptions.

3.4.5

View Water Detect Floor Plan (for Optional LTM1000/LT750)
When water is detected the alarm will sound and the WATER UNDER FLOOR alarm message will be
displayed. To see where the water is in the room, select VIEW/SET ALARMS from the main menu,
then VIEW WATER DETECT FLOOR PLAN. A tile will be highlighted and blinking to indicate the
position of the detected water.

3.4.6

Setup Water Detect Floor Plan
The selected (i.e., cursor) floor tile will be highlighted and blinking. The UP and DOWN arrow keys
are used to position the cursor tile. The UP key will move the cursor tile up and then it wraps around
to the bottom of the next column to the right. The DOWN arrow key moves the cursor down, then to
the top of the next column to the left. The cursor will also wrap around from the right top tile to the
left bottom tile and back.
There are three different types of tiles to be defined: the environmental unit, the LT750 and sensor
cable tiles. To set up the cable layout, first move the cursor to the location of the environmental unit
and press the ENTER key. A rectangular box will be drawn at that location. Then move the cursor to
the location of the LT750 and press the ENTER key. A solid circle will be drawn on the display. No
tile can have two definitions, so if the LT750 is physically directly under the unit it must be defined at
least one tile away.
The sensor cable should not be defined one tile at a time. The only sensor cable tiles that need to be
defined are the tiles where the cable is going to change direction, and the last tile. The display will
automatically define any tiles between two consecutively defined sensor tiles to be sensor tiles.
The ENTER key is also used to undo tile definitions. If a tile is defined in the wrong place, position
the cursor on that tile and press the ENTER key. It will undefine the tile under the cursor and move
the cursor back to the last defined tile. The entire layout can be erased by successively pressing the
ENTER key. When the last tile is defined, press the ESCape key to leave the setup screen.
For more information and detailed installation instructions, see 4.5.2 - Water Detection Display.

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3.5

Operating Status
The Operating Status is intended to provide the user with displayed information about what the control is calling for the system to do.
NOTE
There may be some time lapse before a specific component matches the displayed number.
For example: The display indicates the chilled water valve is 68% open. On a new call for cooling, it
takes several seconds for the valve to travel from full closed to 68% open. So when the display reads
68%, it may take a few seconds for the valve to actually open 68%. Also, if the display indicates a compressor is operating but the compressor has not turned on yet, it may be off because of the short cycle
control (see 4.4.1 - Short Cycle Control).

3.6

View/Set Control Setpoints
Control setpoints can be reviewed and/or changed through the display. Refer to the following table to
see the list of default setpoints and their allowable ranges.
Table 8

Default setpoints and ranges
Setpoint

3.7

Default

Range

Temperature Setpoint

72°F

40 to 90°F (5 to 32°C)

Temperature Sensitivity

2.0°F

1 to 9.9°F (0.6 to 5.6°C)

Humidity Setpoint

50%

20 to 80% RH

Humidity Sensitivity

5%

1 to 30% RH

High Temperature Alarm

80°F

35 to 95°F (2 to 35°C)

Low Temperature Alarm

65°F

35 to 95°F (2 to 35°C)

High Humidity Alarm

60%

15 to 85% RH

Low Humidity Alarm

40%

15 to 85% RH

System Setup
Selecting SYSTEM SETUP will step to the following menu:
•
•
•
•
•
•
•
•

3.7.1

SETUP OPERATION
SELECT OPTIONS
CALIBRATE SENSORS
CALIBRATE VALVE ACTUATOR
SELECT CONTROL ALGORITHM (chilled water or SCR Reheats only)
SELECT HUMIDITY SENSING MODE
SET STATUS DISPLAY
CHANGE PASSWORDS

Setup Operation
The SETUP OPERATION menu permits the review and/or adjustment of the unit configuration. This
may include:

Cold Start Delay
This feature, also referred to as Positive Start or Winter Start Kit, allows for the low pressure switch
to be ignored for the programmed time during a cold start of the compressor. Entering a “0” for this
time will bypass this feature. A “1” will bypass the low pressure switch for one minute, a “2” for two
minutes, etc. The programmed value can be from 0 to 3 minutes. This delay is factory set to 0 for
water cooled, glycol cooled, and GLYCOOL units. Typically, only air cooled units need a “Winter
Start” time.

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Operation with Advanced Microprocessor with Graphics Control

Auto Restart Delay
This feature allows for the unit to restart automatically after a loss of power. The programmed value
is .1 minute (6 seconds) intervals. A programmed value of zero (0) would require the user to manually
press the ON/OFF switch to start the unit, i.e. no auto restart. The purpose of this feature is to prevent several units from starting at the same time after a loss of power. The message “Restart Delay -Please Wait” will be displayed when the system is in the auto restart mode. Liebert suggests programming multiple unit installations with different auto restart times.

IR Flush Overfill (infrared humidifiers only)
An autoflush system automatically controls a water makeup valve to maintain proper level in the
infrared humidifier water pan during humidifier operation. If humidification is needed and 30 hours
have elapsed since the last time the humidifier was on, then the humidifier is held off until the valve
completes an initial fill of the humidifier pan. This pre-fill is about 15 seconds. The valve continues to
fill and flush the pan for about 4 minutes.
During humidifier operation, with the flush rate set at the default of 150%, the valve is opened periodically to add water to the pan (about 40 seconds for every 9-1/2 minutes of humidifier operation).
This adds enough water to the pan to cause about a third of the total water used to be flushed out the
overflow standpipe located in the humidifier pan. This flushing action helps remove solids from the
pan. The flush rate is adjustable from 110% to 500%. If the water quality is poor, it may be desirable
to increase the water flushing action above the normal 150% rate. Also, if the supply water pressure
is low, the flush rate adjustment can be increased so that sufficient water level is maintained during
humidification.

Chilled Water/Hot Water/Econ-O-Coil Flush
This feature will flush the respective coil for 3 minutes after the programmed number of hours of
non-use. For example, if the flush time is programmed with 24 hours on a hot water reheat type system, and heating is not required for a 24 hour period, the hot water valve will be opened for 3 minutes
to allow the coil to be flushed. The programmed value can be from 0 (no flush) to 99 (99 hours of
non-use).

Display in Degrees
The control can be set to display readings and setpoints in either degrees Fahrenheit (F) or
Celsius (C).

Default Settings and Ranges
The following table lists the setup functions, their factory default values, and the allowable ranges for
which they can be programmed.
Table 9

Setup functions, default values and ranges
Function

Cold Start Time Delay*

Default
3

Range
0 to 3 min (0 = no delay)

Restart Time Delay

0.1

0 to 9.9 min (0 = manual restart)

Infrared Fill Rate

150

110 to 500%

Chilled/Hot Water Coil Flush

24

0 to 99 hrs (also Econ-O-Coil)

C/F Degrees

F

C or F

*Factory set to 0 for water cooled, glycol, and GLYCOOL units.

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3.7.2

Select Options
The following table is a list of options which should match the options installed with your unit and
should not need to change during normal operation.
Table 10

Unit options

Option

Selection

1

YES or NO

Humidity

YES or NO

Reheat

Dehumidify

YES or NO

Hot Gas Reheat2

YES or NO

Stages of Reheat3

2

1

Heating cannot be disabled on units with SCR reheats.
gas reheat not available on units with SCR reheats.
3Heat stages not selectable on units with SCR reheats.
2Hot

3.7.3

Calibrate Sensors
The temperature and humidity sensors can be calibrated by selecting this menu item. “SENSOR”
shows the actual sensor reading or raw reading. “CALIBRATED” shows the sensor reading after the
calibration offset has been added. The temperature sensor can be calibrated ±5°F and the humidity
sensor can be calibrated ±10% RH. When calibrating the humidity sensor, the value shown will
always be % RH, even though absolute humidity control may be selected. If absolute humidity control
is selected, the Normal Status Display will display the adjusted reading and may not agree with the
relative humidity reading displayed while in calibration.

3.7.4

Calibrate Valve Actuator
For systems that use a valve actuator for chilled water or GLYCOOL cooling, the actuator timing may
be calibrated or adjusted. This is the time it takes for the valve to travel from full closed to full open.
It is programmable from 0 to 255 seconds. The factory default time is 165 seconds and should not be
changed unless the actual valve travel time is not correct. The full valve travel time is used by the
control to determine the appropriate valve position. For example, if the valve travel time is 165 seconds and 50% cooling is being called for, the valve will open for 83 seconds to achieve 50% open. To
change the valve travel time, first enter the “CALIBRATE ACTUATOR” screen. The display will show
the present period used by the control for valve actuator full travel. Press ENTER and adjust the time
using the UP/DOWN arrows. When the correct time is displayed, press ENTER to store the new time
to memory.

3.7.5

Select Control Algorithm (Chilled Water and SCR Reheats only)
The type of system control method used by the microprocessor can be selected from the front panel.
The default setting is INTELLIGENT, which approximates the actions that a human operator would
take to maintain precise, stable control. The control logic uses Artificial Intelligence techniques
including “fuzzy logic” and “expert systems” methods to maintain precise, stable control and increase
reliability by reducing component cycles. PROPORTIONAL is a standard control method that uses
one gain factor (temperature sensitivity adjustment). TUNABLE PID (Proportional, Integral, and
Derivative) uses three gain factors selected by the operator. PID allows precision tuning, but requires
an experienced operator and seasonal adjustments. Note that if PID is selected, it is used for temperature control while humidity will continue to use proportional control. For chilled water units with
the optional Variable Speed Drive, Intelligent is required for proper operation. Refer to 4.0 - System
Performance with Advanced Microprocessor Controls for more details on types of control.

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3.7.6

Select Humidity Sensing Mode
The user may select between RELATIVE (direct) and ABSOLUTE (predictive) humidity control. If
relative is selected, the RH control is taken directly from the RH sensor. If absolute is selected, the
RH control is automatically adjusted as the return air temperature deviates from the desired temperature setpoint. This results in a predictive humidity control. The display will indicate % RH for both
methods of control, but the adjusted humidity reading will be displayed if absolute is selected. With
absolute humidity control, the humidity control is automatically adjusted approximately 2% RH for
each degree difference between the return air temperature and the temperature setpoint.
With relative humidity control, unnecessary dehumidification can result when overcooling occurs during a dehumidification cycle. This is because a higher than normal RH reading is caused by overcooling the room (about 2% RH for each degree of overcooling). This extends the dehumidification cycle.
Later, when the dehumidification ends and the temperature rises to the setpoint, the RH reading
falls. The final RH reading will then be lower than actually desired. If the overcooling was significant
enough, the RH could be low enough to activate the humidifier.
If absolute humidity control is selected, over-dehumidification is avoided. When overcooling occurs,
causing an increase in the RH reading, the humidity control program “predicts” what the RH will be
when the dehumidification cycle ends and temperature returns to the setpoint. This allows the dehumidification cycle to end at the proper time. The predictive humidity control can reduce energy consumption by minimizing compressor and reheat operation, and eliminating unnecessary humidifier
operation.

3.7.7

Set Status Display
The Status Display can be set to display the return air temperature and humidity SENSOR READINGS or the temperature and humidity control SETPOINTS through this selection. When setpoints
are selected, the status display indicates so by also displaying “SETPOINTS.” If SENSOR READINGS is selected, the Status Display will show the return air sensor readings.

3.7.8

Change Passwords
Selecting CHANGE PASSWORDS will prompt the user to select one of the following:
• SETPOINT PASSWORD
• SETUP PASSWORD
The display prompts you to enter a three digit password when making changes. The system includes
two (2) passwords, one for setpoints and one for system setup. The system allows the passwords to be
changed by first entering the present password, factory set as “123” for setpoints and “321” for setup.
The password function provides system security, so only personnel authorized to make changes
should know the passwords. If unauthorized changes are being made, the passwords may be compromised and new ones should be selected. The password function can be disabled by setting DIP switch
8 to OFF.

3.8

Run Diagnostics
By selecting RUN DIAGNOSTICS, maintenance personnel can check system inputs, outputs, and
complete a test of the microcontroller circuit board, all from the front panel. Review of the system
inputs and the microcontroller test can be done without interrupting normal operation.

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3.8.1

Show Inputs
With the unit on and the fan running, the input state for the following devices may be displayed:
•
•
•
•
•
•
•
•
•

Air Sail Switch: normally off unless Loss of Air Alarm is active
Custom Alarm #1: normally off unless this alarm is active
Custom Alarm #2: normally off unless this alarm is active
Custom Alarm #3: normally off unless this alarm is active
Custom Alarm #4: normally off unless this alarm is active
Humidifier Problem: normally on unless this alarm is active
Filter Clog Switch: normally off unless Change Filters Alarm is active
Main Fan Overload: normally on unless Main Fan Overload Alarm is active
Shutdown Device: normally on unless unit is off through the Fire Stat or Remote Shutdown
Device
• Low Pressure Switch: normally on if compressor circuit 1 is in operation
• Compressor Overload: normally on unless Compressor 1 Overload Alarm is active
• High Head: normally off unless High Head Pressure alarm is active

3.8.2

Test Outputs
When this feature is selected, the unit is effectively turned off. When stepping from one load to the
next the previous load, if on, is turned off automatically. The loads can also be toggled on/off by selecting “ENTER.” Once turned on, the output will remain on for 5 minutes unless toggled off or the test
outputs function is exited by selecting “MENU/ESC” (Compressor is limited to 15 seconds on to prevent damage.) DO NOT leave the unit in the test outputs mode any longer than is necessary for troubleshooting. The outputs are as follows:
•
•
•
•
•
•
•
•
•
•
•
•
•

!

3.8.3

Main Fan: main fan contactor
Compressor: compressor contactor
LLSV: liquid line solenoid valve
HGBP/CUV: hot gas bypass or compressor unloader valve (on certain units)
Part Coil: Part Coil Solenoid Valve
CWV/CGV: chilled water or GLYCOOL valve
R5 Relay: Relay 5 (heat rejection)
Reheat 1: Reheat 1 contactor or SCR Reheats (also energizes fan for safety)
Reheat 2: Reheat 2 contactor (also energizes fan for safety)
HWR: hot water solenoid valve
Humidifier: humidifier contactor (also energizes humidifier makeup valve and fan for safety)
HMV: humidifier makeup valve
Common alarm: common alarm relay

CAUTION

Do not test a compressor output for more than a few seconds.
Compressor damage could result!

Test Control Board
By selecting this function, the microcontroller will perform a self test lasting approximately 10 seconds. At the end of the test, the ROM checksum, ROM part number and version number will be displayed.

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3.8.4

DIP Switches
The DIP switch settings can be reviewed from the display panel. Changing the DIP switches requires
opening the front panel for access to the DIP switches on the microprocessor control board.
NOTE
Power MUST be cycled off, then on, from the unit disconnect switch for the control system
to update the DIP switch settings (except for switch 8).
These selections should match options installed on your unit and should not need to change during
normal operation. Switches 1 through 7 are self explanatory. DIP switch 8, not shown in Table 11,
below, enables the password feature when set to ON and disables the password feature if set to OFF.
Table 11

Setting options

Switch #

a

3.9

Off

On

1

No Part Coil

Part Coil/Chilled Water

2

Electric/Hot Gas Reheat

Hot Water Reheat

3

All

Not Used

4

No GLYCOOL

GLYCOOL

5

No Dual Cooling

Dual Cooling

6

Not Used

Not Used

7a

Tight Control

Standard Control

SCR reheats only (with special software); otherwise, not used.

Date and Time
The current date and time is available through the display. This feature allows the date and time to
be read or changed and is accessed by selecting “DATE AND TIME” from the Main Menu. The “DATE
AND TIME” is used by the control for recording the Alarm History and plotting graphs.
NOTE
The clock uses the 24 hour system (For example: 17:00 would be 5:00 PM). The date and time
are backed up by battery.

3.10

Plot Graphs
Selecting PLOT GRAPHS will step to the following menu:
•
•
•
•
•
•
•

TEMPERATURE PLOT
HUMIDITY PLOT
ANALOG SENSOR #1 PLOT
ANALOG SENSOR #2 PLOT
ANALOG SENSOR #3 PLOT
ANALOG SENSOR #4 PLOT
MODIFY PLOT SCALES

Six different data types are recorded for graphing: temperature, humidity, and four user defined analog inputs. Each data type can be viewed over three different time scales and two different resolutions. The three time scales are 90 minutes, 8 hours, and 24 hours. The two resolutions are minimum
and maximum. With minimum resolution selected, the full scale of the sensor is displayed. In other
words, the largest and smallest possible sensor readings are shown. Maximum resolution shows a
range that covers two-fifths of the full scale sensor range.

3.10.1 Modify Plot Scales
The MODIFY PLOT SCALES menu item adjusts the layout of the graph. This setup screen selects
the time scale and resolution. It also adjusts the center of the graph for a maximum resolution graph.
The time scale and resolution can also be changed while the graph is displayed. The DOWN arrow key
changes the time scale from 90 minutes, to 8 hours, to 24 hours. The UP arrow key toggles the display
between maximum and minimum resolution.
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3.11

Analog/Digital Inputs
Selecting ANALOG/DIGITAL INPUTS steps to the following menu:
•
•
•
•

READ ANALOG INPUTS
SETUP ANALOG INPUTS
READ DIGITAL INPUTS
SETUP DIGITAL INPUTS

3.11.1 Read Analog Inputs
The four (4) analog sensor inputs can be monitored from the display. The inputs are filtered, then displayed along with the text label assigned during setup.

3.11.2 Setup Analog Inputs
For installation of analog sensors, see Analog Setup on page 11.
After selecting a compatible sensor and properly wiring it to the terminals, set the control to monitor
the sensor according to the following instructions.

Slope
The slope is a multiplier used to scale the input signal. The slope can be positive (rising) or negative
(falling) and can range from 0 (resulting in a horizontal line) to ±999. The slope for a 0-5 volt input is
per 1 volt input; for 0-10 volt input, it is per 2 volt input; and for 4-20 mA, it is per 4 mA input. For
example, assuming an intercept of 0, for a 0-10 volt sensor input with a slope of 50, an input of 1 volt
would be displayed as 25: 1x(50/2); 2 volts would be 50: 2x(50/2); 3 volts would be 75: 3x(50/2); etc.

Intercept
The intercept is an offset from point 0 corresponding to 0 volts or 0 mA input. The intercept can be
positive or negative and can be a point from 0 to ±999. Adding an intercept of 100 to the slope example
above, 1 volt would be 125: 100 + (1x[50/2]); 2 volts would be 150: 100 + (2x[50/2]); 3 volts would be
175: 100 + (3x[50/2]); etc.
NOTE
For a 4-20 mA input sensor, if the desired reading at 4 mA input is 0, then an intercept
of -1 x slope would be required. For example, assuming a slope of 50, the formula would
be ([-1 x 50] + 4 x [50/4]) = 0. The intercept is -50.

Text
You may enter a custom label for each analog input. The text label can be 20 characters in length
including any of the following:
ABCDEFGHIJKLMNOPQRSTUVWXYZ#%*-0123456789, or space.

3.11.3 Read Digital Inputs
The four custom alarm inputs can be defined to be digital inputs. Digital inputs are used to sense customer devices for status display purposes only and will not activate the audible alarm.

3.11.4 Setup Digital Inputs
A digital input is enabled by defining one of the four custom alarms to be STATUS ONLY type in the
alarm setup screen. The digital input is given a name by specifying it to be one of the optional alarms
or a custom text alarm. See 3.4.3 - Setup Alarms and 3.4.4 - Setup Custom Alarms.

3.12

View Run Hours Log
Selecting VIEW RUN HOURS LOG will step to the following menu:
• VIEW 24 HOUR RUN TIME HISTORY
• VIEW TOTAL RUN HOURS

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3.12.1 View 24 Hour Run Time History
The history of each load for every hour during the past 24 hours is displayed in the run hour history.
The percentage of each hour that the load was on is displayed from 0 to 100% in increments of 5% or
3 minutes. Loads with a variable output are displayed as a percentage of their capacity for an hour.
For example, a variable load that is 50% on for 1/2 of the hour will be displayed as 25% on for that
hour.

3.12.2 View Total Run Hours
The total operating hours of all major components in the unit can be monitored from the display and
are retained in nonvolatile memory. Run times are available for the following:
•
•
•
•
•
•
•

Compressor
GLYCOOL Coil (or Chilled Water Coil as used on Dual Cool Units)
Fan
Humidifier
Reheat 1 (or Hot Water Reheat or SCR Reheats)
Reheat 2
Heat Rejection

The component run hours for each individual component can be reset by selecting the run hours display screen for the desired component, then pressing ENTER within 5 minutes of applying power to
the control. The user will then be prompted to press ENTER to clear the selected component's run
hours.
NOTE
Run hours for a component should be reset ONLY when the component has been replaced.

3.13

Control Circuit board
The control circuit board is located inside the unit behind the LCD display and control key panel.
Open the front panel for access to the board.
The control board includes an adjustment for LCD contrast, nonvolatile memory, DIP switches (which
should not require customer changes), control output LEDs, and jumpers for board configuration. The
jumpers should be placed as follows:
•
•
•
•
•
•

P5—removed
P12—removed
P19—installed on Pins 1 and 2
P47— installed on Pins 1 and 2
P48—installed on Pins 1 and 2
P50—all jumpers installed for 4-20 mA analog inputs. See 4.5.1 - Connecting the Analog Sensors for other configurations.
• P51—removed

3.13.1 LCD Contrast
The level of contrast due to the viewing angle of the LCD can be adjusted using a small thumb wheel
at the upper left of the control board just under the cable going to the display. The control is labeled
RA1.
NOTE
The LCD backlighting will turn on when any key is pressed and will go off 5 minutes after
the last key is pressed.

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Operation with Advanced Microprocessor with Graphics Control

3.13.2 Nonvolatile Memory
All critical information is stored in nonvolatile memory. Setpoints, setup parameters, and component
run hours are kept inside the microcontroller in EEPROM. Information retained for data logging,
24 hour component run hour graphs, alarm history, and the water detection floor plan is kept in nonvolatile RAM.

3.13.3 DIP Switches
Equipment options are selected and enabled using DIP switches 1 to 7. These are located at the upper
left of the control board and are labeled SW1. Switch 1 is at the top. These switches are factory set
and should not require any user changes. The setting and function of the switches can be read from
the LCD (see 3.8.4 - DIP Switches).

3.13.4 Control Outputs
Active control outputs are indicated with LEDs on the lower section of the control board. Each LED is
lit if the control output is active (on). Use these LEDs to assist in troubleshooting the system.
Table 12

Control output LEDs

LED
R5
LLSV
HGBP
C1

Control Output
Heat Rejection
Liquid Line Solenoid Valve
Hot Gas By-Pass
Compressor

RH1

Reheat Stage 1 or Hot Gas, Hot Water Reheat Solenoid
or SCR Reheats

RH2

Reheat Stage 2

HUM

Humidifier

FAN

Main Fan

HMV

Humidifier Make-Up Valve

LLSV2

Part Coil Solenoid Valve

28

System Performance with Advanced Microprocessor Controls

4.0

SYSTEM PERFORMANCE WITH ADVANCED MICROPROCESSOR CONTROLS
This section provides details on how your Challenger 3000 unit responds to user inputs and room conditions. Refer to this section when you need specific information. This section includes details on control.

4.1

Temperature Control

4.1.1

Cooling/Heating Required, in Percent (%)
The temperature control program for the advanced microprocessor is based on a calculated % requirement for cooling/ heating.

4.1.2

Response to Control Types
Proportional Control
The % requirement is determined by the difference between the return air temperature and the temperature setpoint. As the return air temperature rises above the temperature setpoint, the % cooling
required increases proportionally (from 0 to 100%) over a temperature band equal to the temperature
sensitivity plus 1°F. The % heating requirement is determined the same way as the temperature
decreases below the setpoint. With this type of control the temperature at which the room is controlled increases as the room cooling load increases. At full cooling load the room would be controlled
at a temperature equal to the setpoint plus the sensitivity.
For systems with SCR Reheats, the % requirement is determined only by the difference between the
return air temperature and the temperature setpoint. This permits tighter temperature control. The
SCR Reheats are controlled in a proportional manner inversely as described above for cooling. When
the return air temperature is at the temperature setpoint, the SCR Reheats will be on 100%. As the
temperature increased to the temperature setpoint plus the temperature sensitivity, the SCR Reheats
will be pulsed proportionally from full on to full off (0% to 100%) until the return air temperature
reaches the temperature setpoint plus the temperature sensitivity.

PID Control (Chilled Water or SCR Reheats only)
If PID control is selected, the return air temperature is controlled at or near the temperature setpoint
independent of the room load. The % cooling/heating requirement is calculated by adding together
three individual terms - proportional, integral, and derivative.
The proportional term is figured in a manner similar to the previously described proportional control.
The integral term (sometimes called “reset action”) is figured by measuring how much and for how
long the temperature has been above or below the setpoint. If the temperature is above the setpoint,
the % cooling requirement is slowly but continuously increased until the total is sufficient to bring the
temperature back to the setpoint. The derivative term provides an anticipation control for rapid
changes in temperature. If the temperature is rising, the % cooling is increased temporarily until the
temperature begins to stabilize. The % heating requirement is increased if temperature is falling.
The proportional, integral, and derivative terms are all adjustable through the control selection menu
and should be set or “tuned” to the characteristics of the room being controlled (see 4.3 - Control
Types).

Intelligent Control (Chilled Water only)
If intelligent control is selected, the return air temperature is controlled at or near the temperature
setpoint. The % cooling/heating required is calculated based on a set of logical “rules” that are programmed into the control. These “rules” simulate the actions that an expert human operator would
take if manually controlling the system (see 4.3 - Control Types).

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System Performance with Advanced Microprocessor Controls

4.1.3

Cooling Operation
1-Step Cooling, Compressorized Direct Expansion (DX) Systems
Cooling activates when the temperature control calculates a requirement for cooling of 100%. It is
deactivated when the cooling requirement drops below 50%. The hot gas bypass is energized on a call
for cooling unless there is also a call for dehumidification.
To aid in lubricating the compressor, the hot gas bypass solenoid is delayed for 30 seconds on the initial call for cooling and de-energized for 30 seconds during every 60 minutes of continuous operation.

2-Step Cooling, Compressorized Direct Expansion (DX) Systems with Part Coil (optional)
Cooling activates when the temperature control calculates a requirement for cooling of 50%. If the
system is designed for part coil operation, part coil is active and the hot gas bypass would be activated. At 100% cooling requirement, operation would be full coil and the hot gas bypass would be activated. When the cooling requirement drops to 75%, the system returns to part coil, and turns off the
compressor when the requirement drops to 25%.
Table 13

Cooling/dehumidification load status response
LLSV1

LLSV2
Part Coil

HGBP

1 Step Cooling Only

On

Off

On

2 Step Cooling Only

On

On

On

Dehumidifying Only

On

Off

Off

1 Step Cooling w/Dehumidifying

On

Off

Off

2 Step Cooling w/Dehumidifying

On

On

Off

GLYCOOL Cooling
When GLYCOOL cooling is available, the temperature control will calculate a total cooling requirement of 200% rather than 100%. Assuming that full GLYCOOL capacity is available, the GLYCOOL
valve opens proportionally as the requirement for cooling rises from 0 to 100%. If more than 100%
cooling is required, then the compressor is activated at 200%. If full GLYCOOL capacity is not available, then the GLYCOOL valve will be opened proportionally over a cooling requirement band equal
to the available GLYCOOL capacity. The compressor would be activated at a cooling requirement of
100% above the available GLYCOOL capacity.
For example, if the GLYCOOL capacity is 60%, then the GLYCOOL valve would be full open at 60%
cooling requirement and the compressor would be in full cooling at 160%. In order to reduce compressor cycling and prevent hunting, GLYCOOL capacity first becomes available when the entering glycol
temperature is at least 8°F (22% capacity) below the return air temperature, or 3°F below the return
air temperature for 2 hours. GLYCOOL capacity approaches 100% when the glycol temperature is 25
degrees F below the return air temperature. The system will continue to Econ-O-Cool as necessary as
long as the entering glycol temperature remains at least 3°F (0% capacity) below the return air temperature. If GLYCOOL is not available, the temperature control will operate the compressor in the
same manner as a 1-step or 2-step system without GLYCOOL. The control will not permit compressor
operation if the chilled water temperature is below the minimum chilled water temperature selected
through the SETUP OPERATION menu.

Dual Cooling Source
If dual cooling is available, the sensible cooling system operates in the same manner as a GLYCOOL
system, except that it is assumed that 100% chilled water capacity is available any time the chilled
water temperature is 3°F cooler than the return air temperature.

Chilled Water Cooling
The chilled water control valve is adjusted proportionally as the temperature control varies the
requirement for cooling from 0% to 100%.

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System Performance with Advanced Microprocessor Controls

4.1.4

Heating Operation
Electric Reheat
The two heat stages are activated when the temperature control calculates a requirement of 50% and
100%, respectively. Each stage is deactivated when the heat requirement is 25% less than the activation point.

Hot Water Reheat
The solenoid valve opens when the requirement for heating is 100% and closes when the requirement
drops below 50%.

SCR Electric Reheat (Requires Special Control Software)
The SCR (Silicon Controlled Rectifier) controller shall proportionally control the stainless steel
reheats to maintain the selected room temperature. The rapid cycling made possible by the SCR controller provides precise temperature control, and the more constant element temperature improves
heater life. During operation of the SCR control, the compressor operates continuously. The heaters
are modulated to provide temperature control.
On units equipped with SCR Reheats, unit operation can be controlled even further with DIP switch
#7 on the control board. With DIP switch #7 in the “OFF” position, or “Tight Control,” the compressor
is locked on and the SCR Reheats are modulated for very tight temperature control. In the event of a
malfunction of the SCR Reheats, the compressor will be turned off if the temperature drops to the
Low Temperature Alarm Setpoint. With DIP switch #7 in the “ON” position or “Standard Control,”
the compressor will cycle on and off as required to satisfy the requirements for cooling and dehumidification in a similar manner as a standard unit without SCR Reheats, i.e., Temperature Setpoint
PLUS Temperature Sensitivity PLUS 1°F. The SCR Reheats are modulated from 0% to 100% as
required to satisfy the requirements for heating over a control band from the Temperature Setpoint
MINUS the Temperature Sensitivity MINUS 1°F.

4.2

Humidity Control

4.2.1

Dehumidification/Humidification Required, in Percent
The humidity control program for the Advanced Microprocessor is based on a calculated % requirement for dehumidification/ humidification.

4.2.2

Response to Control Types
Proportional Control
The % requirement is determined only by the difference between the return air humidity and the
humidity setpoint. As the return air humidity rises above the humidity setpoint, the % dehumidification required increases proportionally from 0 to 100% over a humidity band equal to the humidity
sensitivity setting. The converse is true for % humidification requirement.

PID Control (Chilled Water or SCR Reheats only)
If PID control is selected, humidity is controlled in the proportional mode with the sensitivity band
being determined by the humidity sensitivity setpoint.

Intelligent Control (Chilled Water only)
If intelligent control is selected, the return air humidity is controlled at or near the humidity setpoint.
The % dehumidification/humidification required is calculated based on a set of logical “rules” that
simulate the actions of an expert human operator (see 4.3.3 - Intelligent Control (Chilled Water
only)).

4.2.3

Dehumidification Operation
1-Stage Dehumidification, Compressorized Direct Expansion (DX) Systems
Dehumidification with the standard configuration is accomplished by operating the compressor without hot gas bypass active. If system has part coil, dehumidification is accomplished by using only part
coil. If the installation has a very light sensible load, dehumidification will be inhibited at the point at
which 125% heating would be required to prevent overcooling. Dehumidification would be enabled
when the temperature increases to the point where only 50% heating is required.
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System Performance with Advanced Microprocessor Controls

4.2.4

Humidification Operation
System Activation
The humidifier (infrared or steam) is activated when the humidity control calculates a requirement of
100% humidification, and deactivated when the requirement falls below 50%.

4.3

Control Types

4.3.1

Proportional Control
This is a standard control method that maintains the room at a temperature proportional to the load.
The temperature maintained increases as the room load increases. At full load the room would be controlled at a temperature equal to the temperature setpoint plus the temperature sensitivity. If proportional control is selected, the gain is factory set and cannot be adjusted by the user. Operator inputs
are the usual setpoint and sensitivity adjustments.

4.3.2

PID Control (Chilled Water or SCR Reheats only)
The PID control combines three individual terms to determine the control output for a given set of
conditions. Note that PID control is used only for temperature. If PID control is selected, humidity
will continue to use proportional control.
The proportional (P term) is determined by the difference between the current temperature and the
control setpoint. This term is expressed in % cooling (heating) desired for each degree above (below)
the setpoint. It is adjustable from 0% to 100% per degree. The purpose of this term is to adjust the
control output for any deviation between the current temperature and the control setpoint.
The integral (I term) is determined by two things: the difference between the temperature and control
setpoint and the amount of time this difference has existed. This term is expressed in % cooling (heating) desired for each minute and degree above (below) the setpoint. It is adjustable from 0% to 100%
per degree-minute. The purpose of this term is to force the control to maintain the temperature
around the setpoint by slowly but continuously adding (subtracting) a small amount of cooling (heating) to the total control output until the temperature is at the setpoint.
The derivative (D term) is determined by the rate of change of temperature. This term is expressed in
% cooling (heating) desired for each degree per minute rise (fall) in temperature. It is adjustable from
0% to 100% per degree/min. The purpose of this term is to adjust the control output for quickly changing temperatures, thus providing an anticipation control.
All three terms are adjusted through the “select control type” menu. If PID control is selected, the
temperature sensitivity setting is not used by the control.
For optimum performance, a PID control must be adjusted or tuned according to the characteristics of
the particular space and load to be controlled. Improper tuning can cause the control to exhibit poor
response and/or hunting. The characteristics of the space and load may change seasonally, so occasional retuning is required for optimum performance.

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System Performance with Advanced Microprocessor Controls

A suggested tuning procedure is as follows:
1. Initially adjust the integral and derivative settings to 0%/ degree-min and 0% /degree/min.
2. Starting with 20% /degree, adjust the proportional setting in small increments (10% steps) until
the control sustains a constant hunting action (the temperature swings are approximately the
same amplitude from one peak to the next).
3. Note the time in minutes between peaks of adjacent temperature swings and the amplitude of the
temperature swing (degrees above the setpoint).
4. Adjust the proportional control setting to about 1/2 the value obtained in Step 2.
5. Adjust the integral setting to a value calculated by the following equation:
Approximate room load (in % full load)
Time between peaks x peak amplitude x 4

NOTE
If this calculation results in a value of less than 1%, then set the integral to 1%.
Adjust the derivative to a value calculated by the following equation:
time between peaks x 5%

The above tuning procedure is only an approximation for an initial set of adjustments and are based
on the “average” room characteristics. Your particular settings may need to be further adjusted for
optimum PID control performance. Some suggestions for additional tuning are as follows:
• If cooling output overshoot is occurring on load changes, decrease the proportional setting or the
derivative setting.
• If system hunting occurs with constant room load, decrease the integral setting.
• If the control responds too slowly, resulting in large temperature excursions on a load change,
increase the proportional setting or the derivative setting.
• If a constant temperature deviation exists between the temperature and setpoint, increase the
integral setting.

4.3.3

Intelligent Control (Chilled Water only)
The intelligent control operates from a set of general rules that define how the control output should
be adjusted for different system conditions. The rules are designed to duplicate the actions that an
experienced human operator would take if manually controlling the system.
Just as an operator might take several things into consideration before making a temperature control
decision, the intelligent control can be programmed to do likewise. For example, not only is the current temperature used in making temperature control decisions, but also conditions such as:
•
•
•
•
•
•

How fast is the temperature changing?
What direction is the temperature changing?
What is the cooling output now?
What was the cooling output in the past?
How long ago was the cooling output changed?
and other factors.

Any number of rules can be used in an intelligent control to define the controls operation under various operating conditions. Hence, several advantages are gained from this type of control over a more
standard control approach that uses a fixed mathematical equation to define the operation of the control for all conditions (such as a proportional or PID control). You can expect intelligent control to be
more efficient and precise for most applications, but system performance based on room conditions is
not as predictable as standard approaches that use a fixed equation.

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System Performance with Advanced Microprocessor Controls

4.4

Load Control Features

4.4.1

Short Cycle Control
The control system monitors the compressor and prevents it from turning on within 3 minutes of
being turned off. If this (on, off, on) occurs too often, 10 times in one hour, a Short Cycle alarm could
occur.

4.4.2

Sequential Load Activation Control
The control allows only one load output to be energized at a time on a restoration of power or microcontroller reset. Each additional load output will be activated at one second intervals until desired
operating conditions have been met.

4.5

Additional Features

4.5.1

Connecting the Analog Sensors
The sensor inputs are factory set to accept a 4 - 20 mA signal. However, the inputs can be changed by
removing the appropriate jumpers on the control circuit board. See Table 14, Figure 5 and
Figure 6.
The user supplied analog sensors MUST have their own power supply. To reduce the effects of interference from any noise source, the sensor input wiring should be shielded twisted pair and the shield
tied to earth ground at one end.
Analog input terminals for field connections are factory wired to the microprocessor board if specified
when ordered. Eight terminals are located in the field wiring compartment of the unit. Wire sensors
to the terminals as follows:
Table 14

Analog input terminals

Terminal

Signal

41

Input #1 (+)

42

Input #1 (–)

43

Input #2 (+)

44

Input #2 (–)

45

Input #3 (+)

46

Input #3 (–)

47

Input #4 (+)

48

Input #4 (–)

Consult your Liebert supplier for a field installation kit to add these connections after unit delivery, if
required.
Table 15

Additional connections available after unit delivery
Input #1

Input #2

Input #3

Input #4

4–20 mA

Jumper P50.1 & 2
and P50.3 & 4

Jumper P50.5 & 6
and P50.7 & 8

Jumper P50.9 &10
and P50.11 & 12

Jumper P50.13 &14
and P50.15 & 16

0–5 VDC

Jumper P50.1 & 2

Jumper P50.5 & 6

Jumper P50.9 & 10

Jumper P50.13 & 14

0–10 VDC

NO Jumper
on P50.1 & 2
and P50.3 & 4

NO Jumper
on P50.5 & 6
and P50.7 & 8

NO Jumper
on P50.9 &10
and P50.11 & 12

NO Jumper
on P50.13 & 14
and P50.15 & 16

34

System Performance with Advanced Microprocessor Controls

Figure 5

Analog input jumpers
Analog input jumper location

ENLARGED AREA

4.5.2

Water Detection Display
The water detection display is designed to graphically display the location of water under a raised
floor when connected to an LT750 water detection system. The graphical floor plan screen shows a 30
x 16 grid. Each square represents one standard floor tile (approximately 2 ft. x 2 ft.).

Installation—LT750 DIP Switch Settings
Install the LT750 following the instructions in the LT750 user manual. The following additional
switch selections should be made when connecting to an Advanced Microprocessor control:
• DIP SW3-4—Off-(water alarm relay energizes for alarm)
• DIP SW3-5—Off-(cable fault relay energizes for alarm)
• Switch 1—Off-(LT750 sources power for 4-20 mA loop)
Figure 6

Connecting the LT750

TB6

2
1

+

TB5
fault

3
2
1

NO
NC
C

3
TB4 2
water 1

NO
NC
C

41
42
43
44
45
46
47
48
24
50
51
55
56

LT750

Environmental Unit

35

System Performance with Advanced Microprocessor Controls

Physical Connections
Figure 6 shows the 4-20 mA output of LT750 connected to Analog Input #1 (41 and 42) on the external inputs terminal strip. This strip is provided on units ordered with analog inputs. (If this strip is
not installed, there is a field installation kit available from your Liebert representative.)
The 4-20 mA output of the LT750 must be connected to the first analog input, as shown.
TB4 is the water detected relay output. It can be connected to any one of the four special alarm inputs.
TB5 is the cable fault relay output. It can also be connected to any one of the four special alarm
inputs.

Setup
(The following description assumes the wiring connections as shown above.) First, verify that special
alarms 1 and 2 are ENABLED to either WARNING or URGENT type. Do this by selecting VIEW/SET
ALARMS from the Main Menu. Then, select SETUP ALARMS. Follow the instructions on the display
to select the required type for CUSTOM ALARM #1 and CUSTOM ALARM #2 if not already set.
Next, select the alarm message for CUSTOM ALARM #1 and #2. From the Main Menu, select VIEW/
SET ALARMS. Then, select SETUP CUSTOM ALARMS. Then, select SETUP CUSTOM ALARM
TEXT. Define CUSTOM ALARM #1 to be CUSTOM 1. (CUSTOM 1 is the default message that will be
displayed if a message has never been programmed.) Next, select the text for custom alarm #2 to be
WATER UNDER FLOOR. Now, change the message CUSTOM 1 to LT750 CABLE FAULT. This is
done by selecting the CHANGE CUSTOM TEXT 1 menu item in the SETUP CUSTOM ALARMS
menu. Follow the instructions on the screen to change the message.
The slope and intercept values of Analog Input #1 are used to calculate the location of water. These
values should initially be set to zero. The default values are zero, but it may be a good idea to verify
those values. They can be viewed by selecting ANALOG/DIGITAL INPUTS from the Main Menu,
then SETUP ANALOG INPUTS.
See 3.4.6 - Setup Water Detect Floor Plan for more information.

Calibration
Calibration should not be required for most installations. The accuracy of this display is approximately 1%.
The display is calibrated by the slope and intercept values of Analog Input #1. The position of the
water is calculated from the analog output of the LT750 using this formula:
position = analog reading/full scale reading x (measured length + slope) + intercept

position is the distance from the LT750 to the position of the detected water.
measured length is the length of the cable which is calculated automatically when the layout is
defined. The units for these values are in floor tiles.
The intercept value read from Analog Input #1 is added to the measured position of a water indication
to determine which tile to highlight. For example, if water is displayed under the seventh tile but
determined to be under the fifth tile, set the offset value to -2 tiles. Use the intercept value to correct
errors close to the start of the cable.
Accuracy errors farther out on the cable should be corrected using Analog Input #1's slope value. This
value effectively adjusts the measured length of the cable. Increasing the effective length of cable will
increase the distance of the water and move the highlighted tile farther along the cable, and vice
versa. Unlike the intercept, which adjusts by the same amount for all locations on the cable, the slope
increases its effect for larger distances.
The best procedure to calibrate the cable would be to first simulate water close to the LT750, about
five tiles out. Adjust the intercept to get the correct reading. Next, simulate water five tiles from the
end. Adjust the slope to get the correct reading.

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System Performance with Advanced Microprocessor Controls

4.6

Communications
The control system uses a two-wire, RS-422 channel to communicate with remote monitoring systems
via Liebert Site Products. This communication, directly out of the control, uses a proprietary protocol.
Your unit can have a variety of different Site Product devices wired to this port depending on the
monitoring system you are using. Consult the user manual of the appropriate device for specific
installation and operation information.

Liebert Monitoring Devices and Software
• SiteScan Centralized Monitoring System—Stand-alone facility monitoring system
• SiteLink BMS Interface Module—For Modbus or BACnet communication to a third-party monitoring system.
• OpenComms Network Interface Card—For Ethernet connection using SNMP protocol.
• OpenComms Nform—Software package to monitor SNMP devices
• Environmental DO Interface Card—For discrete outputs of status and alarm conditions.
• Mini-Remote—Stand-alone individual unit remote monitor
• ECA2 Communication Adapter—For remote service monitoring directly or via a modem.

37

Alarm Descriptions

5.0

ALARM DESCRIPTIONS
The Advanced Microprocessor (A) and the Advanced Microprocessor with Graphics (G) Control systems will audibly and visually annunciate all ENABLED alarms, including the four custom alarms.
With the Advanced & Advanced with Graphics Controls, the customer alarms can be from the
optional alarm list and/or can have their own fully custom text. Two alarms may be selected as custom for the Advanced Microprocessor and four can be custom for Advanced Microprocessor with
Graphics. The custom alarm inputs are 24 VAC, which is available from the Liebert unit. Alarms are
wired from terminal 24 through a normally open contact to locations 50, 51, 55, and 56, respectively,
for alarms 1 through 4.
The Advanced and Advanced with Graphics alarms can be delayed from 0 to 255 seconds (for
Advanced see Setup Alarms on page 9; for Advanced with Graphics, see 3.4.3 - Setup Alarms).
The Advanced alarms can be ENABLED or DISABLED and can also be programmed to energize the
Common Alarm Relay or to “alarm only” and not energize the Common Alarm Relay.
The Advanced Microprocessor with Graphics alarms can be selected as WARNING, URGENT, or DISABLED. If selected to be a WARNING, they are annunciated after the Time Delay, but do not energize the Common Alarm Relay. If selected as URGENT, they are annunciated after the Time Delay as
a WARNING alarm and then re-annunciated after a user programmable period from 0 minutes to 999
hours as an URGENT alarm. When annunciated as an URGENT alarm, the Common Alarm Relay is
activated. The custom alarm inputs of the Advanced Microprocessor with Graphics can be designated
to be “Status Only.” As Status Only the custom alarm input is referenced as a digital input and is no
longer treated as an alarm. It is for monitoring only and can be reviewed by selecting “ANALOG/DIGITAL INPUTS.”
When a new alarm occurs, it is displayed on the screen and the audible alarm is activated. If communicating with a Liebert Site Product, the alarm is also transmitted. The display will also show a message to “PRESS ENTER KEY TO SILENCE” the alarm. After the alarm is silenced, the display will
return to the Normal Status Display. For the Advanced Microprocessor with Graphics, the bell and
hammer are shown at the top of the Normal Status Display. For the Advanced Microprocessor, the
bottom line will display the number of Active Alarms. The active alarms can be reviewed on the
Advanced Microprocessor Controls by selecting “ACTIVE ALARMS.”
The alarms can also be silenced through communications with a Liebert Site Products unit. Most
alarms will reset automatically when the alarm condition is no longer present and only after it has
been acknowledged by being “Silenced.” The exceptions are:
1. The three software alarms: Loss of Power, Low Suction Pressure, and Short Cycle, which reset
automatically 90 minutes after being “Silenced” or acknowledged.
2. Some alarms such as overloads and high pressure switches may require a manual reset
depending on your model.
A history of 10 alarms for Advanced (see 2.4.3 - Alarm History Log) and 60 alarms for Advanced
with Graphics (see 3.4.2 - Alarm History Log) is retained in nonvolatile memory.
This section provides a definition of each available alarm. Troubleshooting suggestions are included.
Refer to 7.0 - Troubleshooting for more details. If you need assistance with your environmental control system, contact your Liebert supplier.

5.1

Standard Alarms

5.1.1

Change Filter
Periodically, the return air filters in the environmental units must be changed. The Change Filter
alarm notifies the user that filter replacement is necessary. A differential air pressure switch closes
when the pressure drop across the filters becomes excessive. The switch is adjustable using the procedure on the switch label.

38

Alarm Descriptions

5.1.2

Compressor Overload
An optional tri-block overload device can be used for the compressor. Compressor overload may be
manual or automatic reset, depending on your model. Overload is located at the electric connection
box on the compressor.

5.1.3

Custom Alarms
Custom alarm messages are programmed at the LCD display. The alarms may be specified by the
customer at the time of order. Additional devices and wiring may be required at the factory or by others. The message displayed may be included in this alphabetical list of alarms, or it may be customized text (for up to two alarms). If customized text is used, customer maintenance personnel should be
informed of the alarm function and corrective action required.

5.1.4

High Head Pressure
Compressor high head is monitored with a pressure switch. One SPDT pressure switch is used for the
compressor in the unit. If head pressure exceeds 360 PSIG, the switch opens the compressor contactor
and sends an input signal to the control. On a self-contained system, the head pressure switch located
at the compressor requires a manual reset and the alarm condition to be acknowledged on the front
display panel. On a split system, the high head pressure condition is acknowledged by pressing the
alarm silence button that will clear the alarm if the high head pressure condition no longer exists. On
a split system, if the compressor is off for 1 hour, the control goes into a special "cold start mode." In
the cold start mode on a call for cooling or dehumidification, the Liquid Line Solenoid Valve (LLSV) is
energized. If the high pressure switch does NOT trip within 10 seconds, the control returns to normal
operation of monitoring the high head pressure switch for three occurrences in a 12-hour period. It is
a rolling timer; and after the third high head alarm occurs and is acknowledged by the user, it will
lock off the compressor. If while in the cold start mode, the high head pressure switch DOES trip
within 10 seconds of the activation of the LLSV, the control does not annunciate the alarm. The control will turn off the LLSV and delay 10 seconds. The control will permit this occurrence two more
times or a total of three times. If on the fourth try the high head pressure switch trips within 10 seconds, the control will annunciate the alarm, turn off the LLSV, wait for the user to acknowledge the
alarm, and hold the compressor off for three minutes, which is the normal short cycle control. On the
third occurrence, the control will lock the compressor off until the control power is reset.
On air cooled systems, check for power shut off to the condenser, condenser fans not working, defective head pressure control valves, closed service valves, dirty condenser coils, and crimped lines. Also,
make sure that when the compressor contactor is energized, the side switch on the contactor closes to
energize the control circuit on the air cooled condenser.
On water/glycol/GLYCOOL systems, check water regulating valves. Verify water/glycol flow (are
pumps operating and service valves open?). Is water tower or drycooler operating? Is the coolant temperature entering the condenser at or below design conditions? Is relay R5 operating during cooling to
turn on the drycooler?

5.1.5

High Humidity
The return air humidity has increased to the High Humidity Alarm setpoint. Is the unit setup for
dehumidification (check DIP switch)? Check for proper setpoints. Does the room have a vapor barrier
to seal it from outdoor humidity? Are doors or windows open to outside air? Run diagnostics to make
sure the cooling system is working properly (the cooling system dehumidifies).

5.1.6

High Humidity and Low Humidity (Simultaneously)
If these two alarms are displayed at the same time, the humidity input signal is lost. Dashes will be
displayed for the humidity reading. The control system will deactivate humidification and dehumidification. Check for a disconnected cable or a failed sensor.

5.1.7

High Temperature
If the return air temperature has increased to the High Temperature Alarm setpoint, check for proper
setpoints. Is the room load more than the unit can handle (is the unit capacity too small)? Run diagnostics to make sure all cooling components are operating (compressor and/or valves).

39

Alarm Descriptions

5.1.8

High Temperature and Low Temperature (Simultaneously)
If these two alarms are displayed at the same time, the temperature input signal is lost (or the
humidity is out of sensor range: 15 to 85% RH). Dashes will be displayed for the temperature reading.
The control system will initiate 100% cooling. Check for a disconnected cable or a failed sensor.

5.1.9

Humidifier Problem
Infrared Humidifiers
This alarm is activated by the high water float switch in the humidifier pan assembly. The high water
float switch is normally closed and opens upon alarm condition. Check for drain clog and, if present,
clean drain. Check for float switch stuck high; replace the switch as necessary. Check for proper operation of the humidifier water makeup valve.

Steam Generating (Canister) Humidifiers
This alarm is activated by a signal from the humidifier control indicating that the canister needs to be
replaced.

5.1.10 Loss of Air Flow
A differential air pressure switch is used to indicate loss of air flow in Challenger 3000 units.
Check for blockage of unit air outlet or inlet. Check blower motor fuses and overload reset. Check for
broken belts. Make sure blower wheels are tight to shaft. Run diagnostics to see if the fan contactor is
working properly.

5.1.11 Loss of Power
If the unit has lost power, or the disconnect switch was turned off before the unit ON switch was
pressed (to turn the unit Off), this local alarm will occur when power is restored to the unit. A Liebert
remote monitoring unit (optional) will immediately indicate loss of power.

5.1.12 Low Humidity
If the return air humidity has decreased to the Low Humidity Alarm setpoint, check to make sure
that the unit is setup for humidification (check DIP switch). Check for proper setpoints. Does the
room have a vapor barrier to seal it from outdoor humidity? Are doors or windows open to outside air?
Run diagnostics to make sure the humidifier system is working properly.

5.1.13 Low Suction Pressure
A pressure switch monitors the suction pressure at the compressor inlet to monitor whether pressure
has dropped below a factory preset point while the compressor is in cooling operation. When pressure
drops below a factory preset point, the switch opens. After the positive start kit time delay, and the
switch stays open for five minutes, the alarm is activated. The alarm stays active for 90 minutes.
Look for conditions that would cause loss of refrigerant. Check for piping problems such as leaks or
crimped lines. Check for inoperative components such as liquid line solenoid valve, low pressure
switch, expansion valve, and head pressure control valve. Check for closed service valves in the liquid
line or at the condenser or receiver.

5.1.14 Low Temperature
If the return air temperature has decreased to the Low Temperature Alarm setpoint, check for proper
setpoints. Run diagnostics to make sure all heating components are operating (contactors and
reheats). Are reheats drawing the proper current? (See nameplate for amp rating.)

5.1.15 Main Fan Overload
An optional tri-block overload is required for this alarm, and may or may not replace internal motor
overload, depending on your model. The overload device is located next to the main fan contactor in
the line voltage section. The alarm is activated when the overload is tripped.

40

Alarm Descriptions

5.1.16 Short Cycle
On compressorized systems, if the compressor has exceeded 10 cooling starts in one hour or if the
compressor has cycled five times in 10 minutes on the low pressure switch during non-cooling, the
Short Cycle alarm will occur. This can be caused by low refrigerant level (but not low enough to activate Low Suction Pressure alarm) or room cooling load is small compared to capacity of the unit.
Check for leaks, crimped lines, and defective components. If room load is low, increase sensitivity to
reduce cycling (proportional control). On GLYCOOL units, dirty filters can cause the coil freeze stats
to cycle the compressor.

5.2

Optional/Custom Alarms

5.2.1

Loss of Water Flow
Available only with 3-way valves and occurs when no water flow is detected in the chilled water or
condenser water supply line. An optional flow switch is required for this alarm. Check for service
valves closed, pumps not working, etc.

5.2.2

Smoke Detected
Smoke is detected in the return air by an optional Liebert Smoke Detector. Check for source of smoke
or fire, and follow appropriate emergency procedures.

5.2.3

Standby GC Pump On
The primary pump has failed, and the standby pump is activated (glycol cooled and GLYCOOL units
only).
Check for problems with the primary pump (fuses blown, motor burnout, service valve shut, stuck
check valve, impeller damage, etc.).

5.2.4

Standby Unit On
The primary environmental control system has had an alarm condition, and the standby system is
activated.

5.2.5

Water Under Floor
Water is detected by an optional Liebert Water Detection System. Check under the raised floor for
water or other leaks.
NOTE
The alarms are specified by the customer at the time of order. All alarms will report to a
Liebert remote monitoring unit. Additional devices and wiring may be required at the factory
for some of the alarms.

41

Component Operation and Maintenance

6.0

COMPONENT OPERATION AND MAINTENANCE

6.1

System Testing

6.1.1

Environmental Control Functions
The performance of all control circuits can be tested by actuating each of the main functions. This is
done by temporarily changing the setpoints.

Cooling
To test the cooling function, set the setpoint for a temperature of 10°F (5°C) below room temperature.
A call for cooling should be seen and the equipment should begin to cool. A high temperature alarm
may come on. Disregard it. Return setpoint to the desired temperature.

Heating
Reheat may be tested by setting the setpoint for 10°F (5°C) above room temperature. A call for heating should be seen and the heating coils should begin to heat. Disregard the temperature alarm and
return the setpoint to the desired temperature.

Humidification
To check humidification, set the humidity setpoint for an RH 10% above the room humidity reading.
For infrared humidifiers, the infrared element should come on. For steam generating humidifiers, you
will immediately hear the clicks as it energizes. After a short delay, the canister will fill with water.
The water will heat and steam will be produced. Return the humidity setpoint to the desired humidity.

Dehumidification
Dehumidification can be checked by setting the humidity setpoint for an RH 10% below room relative
humidity. The compressor should come on. Return humidity setpoint to the desired humidity.

Proportional Heating/Cooling/ Dehumidification
On Chilled Water, GLYCOOL (Econ-O-Cycle, Free Cool, GLYCOOLING cycle) models, and models
with hot water reheat, the microprocessor is capable of responding to changes in room conditions.
These systems utilize either a 2- or 3-way valve activated by a proportioning motor.
For cooling and dehumidification, the microprocessor will respond by positioning the valve proportionally to match the needs of the room. Full travel of the valve takes place within the range of the
sensitivity setting. During dehumidification, full travel of the valve takes place within 2% RH.
For hot water reheat, the microprocessor will respond by positioning the hot water valve proportionally to match the needs of the room. Full travel of the valve takes place within 1°F with each 0.1°F
resulting in 10% valve travel.

Electric Panel
The electric panel should be inspected for any loose electrical connections.

!

CAUTION

Be sure that power to the unit is shut down before attempting to tighten any
fittings or connections.

Control Transformer and Fuses
The control system is divided into four separate circuits. The control voltage circuits are individually
protected by fuses located on the transformer/fuse board. If any of the fuses are blown, first eliminate
shorts, then use spare fuses supplied with unit. Use only type and size of fuse specified for your unit.
The small isolation transformer on the board supplies 24 volts to the main control board. The transformer is internally protected. If the internal protector opens, the transformer/fuse board must be
replaced. Also check the control voltage fuse on the main control board before replacing the transformer/fuse board.

Fan Safety Switch
The Fan Safety Switch is located in the low voltage compartment and consists of a diaphragm switch
and interconnecting tubing to the blower scroll. The Fan Safety switch is wired directly to the control
circuit to activate the alarm system if the airflow is interrupted
42

Component Operation and Maintenance

Firestat
The optional firestat is a bimetal operated sensing device with a normally closed switch. This device
will shut down the entire unit when the inlet air temperature exceeds a preset point. It is connected
between terminals 1 and 2 at plug P39.

Smoke Detector
The optional smoke detector power supply is located on the base of the upflow units, and at the top of
downflow units. It is constantly sampling return air through a tube. No adjustments are required.

Water Detection Sensor

!

CAUTION

Do not use near flammable liquids or for flammable liquid detection.

The optional water detection devices available are a point leak detection sensor and a zone leak detection kit.
Figure 7

Liebert leak detection units
LT460 Zone Leak
Detection Kit

Liquitect Point Leak
Detection Sensor

The point leak detection sensor provides leak detection at a critical point. A simple two-wire connection signals the alarms at a Liebert environmental unit or at a monitoring panel. Run wires to the
Liebert unit and connect them to terminals 24 and 51, 55 or 56. Use NEC Class 2, 24V wiring. The
sensor contains a solid state switch that closes when water is detected by the twin sensor probes. The
sensor is hermetically sealed in all thread PVC nipple and is to be mounted where water problems
may occur. The sensor should be located 6-8 feet (2-2.5m) from the environmental control unit in a
wet trap or near a floor drain. It should not be mounted directly under the unit.
Figure 8

Recommended liquid sensor locations
Liebert unit

Recommended
Liquitect location
Floor drain

43

Component Operation and Maintenance

The zone leak detection kit provides leak detection for a defined zone. This kit is ideal for perimeter
sensing or serpentine coverage of small areas. A simple, two-wire connection signals the alarms at a
Liebert environmental unit or at a monitoring panel. Run wires to the Liebert unit and connect them
to terminals 24 and 51, 55 or 56. The sensor utilizes Liebert's LT500Y leak detection cable. The kit is
offered with five different lengths of cable sized specifically for the type of Liebert Environmental unit
(see matrix below). Refer to matrix below for the recommended location of leak detection cable.
Table 16

Zone leak detection kit installation scenarios
Scenarios
Upflow Unit
Detection
around
entire unit

Upflow Unit
Detection on sides
and
in front of unit

2-ft clearance
in front

2-ft clearance
in front

Downflow Unit
Detection
around
entire unit

Downflow Unit
Detection on sides
and
in front of unit

6-ft clearance
in front

6-ft clearance
in front

Distance From Unit
Distance:
In back
On sides
In front

2 ft
2 ft
2 ft

Unit
(footprintin.)
Challenge
r
(32.5 x
32.5)

1 ft
1 ft
6 ft

No cable behind
1 ft
6 ft

LT460-Z30

LT460-Z25

No cable behind
2 ft
2 ft
Part Number

LT460-Z30

LT460-Z20

Remote Shutdown
A connection point is provided for customer supplied remote shutdown devices. This terminal strip is
located at the top of upflow units, and at the base of downflow units. Terminals 37 and 38 on the terminal strip are jumpered when no remote shutdown device is installed.

6.2

Filters
Filters are usually the most neglected item in an environmental control system. To maintain efficient
operation, they should be checked monthly and changed as required. Because replacement intervals
vary with environmental condition and filter type, each unit is equipped with a filter clog switch. This
warns of restricted airflow through the filter compartment by activating the Change Filter alarm.
Turn power off before replacing filters.
Challenger 3000 filters are 28-1/2" by 29-1/2", either 2" or 4" thick, plus an optional 2" thick pre-filter.
The filter is replaced from the front of the unit. On upflow units, the filter is vertical, in front of the
lower compartment. Pull the filter out toward you to remove it. On downflow units, the filter is horizontal, above the electrical panel. Slide the filter out toward you to remove it.
After replacing the filter(s), test the operation of the filter clog switch. Turn the adjusting screw
counter clockwise to trip the switch — this will energize the Change Filter alarm. To adjust the
switch proceed as follows: With the fan running, set the switch to energize the light with clean filters.
The unit panels must all be in place and closed to accurately find this point. Then turn the adjusting
knob one turn clockwise, or to the desired filter change point.

44

Component Operation and Maintenance

6.3

Blower Package
Periodic checks of the blower package include: belt, motor mounts, fan bearings, and impellers.

6.3.1

Fan Impellers and Bearings
Fan impellers should be periodically inspected and any debris removed. Check to see if they are
tightly mounted on the fan shaft. Rotate the impellers and make sure they do not rub against the fan
housing.
Bearings used on the units are permanently sealed and self-lubricating. They should be inspected for
signs of wear when the belt is adjusted. Shake the pulley and look for movement in the fan shaft. If
any excessive movement is noticed, bearings should be replaced. However, the cause of the wear must
be determined and corrected before returning the unit to operation.

6.3.2

Belt
The drive belt should be checked monthly for signs of wear and proper tension. Pressing in on belts
midway between the sheave and pulley should produce from 1/2" to 1" (12 to 25 mm) of movement.
Belts that are too tight can cause excessive bearing wear.
Belt tension can be adjusted by raising or lowering the fan motor base. Loosen nut above motor
mounting plate to remove belt. Turn nut below motor mounting plate to adjust belt tension. If belt
appears cracked or worn, it should be replaced with a matched belt (identically sized). With proper
care, a belt should last several years.
NOTE
After adjusting or changing the belt, always be certain that motor base nuts are tightened.
The bottom adjustment nut should be finger tight. The top locking nut should be tightened
with a wrench.

6.3.3

Air Distribution
All unit models are designed for constant volume air delivery. Therefore any unusual restrictions
within the air circuit must be avoided. Refer to the following table for recommended free area for
proper air flow.
Table 17

Recommended free area ft2 (m2) for grilles or perforated panels at output velocities of
550 and 600 fpm (2.8 and 3.1 m/s)
550 FPM
(2.8 m/s)

600 FPM
(3.1 m/s)

3 Ton

2.5 (0.22)

2.3 (0.21)

5 Ton

3.8 (0.34)

3.5 (0.33)

3 Ton

2.9 (0.27)

2.6 (0.24)

5 Ton

3.5 (0.33)

3.3 (0.31)

Model
60 Hz Units

50 Hz Units

Grilles used in raised floors vary in size, the largest being 18" x 6" (46 cm x 15 cm). This type of grille
has approximately 56 in2 (361 cm2) of free area. Perforated Panels are usually 2' x 2' (61 cm x 61 cm)
and have a nominal free area of approximately 108 to 144 in2 (697 to 929 cm2).
NOTE
Absolutely avoid any under-floor restrictions such as clusters of cables or piping. Whenever
possible, cables and pipes should be run parallel to the air flow. Never stack cables or piping.

45

Component Operation and Maintenance

6.4

Refrigeration System
Each month, the components of the refrigeration system should be inspected for proper function and
signs of wear. Since, in most cases, evidence of malfunction is present prior to component failure, periodic inspections can be a major factor in the prevention of most system failures.
Refrigerant lines must be properly supported and not allowed to vibrate against ceilings, floors or the
unit frame. Inspect all refrigerant lines every six months for signs of wear and proper support. Also
inspect capillary and equalizer lines from the expansion valve and support as necessary.
Each liquid line has a sight glass that indicates liquid refrigerant flow and the presence of moisture.
Bubbles in the sight glass indicate a shortage of refrigerant or a restriction in the liquid line. The
moisture indicator changes from green to yellow when moisture is present in the system.

6.4.1

Suction Pressure
Suction pressure will vary with load conditions. The low pressure switch will shut the compressor
down if suction pressure falls below the cut-out setting. High suction pressure reduces the ability of
the refrigerant to cool compressor components and can result in compressor damage. Minimum (pressure switch cut-out setting) and maximum (design operating) suction pressures are in Table 18.
Table 18

Suction pressures
Minimum
PSIG (kPa)
R–22

Maximum
PSIG (kPa)
R–22

Air w/FSC
(Fan Speed Control)

15 (103)

90 (620)

Air w/Lee-Temp Control
(Floodback head
pressure control)

20 (137)

90 (620)

Water Cooled

20 (137)

90 (620)

Glycol Cooled

20 (137)

90 (620)

System

6.4.2

Discharge Pressure
Discharge Pressure can be increased or decreased by load conditions or condenser efficiency. The high
pressure switch will shut the compressor down at its cut-out setting. Refer to Table 19, below.
Table 19

Discharge pressures
System Design

Discharge Pressure
PSIG (kPa)

Air Cooled
Water/Glycol Cooled

6.4.3

260 (1795)
65-75°F (18-24°C) fluid

210 (1450)

85°F (29°C) fluid

225 (1550)

115°F (46°C) fluid

295 (2035)

Maximum

330 (2275)

High Pressure Cut-Out

360 (2482)

Superheat
Superheat can be adjusted by the Thermostatic Expansion Value (TEV). To determine superheat:
1.
2.
3.
4.
5.

Measure the temperature of the suction line at the point the TEV bulb is clamped.
Obtain the gauge pressure at the compressor suction valve.
Add the estimated pressure drop between bulb location and suction valve.
Convert the sum of the two pressures to the equivalent temperature.
Subtract this temperature from the actual suction line temperature. The difference is superheat.

46

Component Operation and Maintenance

6.4.4

Thermostatic Expansion Valve
Operation
The thermostatic expansion valve performs one function. It keeps the evaporator supplied with
enough refrigerant to satisfy load conditions. It does not effect compressor operation.
Proper valve operation can be determined by measuring superheat. If too little refrigerant is being fed
to the evaporator, the superheat will be high; if too much refrigerant is being supplied, the superheat
will be low. The correct superheat setting is between 10 and 15°F (5.6 and 8.3°C).

Adjustment
To adjust the superheat setting, proceed as follows:
1. Remove the valve cap at the bottom of the valve.
2. Turn the adjusting stem counterclockwise to lower the superheat.
3. Turn the adjusting stem clockwise to increase the superheat.
NOTE
Make no more than one turn of the stem at a time. As long as 30 minutes may be required
for the new balance to take place.

6.4.5

Hot Gas Bypass Valve
Operation
The hot gas bypass is inserted between the compressor discharge line and the leaving side of the
expansion valve through the side outlet distributor. The system, with normal operation when the
evaporator is under full load, will maintain enough pressure on the leaving side of the hot gas valve to
keep the valve port closed.
If the load on the evaporator decreases, the evaporator will get colder. When the coil is too cold, the
internal pressure in the evaporator drops and allows the hot gas bypass valve to open. Hot gas then
mixes with the liquid coolant on the discharge side of the expansion valve raising the temperature
and pressure in the evaporator. The net result is a reduction in the cooling capacity of the unit to
match the load.
To aid in lubricating the compressor, the hot gas bypass solenoid is delayed for 30 seconds on the initial call for cooling and de-energized for 30 seconds during every 60 minutes of continuous operation.

Adjustment
Upon deciding what evaporator temperature is desired, the following procedure should be used to
adjust the hot gas bypass valve:
1.
2.
3.
4.
5.
6.
7.
8.

Install the suction and discharge pressure gauge.
Adjust the temperature setpoint to call for cooling so that the refrigeration compressor will run.
Remove the TOP adjusting nut from the valve.
Insert an Allen wrench in the brass hole at top of the valve in adjusting port, and turn
CLOCKWISE if a higher evaporator temperature is required.
After obtaining the suction pressure required, reinstall the cap tightly making sure there are no
leaks.
Let the evaporator operate for approximately 10 to 15 minutes to make sure the suction pressure
is within the desired range.
There will be a fluctuation of approximately 3 to 6 PSIG (21 to 41 kPa) on the evaporator due to
the differential on the hot gas bypass.
Return the temperature setpoint to desired number.

47

Component Operation and Maintenance

6.4.6

Air Cooled Condenser
Restricted airflow through the condenser coil will reduce the operating efficiency of the unit and can
result in high compressor head pressure and loss of cooling.
Clean the condenser coil of all debris that will inhibit air flow. This can be done with compressed air
or commercial coil cleaner. Check for bent or damaged coil fins and repair as necessary. In winter, do
not permit snow to accumulate around the sides or underneath the condenser.
Check all refrigerant lines and capillaries for vibration isolation. Support as necessary. Visually
inspect all refrigerant lines for signs of oil leaks.

Checking Refrigerant Charge (Lee–Temp/Flood Back Head Pressure Control)
The system refrigerant level must be checked periodically. To do so:
1. Adjust temperature setpoint in the unit so that the compressor will run continuously.
2. The refrigerant level is visible through two sight glasses on the receiver and will vary with
ambient temperature.
a. 40°F (4.4°C) and lower — Midway on the bottom sight glass.
b. 40 to 60°F (4.4 to 15.6°C) — Bottom sight glass should be clear with liquid.
c. 60°F (15.6°C) and above — Midway on the top sight glass.
3. Return temperature setpoint to desired number.
Figure 9

Outdoor fan/condenser configuration
FAN SPEED CONDENSER

Electric service
supplied by others
*B
Hot gas line
Secure each leg to condenser
frame at all points shown using
hardware provided.

Liquid line
LEE-TEMP CONDENSER

Lee-Temp heater pad
connection box

*B
Hot gas line

Liquid line

Electric
service
supplied by
others

*B - Inverted traps are to be field-supplied and installed (typ). When installing traps, provide
clearance for swing end of access door. Traps are to extend above base of coil by a
minimum of 7-1/2" (190 mm).

48

Component Operation and Maintenance

6.4.7

Water/Glycol Cooled Condensers
Coaxial Condenser
Each water or glycol cooled module has a coaxial condenser which consists of a steel outside tube and
a copper inside tube.
Coaxial condensers do not normally require maintenance or replacement if the water supply is clean.
If your system operates at high head pressure with reduced capacity, and all other causes have been
eliminated, the coaxial condenser may be obstructed and needs to be replaced.

Regulating Valve
The water regulating valve automatically regulates the amount of fluid necessary to remove the heat
from the refrigeration system, permitting more fluid to flow when load conditions are high and less
fluid to flow when load conditions are low. The valve consists of a brass body, balance spring, valve
seat, valve disc holders, capillary tube to discharge pressure, and adjusting screw.

Standard Valve - 150 psig (1034 kPa) system for 3 & 5 ton units (Johnson Controls Valve)
High Pressure Valve - 350 psig (2413 kPa) system for 5 ton units (Johnson Controls Valve)
Adjustment—The valve may be adjusted with a standard refrigeration service valve wrench or
screw driver. Refer to Table 19 for recommended refrigerant pressures.
To lower the head pressure setting, turn the square adjusting screw clockwise until the high pressure
gauge indicates the desired setting.
To raise the head pressure setting, turn the adjusting screw counterclockwise until the desired setting is obtained.
Figure 10 Johnson Controls valve adjustment
Range
Spring
Valve
Spring
Guide

Range Adjustment Screw

Top
Retainer
Insert screwdrivers under
the valve spring guide.

Manual Flushing—The valve may be flushed by inserting a screwdriver or similar tool under the
two sides of the main spring and lifting. This action will open the valve seat and flush any dirt particles from the seat. If this fails, it will be necessary to disassemble the valve and clean the seat.
49

Component Operation and Maintenance

High Pressure Valve - 350 PSIG System (2413 kPa) for 3 Ton Units (Metrex Valve)
Adjustment—The valve may be adjusted using a 1/8" diameter rod. Turn adjusting collar nut counterclockwise to raise head pressure. Turn it clockwise to lower head pressure. Rotation directions are
as viewed from top of valve spring housing.
Figure 11 Metrex valve adjustment

Adjusting Collar Nut

Manual Flushing—The valve may be flushed by rotating the socket head screw clockwise. This
screw must be in the OUT position (counterclockwise) for normal valve operation.
Valve Disassembly
1. Shut off the water supply by using isolating valves.
2. Relieve the tension on the main spring by turning the adjusting screw (or collar) as far as it will
go (provide a container to catch water below the valve).
3. Remove four screws extending through the main spring housing.
4. Remove the center assembly screws for access to all internal parts.
5. Clean the seat if possible. If the seat is pitted or damaged, replace the valve rubber disc and valve
seat.
6. After valve is reassembled check for leaks.
7. Readjust head pressure control.
Testing Function of Valve—When the refrigeration system has been off for approximately 10 to 15
minutes, the water flow should stop.
If the water continues to flow, the valve is either improperly adjusted (with head pressure too low) or
the pressure sensing capillary is not connected properly to the condenser.

Glycol Solution Maintenance
It is difficult to establish a specific schedule of inhibitor maintenance since the rate of inhibitor depletion depends upon local water conditions. Analysis of water samples at time of installation and every
six months should help to establish a pattern of depletion. A visual inspection of the solution and filter residue is often helpful in judging whether or not active corrosion is occurring.
The complexity of water caused problems and their correction makes it important to obtain the advice
of a water treatment specialist and follow a regularly scheduled maintenance program. It is important to note that improper use of water treatment chemicals can cause problems more serious than
using none.
Proper inhibitor maintenance must be performed in order to prevent corrosion of the glycol system.
Consult glycol manufacturer for testing and maintenance of inhibitors. Do not mix products from different manufacturers. For further details, refer to filling instructions in the installation manual, Liebert part number SL-11925.

50

Component Operation and Maintenance

6.4.8

Compressor Functional Check
The following diagnostic procedure should be used to evaluate whether the compressor is working
properly.
1. Proper voltage to the unit should be verified.
2. The normal checks of motor winding continuity and short to ground should be made to determine
if the inherent overload motor protector has opened or if an internal motor short or ground fault
has developed. If the protector has opened, the compressor must be allowed to cool sufficiently to
allow it to reset.
3. Proper indoor and outdoor blower/fan operation should be verified. Condenser glycol flow should
be verified.
4. With service gauges connected to suction and discharge pressure fittings, turn on the compressor.
If suction pressure falls below normal levels, the system is either low on charge or there is a flow
blockage in the system.
5. If suction pressure does not drop and discharge pressure does not rise to normal levels, reverse
any two of the compressor power leads and reapply power to make sure compressor was not wired
to run in reverse direction. If pressures still do not move to normal values, system is properly
charged and solenoid valves function, the compressor is faulty. Reconnect the compressor leads as
originally configured and use normal diagnostic procedures to check operation of the reversing
valve.
6. To test if the compressor is pumping properly, the compressor current draw must be compared to
published compressor performance curves using the operating pressures and voltage of the
system. If the measured average current deviates more than ±15% from published values, a faulty
compressor may be indicated. A current imbalance exceeding 15% of the average on the three
phases should be investigated further.
7. Before replacing or returning a compressor: Be certain that the compressor is actually
defective. At a minimum, recheck a compressor returned from the field in the shop or depot for
Hipot, winding resistance and ability to start before returning. More than one-third of
compressors returned for warranty analysis are determined to have nothing wrong. They were
misdiagnosed in the field as being defective. Replacing working compressors unnecessarily costs
everyone.

6.4.9

Compressor Replacement
Infrequently a fault in the motor insulation may result in a motor burn, but burnouts rarely occur in
a properly installed system. Of those that do, most are the effects of mechanical or lubrication failures, resulting in the burnout as a secondary consequence.
If problems that can cause compressor failures are detected and corrected early, a large percentage
can be prevented. Periodic maintenance inspections by alert service personnel on the lookout for
abnormal operation can be a major factor in reducing maintenance costs. It is easier and far less
costly to take the steps necessary to ensure proper system operation than it is to allow a compressor
to fail and require replacement.
When troubleshooting a compressor, check all electrical components for proper operation.
1. Check all fuses and circuit breakers.
2. Check Hi-Lo Pressure switch operation.
3. If a compressor failure has occurred, determine whether it is an electrical or mechanical failure.

Mechanical Failure
A mechanical compressor failure will be not be indicated by a burned odor. The motor will attempt to
run. If you have determined that a mechanical failure has occurred, the compressor must be replaced.
If a burnout does occur, correct the problem that caused the burnout and clean the system. It is
important to note that successive burnouts of the same system are usually caused by improper cleaning.

51

Component Operation and Maintenance

Electrical Failure
An electrical failure will be indicated by a distinct pungent odor. If a severe burnout has occurred, the
oil will be black and acidic.
In the event that there is an electrical failure and a complete burnout of the refrigeration compressor
motor, the proper procedures must be performed in order to clean the system to remove any acids that
would cause a future failure.

!

CAUTION

Damage to a replacement compressor caused by improper system cleaning constitutes
abuse under the terms of the warranty, and the WARRANTY WILL BE VOID.

There are two kits that can be used with a complete compressor burnout - Sporlan System Cleaner
and Alco Dri-Kleener. Follow the manufacturer's procedure.

!

CAUTION

Avoid touching or contacting the gas and oils with exposed skin. Severe burns will
result. Use long rubber gloves in handling contaminated parts.

Compressor Replacement Procedure
Replacement compressors are available from your Liebert supplier. They will be shipped in a reusable
crate to the job site as required by the service contractor.
Upon shipping a replacement compressor, the service contractor will be billed in full for the compressor until the replacement has been returned to the factory.
The compressor should be returned in the same container used for shipping to the job. The possible
damage causes or conditions that were found should be recorded by marking the compressor return
tag.
1. Disconnect power.
2. Attach suction and discharge gauges to access fittings.
3. Recover refrigerant using standard recovery procedures and equipment. Use a filter-drier when
charging the system with recovered refrigerant.

!

CAUTION

Do not loosen any refrigeration or electrical connections before relieving pressure.
NOTE
Release of refrigerant to the atmosphere is harmful to the environment and is unlawful.
Refrigerant must be recycled or discarded in accordance with federal, state, and local
regulations.

4. Front seat service valves to isolate the compressor. Reclaim charge from compressor.
5. Remove service valves, pressure switch capillaries, and disconnect all electrical connections.
6. Remove failed compressor.

!

7.
8.
9.
10.

CAUTION

A scroll compressor must rotate in the proper direction. Record compressor motor
connections when removing failed compressor. Wire the replacement compressor motor
the same way to maintain proper rotation direction.
Install replacement compressor and make all connections.
Pressurize and leak test the system at approximately 150 PSIG (1034 kPa) pressure.
Follow manufacturer's instructions for clean-out kits.
Follow charging instructions as stated in the installation manual, Liebert part number SL-11925.

52

Component Operation and Maintenance

6.5

Humidifier

6.5.1

Infrared Humidifier
During normal humidifier operation, deposits of mineral solids will collect in the humidifier pan. This
should be cleaned out periodically to ensure efficient operation. Each water supply has different characteristics, so the time interval between cleanings must be determined locally. A monthly check (and
cleaning if necessary) is recommended.

Removing the Pan
To remove humidifier pan, first open disconnect switch and open front panel. Allow time for pan and
water to cool. Unlatch front retainer clip (or remove screw from bracket on some units). Pull pan forward. Remove stand pipe to allow pan to drain. Disconnect drain line. Pull pan forward to remove it.

!

CAUTION

Before removing pan, be sure power to unit is disconnected and water in the humidifier pan
is no hotter than lukewarm.

Cleaning the Pan
An autoflush system can greatly increase the time between cleanings but does not eliminate the need
for periodic checks and maintenance.
Scale on the side and bottom can be loosened with a stiff brush. Flush with water and replace pan in
humidifier.

Changing Humidifier Lamps
1.
2.
3.
4.

Open disconnect switch.
Open front panel.
Remove screws securing line voltage compartment cover, then remove the cover.
In line voltage compartment, disconnect one end of the purple jumpers, then locate the burned out
bulb with a continuity meter.
5. Remove humidifier pan. Refer to Removing the Pan on page 53.
6. Remove lamp brackets (2) under lamps.

Figure 12 Infrared humidifier lamps
Humidifier Lamps

7. Loosen two screws securing bulb wires to junction block.
8. Pull bulb straight down.
9. Replace bulb. Wrap wires once loosely around bulb. This will support the bulb and also allow for
thermal expansion. Make sure lamp wires are secure in the junction block.

!

CAUTION

Do not touch the quartz lamps with your bare hands. Oily deposits such as fingerprints will
severely shorten bulb life. Use clean cotton gloves at all times.

10. Reverse Steps 1 through 6 to reassemble.

53

Component Operation and Maintenance

Autoflush Infrared Humidifier Cleaning System
NOTE
To operate properly, the Autoflush Humidifier requires a water source that can deliver at
least 1 gpm (0.063 l/s) with a minimum pressure of 20 psig (138 kPa).
The autoflush system will periodically flush the humidifier pan with water to prevent the buildup of
water minerals due to saturation. Because water conditions vary, the amount of water flushing
through the system may be programmed to match local needs.
Water amounts between 110% and 500% of the amount needed for humidification may be selected.
Operation of the flushing system is then automatic and no further adjustments need to be made.

Autoflush Operation
The operation of the autoflush is divided into four steps, beginning with a call for humidification.
1. If the humidifier has not been activated for over 30 hours, the autoflush will flow water into the
pan for about 30 seconds. This will provide a minimum amount of water in the pan and prevent
heat damage to the humidifier pan. Humidifier lamps are OFF.
2. If the humidifier has been activated within the last 30 hours, Step 1 is bypassed. The autoflush
will flow water into the pan for about 4 minutes. The humidifier lamps are on and the humidifier
is operational during this period. When the pan is filled (the fill cycle has timed out), the water
make-up valve is closed.
3. The water make-up valve remains OFF and the humidifier lamps are ON for a maximum of
9-1/2 minutes.
4. After the 9-1/2 minute delay, the autoflush adds water to the pan to replenish the water used in
humidification and flush the pan of mineral solids. This amount of water is adjustable from 110%
to 500% in increments of 10%. At the end of this cycle, the make-up valve is closed. Steps 3 and 4
repeat as long as humidification is required.

Autoflush Controls
Use the LCD display, menu, and keys on the front control panel to program the autoflush controls.

6.5.2

Steam Generating Humidifier
Steam generating humidifiers are designed to operate in voltage ranges from 200 to 575 volts and
generate 11 pounds (5 kg) of steam per hour. These humidifiers operate efficiently over a wide range
of water quality conditions and automatically adjust to changes in the conductivity of water. The
humidifiers drain and refill to maintain an amperage setpoint and alert the operator when the
humidifier canister needs to be replaced. The humidifier is in the lower section of upflow units; it is in
the middle section of downflow units.

Figure 13 Steam generating humidifier

54

Component Operation and Maintenance

Operation
1. During start-up, when the humidity control calls for humidification, the fill valve opens and
allows water to enter the canister. When the water level reaches the electrodes, current flows and
the water begins to warm. The canister fills until the amperage reaches the setpoint and the fill
valve closes. As the water warms, its conductivity increases and the current flow, in turn, rises. If
the amperage reaches 115% of the normal operating amperage, the drain valve opens and flushes
some of the water out of the canister. This reduces electrode contact with the water and lowers
the current flow to the amperage setpoint. Boiling soon commences, and the canister operates
normally.
2. If the conductivity of the water is low, the canister fills and the water level reaches the canister
full electrode before the amperage setpoint is reached. The humidifier stops filling to prevent
overflow. Boiling should commence in time. As water is boiled off, the mineral concentration in
the canister increases and current flow also increases. The canister eventually reaches full output
and goes to normal operation. No drain is permitted until then.
3. When full output is reached the circuit board starts a time cycle which is factory set at 60 seconds.
During this repeating time cycle, the fill valve will open periodically to replenish the water being
boiled off and maintain a “steady state” output at the set point. The amperage variance will
depend on the conductivity of the water.
4. After a period of time, the mineral concentration in the canister becomes too high. When this
occurs, the water boils too quickly. As the water quickly boils off and less of the electrode is
exposed, the current flow decreases. When the current crosses the low threshold point (factory set
at 90%) before the end of the time cycle, the drain valve opens, draining the mineral laden water
out and replacing it with fresh water. This lowers the mineral concentration and returns the
canister to “steady state” operation and prolongs canister life. The frequency of drains depends on
water conductivity.
5. Over a period of time, the electrode surface will become coated with a layer of insulating material,
which causes a drop in current flow. As this happens, the water level in the canister will slowly
rise exposing new electrode surface to the water to maintain normal output. Eventually, the
steady state water level will reach the canister full electrode and indicate so by activating the
canister full alarm. At this point, all of electrode surface has been used up and the canister should
be replaced.
6. After the entire electrode surface has been coated, the output will slowly begin to fall off. This
usually occurs in the last several hours of electrode life and should allow enough time to schedule
maintenance. During these last hours, the mineral concentration can increase. If the mineral
concentration is too high, arcing can occur. If the electrodes start to arc, turn off the humidifier
immediately and replace the canister with the identical part.

Controls
The humidifier RUN/DRAIN switch is located at the upper right of the humidifier assembly. This
switch should be in the RUN position when the humidifier is in normal operation, and in the DRAIN
position when a manual drain sequence is required. The electronic control board for the humidifier is
located on the right side of the humidifier assembly. When the main unit is energized, power is available to the humidifier circuits.

55

Component Operation and Maintenance

Replacing the Canister
Over a period of operation, the humidifier electrodes become coated with mineral solids. This coating
insulates the electrodes and decreases the current flow. To maintain humidifier capacity, the water
level slowly rises to expose fresh electrode. Eventually, the entire electrode becomes coated and the
water level reaches the top. At this point, the canister full alarm is activated and the output begins to
fall. When this happens, it is necessary to replace the full canister.
To replace the canister:
1. Turn off the humidifier by lowering the humidity setpoint below the ambient humidity level.
Record the original setpoint.
2. Place the RUN/DRAIN switch in the DRAIN position to drain the water from the canister.
3. Return the RUN/DRAIN switch to the RUN position after the canister has drained.

!

WARNING

To avoid a shock hazard, all power to the unit must be disconnected before proceeding with
the canister replacement procedure.

4. Turn OFF the power at the main unit.
5. Remove the cover from the humidifier cabinet.

!

CAUTION

The canister and steam hose may be hot! Allow time for the humidifier to cool before
replacing parts.

6. Locate the power wires to the steam canister. They are connected to the canister with 1/4" quick
connects. Make note of the wiring configuration before removing any wires. Refer to the schematic
on the unit. Slide the rubber boot back to expose the connections. Remove the three power wires
and the two canister full wires. Do not loosen the screws that secure the electrodes.
7. Loosen the steam outlet hose clamp and slide the steam hose away from the canister top fitting.
8. The canister is now ready to be removed. Pull the canister straight up and out of the cabinet
toward you.
9. Replace the canister with the part indicated in Table 20.
Table 20

Humidifier canister part numbers

Part
Number

Voltage

Capacity
lbs/hr (kg/hr)

136798P1

200-460*

11 (5)

136798P2

380-575

11 (5)

* Can operate on 575 V unit with transformer

10. Replace the canister by reversing the above procedure. Make special note of the following:
NOTE
When replacing the canister:
1. Make sure the two “O” rings are lubricated and properly seated on the bottom neck.
2. Always check the fill and drain solenoids for proper operation.
NOTE
When replacing the wiring, connect the red wire from terminal #1 on the interface to the red top
terminal on the canister. It is in the middle of a group of three terminals. The black wire from
terminal #2 on the interface connects to the power terminal farthest from the red terminal/
wire. The power wire to this terminal is routed through the current sensing coil.

56

Component Operation and Maintenance

Figure 14 Canister replacement

Circuit Board Adjustments

!

WARNING

Circuit board adjustment should be performed by qualified personnel only. Hazardous
voltages are present in the equipment throughout the procedure. Use extreme caution. If
desired, power may be disconnected prior to the procedure.

Humidifier operation is governed by the humidifier control board. This board is located on the right
side of the humidifier compartment. There are three potentiometers mounted on the board. These
pots can be used to adjust for extreme water conductivity conditions and capacity.
The “%” pot controls the amperage at which the drain will energize. The pot is clearly marked in percentages. This adjustment is factory set at 90%, which indicates that the unit will drain when the
amperage falls off to 90% of the capacity setpoint. Raising the value increases the frequency of drain
cycles. Lowering the value decreases the frequency of drain cycles. The frequency should be increased
for highly conductive water and decreased for less conductive water. If adjustment is necessary, and a
change of three to four percent in either direction does not permit normal operation of the unit, consult your Liebert supplier.
The pot marked “SEC” controls the duration of the drain cycle. The pot is clearly marked in seconds.
This adjustment is factory set at 60 seconds and should not be readjusted without consulting your
Liebert supplier.
The pot marked “CAP ADJ” is factory set at 100%. The maximum capacity is determined by a fixed
resistor (R4) which is factory selected based on unit voltage.

Drain Tempering Feature
All units are equipped with a drain tempering feature which mixes cold fill water with hot drain
water to protect drain piping. This feature can lower drain water temperature to as low as 140°F
(60°C), depending on water pressure. To deactivate this feature, remove the diode from socket CR18
on the circuit board (lower left, above LED).

57

Troubleshooting

7.0

TROUBLESHOOTING
Use this section to assist in troubleshooting your unit. Also refer to 5.0 - Alarm Descriptions. Suggestions are grouped by product function for convenience.

Table 21

!

WARNING

!

CAUTION

Only qualified personnel should perform service on these units. Lethal voltage is present in
some circuits. Use caution when troubleshooting with power on. Disconnect and lock out
power before replacing components. Use caution and standard procedures when working with
pressurized pipes and tubes.

When using jumpers for troubleshooting, always remove jumpers when maintenance is
complete. Jumpers left connected could override controls and cause equipment damage.
Blower troubleshooting

Symptom
Blower will not start

Table 22

Possible Cause

Check or Remedy

No main power

Check L1, L2 and L3 for rated voltage.

Blown fuse or tripped circuit breaker (CB)

Check fuses or CBs to main fan.

Overloads tripped

Push reset button on main fan overload. Check amp
draw.

No output voltage from transformer

Check for 24 VAC between P24-2 and P24-1. If no
voltage, check primary voltage.

Control fuse blown or circuit breaker tripped

Check for 24 VAC between P4-4 and E1. If no voltage,
check for short. Replace fuse or reset circuit breaker.

Chilled water troubleshooting

Symptom
Chilled water or hot
water/steam valve
not opening
Modulating Motors

Actuator Motors

Possible Cause

Check or Remedy

Motor operates but valve won’t open

Check linkage for adjustment and be sure that it is
tight on the valve.

No 24 VAC power to motor

Check linkage for adjustment and be sure that it is
tight on the valve.

No signal from control

Check DC voltage on printed circuit board in motor.
Terminal No. 1 is grounded and No. 3 is positive. DC
voltage should vary from 0.8 to 2.0 VDC or above as
temperature control is varied below room temperature
on cooling valve or above room temperature on
heating valve.

Motor not working

Remove wires on terminal No. 1 and No. 3 from the
motor (do not short). With 24 VAC power from TR to
TR jumper terminal 1 and 2 on motor to drive open.
Remove jumper to drive closed, if motor fails to work,
replace it.

No 24 VAC power to motor

Check for 24 VAC between P22-3 and P22-5 (open),
or P22-1 and P22-5 (closed).

58

Troubleshooting

Table 23

Compressor and refrigeration system troubleshooting
Symptom

Possible Cause

Check or Remedy

Power off

Check main switch, fuses or CBs and
wiring

Current overload open

Re-set units with overload option
manually. Allow compressor to cool for
internal overloads to reset.

Loose electrical connections

Tighten connections

Compressor motor burned out

Check and replace compressor if
defective.

No call for cooling

Check monitor status.

Solenoid valve not energizing

Hold screwdriver over solenoid and check
for magnetic field. This indicates solenoid
is energized.

Low pressure switch not making contact

Check gas pressure - manually energize
low pressure switch.

Compressor will not operate,
contact not pulling in

High pressure switch open

Reset switch. Refer to other refrigeration
troubleshooting suggestions.

Compressor contactor pulled in but
compressor will not operate

Blown fuse or tripped CB

Check for line voltage after fuses or CBs,
and after contactors.

Low pressure switch not closing

Check for low gas pressure. Compressor
is running on Positive Start Kit (air cooled
systems only)

Compressor will not start

Compressor will not operate,
contactor not pulling in

Compressor runs for three minutes
then stops; contactor drops out.

High discharge pressure

Low discharge pressure

Low suction pressure

Liquid line solenoid valve not opening

Check magnetic field to see if energized.

Dirty condenser or drycooler fins

Clean coil.

Condenser equipment not operating

Check operation.

High refrigerant charge

Check refrigerant charge.

Hot gas bypass valve adjusted
improperly

Adjust properly.

Water regulating valve adjusted
improperly

Adjust properly.

Excessive fluid flow through condenser

Adjust fluid regulating valve

Suction service valve partially closed

Open the valve.

Faulty head pressure control valve or
condenser fan speed control

Replace if defective.

Compressor rotation in reverse direction

Check for proper power phase wiring to
unit and to compressor motor.

Insufficient refrigerant in system

Check for leaks, repair, and add
refrigerant for air cooled. Evacuate and
recharge for water/glycol unit.

Dirty air filters

Change filters.

Plugged filter-drier

Replace filter.

Improper superheat adjustment

Reset expansion valve for 10-15°F
(6-8°C)

Defective expansion valve sensing
element

Replace element

Poor air distribution

Check duct work for closed dampers.
Check for under-floor restrictions at or
near the unit.

Low condensing pressure

Check head pressure control device.

Slipping belts

Inspect and adjust

59

Troubleshooting

Table 23

Compressor and refrigeration system troubleshooting (continued)
Symptom

Possible Cause

Check or Remedy

Defective or improperly set expansion
valve

Increase superheat or replace valve

Evaporator fan motor or belt

Correct problem or replace fan motor and/
or belts.

Low condensing pressure

Check head pressure control device

Slipping belts

Inspect and adjust

Compressor rotation in reverse
direction.

Check for proper power phase wiring to
unit and to compressor motor.

Leaking liquid line solenoid valve or dirt
in valve

Replace valve if clean; clean out valve if
dirty.

Compressor noisy

Loose compressor or piping support

Tighten clamps.

Pipe rattle

Loose pipe connections

Check pipe connections

Compression ratio too high

Check setting of high and low pressure
switches. Check condenser -- is it
plugged? Check that all evaporator and
condenser fans are operating properly.

Low-pressure switch erratic in operation

Check tubing to switch to see if clogged or
crimped. Check for proper switch
operation.

Insufficient refrigerant in system

Check for leaks, fix, and add refrigerant on
air cooled unit. Evacuate and recharge
water/glycol unit.

Suction service valve closed

Open valve.

Insufficient fluid flowing through
condenser or clogged condenser, or
dirty air cooled condenser coils

Adjust fluid regulating valve to condenser.
Flush the condenser.

Discharge service valve not fully open

Open valve

Faulty low pressure switch

Repair or replace.

Dirt or restriction in tubing to pressure
stat

Check and clean tubing.

Defective liquid line solenoid valve

Check valve and solenoid operator;
replace if necessary.

Plugged filter-drier

Replace filter.

High discharge pressure

Check for loss of condenser water or
blocked condenser fan or coil.

Defective overload relay

Replace.

High suction temperature

Reduce suction temperature by expansion
valve adjustment or provide
desuperheating.

Loose power or control circuit wiring
connection

Check all power and control circuit
connections.

Defective motor

Check for motor ground or short. Replace
compressor, if either condition is found.

Low line voltage

Check line voltage and determine location
of voltage drop.

Compressor motor defective

Check for motor winding short or ground.

Single phasing

Check voltage across all 3 legs at
contactor. Correct source problem.

Check control panel for welded
contactor contacts or welded overload
contacts

Replace defective components

Flooding

Low compressor capacity or
inability to pull down system

Compressor running hot

Compressor cycles intermittently

Compressor cycles continually

Compressor motor protectors
tripping or cycling

Compressor cycles on locked rotor

Motor burnout

60

Troubleshooting

Table 24

Dehumidification troubleshooting
Symptom

No dehumidification

Table 25

Possible Cause

Check or Remedy

Control not calling for
dehumidification

Check monitor status.

Compressor contactor not pulling in

See 6.4.8 - Compressor Functional
Check and Table 23.

Compressor won't run; fuse blown or
CB tripped

See 6.4.8 - Compressor Functional
Check and Table 23. Check fuses or
CBs and contacts. Check line voltage

Glycol pump troubleshooting
Symptom

Possible Cause

Check or Remedy

Suddenly stops pumping

Clogged strainer or impeller

Clean out debris.

Suddenly slow pumping

Clogged impeller, diffuser, or line

Clean out debris and use strainer.

Excessive leakage around the pump
shaft while operating

Worn seal or packing

Replace seal or packing.

Worn impeller or seal

Replace with new impeller or seal.

Suction lift too high

Relocate pump closer to supply.

Motor not up to speed; low voltage

Larger lead wires may be required.
Check for proper line voltage (±10%).

Worn bearings

Replace pump

Worn motor bearings

Replace pump

Low discharge head

Throttle discharge-improve suction
conditions.

Debris lodged in impeller

Remove cover and clean out.

Cavitating pumps

Adjust system pressures.

Performance poor

Noisy operation

Table 26

Infrared humidifier troubleshooting
Symptom

No humidification

Possible Cause
Humidifier pan not filling

Check or Remedy
Check water supply.
Check fill valve operation
Check drain stand pipe adjustment
Check for clogged waterline

Control not calling for humidity

Check monitor status

Humidity contact not pulling in

Check visually. If contact is made,
check line voltage after contactor and
fuses or CBs.
Check for open humidifier safety stat.
Jumper between terminals P35-6 and
P35-15. If contactor pulls in, replace
safety. Remove jumper.

Humidifier bulb burned out

61

Replace bulb. Loosen lead on old
bulb. Trim excess lead length on new
bulb to avoid shorts.

Troubleshooting

Table 27

Steam generating humidifier troubleshooting
Symptom

Possible Cause

Check or Remedy
Check drain valve to ensure that it drains freely. Check and
replace if defective.

Foaming

Check water supply. If commercially softened, reconnect to
raw water supply. If connected to hot water reconnect to
cold water.

Main 24 VAC fuse or circuit
breaker trips

Shorts or loose connections

Check the wiring connections of the 24 VAC circuit.

Faulty circuit board

Replace the circuit board.

Main fuses blow
approximately 15 seconds
after unit is activated

Faulty solenoid

Check for magnetic field at coil.

Conductivity too high

Check amp draw of humidifier on startup. If it exceeds rated
amps, increase setting of the % pot on the circuit board

Mineral deposits obstruct
drain valve

Check drain valve for obstructions and clean if necessary.

Faulty solenoid

Check for magnetic field at coil.

Faulty circuit board

Replace circuit board.

False canister full indication

Main fuses blow when
drain valve is activated.

Verify that RUN/DRAIN switch is in the RUN position.
Unit ON, humidifier will not
operate

Contactor pulled in, but no
water enters canister

Humidifier not receiving power

Make sure molex connector is securely plugged into circuit
board and that no wires are loose.

No water available to unit

Check external shut-off valves.

Clogged fill line strainer

Clean or replace fill line strainer.

Wiring breaks or loose
connections

Check for faulty wiring and loose connections.

Faulty circuit board

Replace circuit board.

Foaming

Check drain valve and water supply.
Check connection on component plate in humidifier cabinet.
Terminal #1 on the square block interface device must be
connected to L2 of the power terminal block. L2 must also
be connected to the electrode closest to the steam outlet
port.

Canister interface connections
incorrect

Verify that the red wire from terminal #2 on the interface
connects to the red top terminal on the canister. This is the
one farthest from the steam outlet port and is the high water
sensor probe.

Water enters canister, but
canister full circuit activates
at a low water level

Canister fills but overflows

Check fuses or CBs and replace or reset if necessary.

Full isolation has broken down

Remove red canister full wire from canister. If normal
operation resumes, canister must be replaced. Remove the
wire from terminal #3 on the interface. If normal operation
resumes, canister full interface must be replaced.

Drain assembly not operating
freely

Check and replace coil or valve if necessary.

Faulty circuit board

Replace circuit board

Canister full circuit does not
activate

Check wiring of canister full interface. Replace circuit board.

62

Troubleshooting

Table 27

Steam generating humidifier troubleshooting (continued)
Symptom

Possible Cause

Check or Remedy

Drain valve clogged or
defective

Verify that drain valve operates freely when activated. Clean
valve and replace coil or valve if defective. Flush canister
several times and replace if arcing persists.

Improper water supply

If water is commercially softened, reconnect humidifier to
raw water supply, drain canister, and restart If connected to
hot supply, reconnect to cold water.

Insufficient drain rate

Increase drain rate by adjusting % pot on circuit board
above the preset 70% to roughly 80%.

Excessive iron content in
water

Analyze iron content of water. If it exceeds 0.1 mg./l, install
a filter to remove iron from water supply.

On cold start-up, canister
fills, high water alarm
activates and humidifier
fails to reach full amperage

Conductivity of water too low

Drain canister and add one Alka-Seltzer tablet to canister.
Refill. Turn the % pot to roughly 60%. Restart humidifier. If
amperage rises rapidly, it may be necessary to dilute the
water to prevent blown fuses. If it rises too slowly, add
another Alka-Seltzer tablet.

On cold start-up, canister
fills, high water alarm
activates and humidifier
fails to reach full amperage

Fill solenoid not closing tightly

If humidifier returns to canister full condition, verity that the
fill solenoid closes tightly.

Excessive arcing in the
canister

Table 28

Reheat troubleshooting

Symptom
Reheat will not operate;
contactor not pulling in
Reheat not operating;
contactor pulling in

Possible Cause

Check or Remedy

Control not calling for heat

Check monitor status.

Reheat safety stat open

Jumper between terminals P34-1 and P34-2. If reheat operates,
safety is open. Remove jumper. Replace safety.

Heater burned out

Turn off power and check heater continuity with Ohm meter.

NOTE:
Reheat element sheaths and fins are manufactured with stainless steel. Regular inspections
are necessary to assure proper cleanliness of the reheating element. Should inspection reveal
corrosion particles on the reheating element or adjoining surfaces (including ducts and
plenums), appropriate cleaning should be performed. Periodic reheating element replacement
may be required to meet specific application requirements.

63

Monthly Maintenance Inspection Checklist

8.0

MONTHLY MAINTENANCE INSPECTION CHECKLIST

Date:_______________________________________

Prepared by:_________________________________

Model #:_____________________________________

Serial #:____________________________________

Filters
___ 1. Restricted air flow

Steam Generating Humidifier
___ 1. Check canister for deposits

___ 2. Check filter switch

___ 2. Check condition of steam hoses

___ 3. Wipe section clean

___ 3. Check water make-up valve for
leaks

Blower Section
___ 1. Impellers free of debris and move freely

Infrared Humidifier
___ 1. Check pan drain for clogs

___ 2. Check belt tension and condition

___ 2. Check humidifier lamps

___ 3. Bearings in good condition

___ 3. Check pan for mineral deposits

Compressor
___ 1. Check oil leaks

Refrigeration Cycle/Section
___ 1. Check refrigerant lines

___ 2. Check for leaks

___ 2. Check for moisture (sight glass)

Air Cooled Condenser (if applicable)

___ 3. Check suction pressure

___ 1. Condenser coil clean

___ 4. Check head pressure

___ 2. Motor mounts tight

___ 5. Check discharge pressure

___ 3. Bearings in good condition

___ 6. Check hot gas bypass valve

___ 4. Refrigerant lines properly
supported

___ 7. Check thermostatic exp. valve

Reheat
___ 1. Check reheat element operation

Air Distribution Section
___ 1. Restriction in grille free area

___ 2. Inspect elements for cleanliness

Refrigerant Charge
___ 1. Check refrigerant level

Notes

Signature
Make photocopies of this form for your records

64

Semiannual Maintenance Inspection Checklist

9.0

SEMIANNUAL MAINTENANCE INSPECTION CHECKLIST

Date:________________________________________

Prepared by:_________________________________

Model #:_____________________________________

Serial #:_____________________________________

Filters

Steam Generating Humidifier

___ 1. Restricted air flow
___ 2. Check filter switch
___ 3. Wipe section clean

___ 1.
___ 2.
___ 3.
___ 4.

Blower Section
___ 1.
___ 2.
___ 3.
___ 4.

Impellers free of debris and move freely
Check belt tension and condition
Bearings in good condition
Inspect & tighten electrical connections

Compressor
___ 1. Check oil leaks
___ 2. Check for leaks
___ 3. Inspect & tighten electrical connections

Air Cooled Condenser (if applicable)
___ 1.
___ 2.
___ 3.
___ 4.
___ 5.

Condenser coil clean
Motor mounts tight
Bearings in good condition
Refrigerant lines properly supported
Inspect & tighten electrical connections

Check canister for deposits
Check condition of steam hoses
Check water make-up valve for leaks
Inspect & tighten electrical connections

Infrared Humidifier
___ 1.
___ 2.
___ 3.
___ 4.

Check pan drain for clogs
Check humidifier lamps
Check pan for mineral deposits
Inspect & tighten electrical connections

Refrigeration Cycle/Section
___ 1.
___ 2.
___ 3.
___ 4.
___ 5.
___ 6.
___ 7.

Check refrigerant lines
Check for moisture (sight glass)
Check suction pressure
Check head pressure
Check discharge pressure
Check hot gas bypass valve
Check thermostatic exp. valve

Air Distribution Section

Water/Glycol Condenser (if applicable)

___ 1. Restriction in grille free area

___ 1.
___ 2.
___ 3.
___ 4.

Refrigerant Charge

Copper tube clean
Water regulating valves function
Glycol solution
Check for water/glycol leaks

Glycol Pump
___ 1. Glycol leaks
___ 2. Pump operation
___ 3. Inspect & tighten electrical connections

___ 1. Check refrigerant level

Electrical Panel
___ 1.
___ 2.
___ 3.
___ 4.

Check fuses
Inspect & tighten electrical connections
Check operation sequence
Check contactor operation

Reheat
___ 1. Check reheat element operation
___ 2. Inspect elements for cleanliness
___ 3. Inspect & tighten electrical connections

Notes

Signature
Make photocopies of this form for your records

65

Semiannual Maintenance Inspection Checklist

66

Ensuring The High Availability
0f Mission-Critical Data And Applications.

Emerson Network Power, the global leader in enabling business-critical
continuity, ensures network resiliency and adaptability through
a family of technologies—including Liebert power and cooling
technologies—that protect and support business-critical systems.
Liebert solutions employ an adaptive architecture that responds
to changes in criticality, density and capacity. Enterprises benefit
from greater IT system availability, operational flexibility and
reduced capital equipment and operating costs.

Technical Support / Service
Web Site
www.liebert.com
Monitoring
800-222-5877
monitoring@emersonnetworkpower.com
Outside the US: 614-841-6755
Single-Phase UPS
800-222-5877
upstech@emersonnetworkpower.com
Outside the US: 614-841-6755
Three-Phase UPS
800-543-2378
powertech@emersonnetworkpower.com
Environmental Systems
800-543-2778
Outside the United States
614-888-0246

Locations
United States
1050 Dearborn Drive
P.O. Box 29186
Columbus, OH 43229
Europe
Via Leonardo Da Vinci 8
Zona Industriale Tognana
35028 Piove Di Sacco (PD) Italy
+39 049 9719 111
Fax: +39 049 5841 257
Asia
7/F, Dah Sing Financial Centre
108 Gloucester Road, Wanchai
Hong Kong
852 2572220
Fax: 852 28029250

While every precaution has been taken to ensure the accuracy
and completeness of this literature, Liebert Corporation assumes no
responsibility and disclaims all liability for damages resulting from use of
this information or for any errors or omissions.
© 2006 Liebert Corporation
All rights reserved throughout the world. Specifications subject to change
without notice.
® Liebert and the Liebert logo are registered trademarks of Liebert
Corporation. All names referred to are trademarks
or registered trademarks of their respective owners.

SL-11935 _REV1_08-06

Emerson Network Power.
The global leader in enabling Business-Critical Continuity™.
AC Power Systems
Embedded Computing
Embedded Power
Connectivity
DC Power Systems

Integrated Cabinet Solutions

EmersonNetworkPower.com
Outside Plant
Services
Power Switching & Control
Site Monitoring
Precision Cooling

Surge Protection

Business-Critical Continuity, Emerson Network Power and the Emerson Network Power logo are trademarks and service marks of Emerson Electric Co.
©2006 Emerson Electric Co.



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