Honeywell Aquastatic L7224 Users Manual 69 1957 1 Series Oil Electronic Aquastat Controller

L7224 to the manual 173d3f9c-bf00-496a-b296-a0e9e7891f08

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69-1957-1.fm Page 1 Tuesday, June 20, 2006 11:06 AM

L7224 Series
Oil Electronic
Aquastat® Controller
TECHNICIAN’S QUICK REFERENCE GUIDE
The following service procedure provides a quick overview for
L7224 Series Controllers. For more information, refer to form
69-1384.
On the L7224U the High Limit, High Limit Differential, Low Limit,
and Low Limit Differential can be adjusted to the settings
recommended by the boiler OEM.

Adjusting Settings
To discourage unauthorized changing of Aquastat® settings, a
procedure to enter the adjustment mode is required. To enter the
adjustment mode, press the UP, DOWN, and I buttons
simultaneously for three seconds. Press the I button until the
feature requiring adjustment is displayed:
• HL—High Limit.
• LL—Low Limit.
• Ldf—Low Limit differential.
• F - C—°F or °C.
Then press the UP and/or DOWN buttons to move the set point to
the desired value. After 60 seconds without any button inputs, the
control will automatically return to the READ mode.
To use the L7224U in a cold start boiler application, disable the
Low Limit function by pressing the UP arrow button, DOWN arrow
button and I buttons simultaneously for three seconds. Then push
the I button until LL is displayed. Then press the down arrow
button until OFF is displayed.

Display
In the RUN mode, the Aquastat® will flash “bt” (boiler temp)
followed by the temperature (i.e., 220), followed by °F or °C.
To read boiler settings, press the I key to read the parameter of
interest. For example, press I (HL) High Limit is displayed,
followed by a three-digit number, i.e., 220, followed by °F or °C.

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69-1957-1.fm Page 2 Tuesday, June 20, 2006 11:06 AM

L7224 SERIES
Pressing the I button again will display the LL (Low Limit) followed
by a three-digit number and the corresponding degree designator.
See the table below for an explanation of display readout.
After approximately 60 seconds without any key presses, the
display will enter a dim display mode. To return to the bright
display mode, simply press and release any key.

Text

Description

bt

Boiler Temperature

HL

High Limit

LL

Low Limit

Hdf

High Limit Differential

Ldf

Low Limit Differential

tt

Local Thermostat Status

tte

Enviracom Thermostat Status

brn

Burner Status

cir

Circulator Status

Zc

Zone Control

Zr

Zone Request

err

Error Code

f
c

Display
Shows

Degrees Fahrenheit
Degrees Celsius
M22149

Table 1. LED Error Codes
Error Code
Err1
Err2
Err3
Err4
Err5
Err6
Err7
Err8

69-1957—1

Cause/Action
Sensor fault; check sensor.
ECOM fault; check EnviraCOM. wiring.
Hardware fault; replace control.
B1 fault; check B1 wiring/voltage.
Low Line; Check L1-L2, 110 Vac.
Fuse; Check ECOM wires, Replace fuse.
EEPROM, HL, LL, Hdf, Ldf, Reset to default values.
Repeated B1 fault (voltage present at B1 when
output is turned off); check B1 wiring/voltage.

2

69-1957-1.fm Page 3 Tuesday, June 20, 2006 11:06 AM

L7224 SERIES
Table 2. L7224 Controller Operating Sequence
Action
Thermostat
calls for heat.

System Response
Circulator starts when water temperature is
above Low Limit setting (if applicable). Boiler
temperature is checked. Burner starts when
water temperature is below High Limit setting.
Boiler exceeds Burner is turned off. Burner restarts when the
the High Limit. water temperature drops below the High Limit
setting minus the differential.
Thermostat is Circulator and burner turn off.
satisfied.
Error conditions If an error condition is detected, all outputs
1-5.
except ZC are shut down. Burner is off. Control
continues to function and restarts when error is
corrected. During the error check sequence, the
system checks for drift in the sensor and
corrosion in the connections.
Error conditions If error condition 6 or 7 occurs, the control has
6-7.
reset the High Limit, Low Limit and Differential
Setting to a default setting and will continue to
run at those settings. Performance of the system
will be degraded.
Error condition If the error condition is detected, all outputs
8.
except ZC are shut down. Burner is off. Control
continues to function and restarts when all three
user keys have been pressed longer than 60
seconds.

Troubleshooting
When attempting to diagnose system performance, reference the
LED display to help identify specific areas not working properly.
The LED display will scroll “err”, followed by a digit (1-8). See
Table 1 for a description of the error and suggested actions. See
below for a troubleshooting guide.
Table 3. Troubleshooting Guidea.
System
Diagnostic
Condition Condition
Boiler is Display is OFF
cold,
house is Display is ON;
cold
TT-LED is OFF
Display is ON;
TT-LED is OFF

Check
Action
120 Vac system Turn system power on.
power.
24 Vac T-T
No 24V; replace
control
24V present;
Boiler starts, check
disconnect
wiring and thermostat
thermostat,
short T-T

a. Refer

to Fig. 5 for Display and LED locations.
. ZC LED ON indicates ZC terminal power is OFF.
c
. ZC LED OFF indicates ZC terminal power is ON.
b

3

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69-1957-1.fm Page 4 Tuesday, June 20, 2006 11:06 AM

Table 3. Troubleshooting Guidea.
System
Diagnostic
Condition Condition
Boiler is Display is ON;
cold,
TT-LED is ON
house is B1 LED is ON
cold
Display is ON;
TT-LED is ON
Boiler is Display is ON;
hot, house TT-LED is ON
is cold
C1 LED is ON

Display is ON;
TT-LED is ON
C1 LED is OFF;
ZC LED is ONb

Display is ON;
TT-LED is ON
ZC LED is
OFFc

Check
Action
120 Vac at B1- • If no, replace control.
B2
• If yes, check burner
and wiring
Refer to err on —
display
120 Vac at C1- • 120 Vac at C1-C2,
C2
check wiring to pump
• Wiring ok, is pump
running? If not,
replace the pump.
• If pump is running,
check for trapped air
or closed zone
valves.
Boiler below the
Low Limit
temperature,
wait for boiler to
go above Low
Limit
temperature.
Boiler above
• If no 120 Vac,
LL? If yes,
replace control.
check for 120 • If yes, check zone
Vac between ZC relays, circulators
and L2
and wiring.

a

. Refer to Fig. 5 for Display and LED locations.
. ZC LED ON indicates ZC terminal power is OFF.
c
. ZC LED OFF indicates ZC terminal power is ON.
b

Automation and Control Solutions
Honeywell International Inc.

Honeywell Limited-Honeywell Limitée

1985 Douglas Drive North

35 Dynamic Drive

Golden Valley, MN 55422

Toronto, Ontario M1V 4Z9

customer.honeywell.com

® U.S. Registered Trademark
© 2006 Honeywell International Inc.
69-1957—1 Rev. 06-06



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Title                           : 69-1957-1 L7224 Series Oil Electronic Aquastat Controller
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Description                     : Technician's Quick reference Guide
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Subject                         : Technician's Quick reference Guide
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