LENNOX Controls And HVAC Accessories Manual L0806363
User Manual: LENNOX LENNOX Controls and HVAC Accessories Manual LENNOX Controls and HVAC Accessories Owner's Manual, LENNOX Controls and HVAC Accessories installation guides
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ZENNOX
t,_2004 Lennox industries Inc,
Dallas, Texas, USA
INSTALLATION
INSTRUCTIONS
HEAT PUMP
KITS AND ACCESSORIES
_pu
Technical
blications
Lithe U.S.A.
FUELMASTER 21 ¢
CONTROL BOARD
502,755M
09/2004
Supersedes 05/2003
FOR FUELMASTER
21 ¢ (FM21)
CONTROL
BOARD
If the optional defrost thermostat probe, DTR1, is used,
the indoor blower will run continuously on high speed
Package 1 of 1 contains:
1 - FM21 board
during both first-stage and second-stage heating without
interruption.
1 - Mounting box with cover
1 - Bag assembly containing:
4 - #8 - 18 x 1/2" screws
1. Determine an appropriate indoor location close to
the furnace to install the FM21 control box. The box
may be installed on the furnace to facilitate wiring.
The FM21 FueIMaster 21 ° control board is designed for
IMPORTANT
use with a conventional gas or oil furnace in combination
with a heat pump.Optional kits for service light (SLC1)
and defrost thermostat probe (DTR1) are available. An
outdoor thermostat may be used with the FM21 when
low temperature heat pump lockout is desired.
.
NOTE - A time delay relay (54G5701) is required when
an outdoor thermostat is used.
When the outdoor temperature is below the outdoor thermostat setting, the time delay relay (DL10) will provide a
two-second delay before the compressor contactor is
energized. Refer to figure 3 for field wiring.
.
.
During a call for heat with the FM21, the heat pump will
provide first- stage heating. However, if first-stage operation does not satisfy the heating demand, secondstage heat is provided by the furnace as the secondary
source of heat. The FM21 automatically terminates heat
pump operation and starts the furnace.
The FM21 also controls the indoor blower speed. The indoor blower runs in high speed during first-stage heating
(provided by the heat pump). When there is a need for
second-stage heating, the FM21 stops the blower, allows the furnace heat exchanger to warm up, and then
operates the indoor blower on heating speed. In situations that require the blower to run continuously, the
blower speed will change automatically from heat pump
(high speed) to furnace (heating speed).
Page 1
Use the provided screws to secure the control box.
Refer to figure 1 for dimensions.
NOTE - Standard 18-gauge thermostat wire is recommended for all wiring.
Remove the FM21 control box cover and make the
thermostat connections to the FM21 board, Terminals for the thermostat connections are located on
the left side of the FM21 board,
Make furnace and heat pump connections to terminals on the FM21 board, These terminals are located on the right side of the FM21 board,
NOTE - If the furnace is equipped with a SureLighltb
ignition control board, a wire must be connected
from the heat pump Y1 terminal on the FM21 board
to the Y terminal on the furnace SureLight ignition
control board. This will ensure indoor blower operation on cooling speed during heat pump operation.
5.
Run wires through the electrical inlets as shown in
figure 2.
6. If outdoor thermostat (S26) is being used with FM21,
remove jumper JR2 that is located on the upper left
side of the FM21 board. The jumper may be stored
by placing it on one pin only. Wire the outdoor thermostat (S26) to the outdoor thermostat terminals on
the FM21 board. See figure 3 for wiring.
7. If usingoptionalDTRI-1defrostthermostatboard,
removejumperJR1whichis locatedat the upper
rightsideoftheFM21board.Jumpermaybestored
byplacingitononepinonly.InstallDTRI-1boardas
outlinedin the installation
instructionshippedwith
thekit,
LENNOX
8. If usingoptionalSLC1servicelightcontrol,install
andadjustas outlinedin theinstallation
instruction
shippedwiththekit,
Checkthe operationof the controlusingthe troubleshootingtablesandoperationdiagrams.
FM21 DIMENSIONS
_!--
1-7/8
(48)_"
2-5/8
(67)
MOUNTING
3/16
HOLES (4)
(5)
DTR1
DEFROST KIT
(OPTIONAL)
10-1/2
5-1/4
(133)
FM21
CONTROL
BOARD
(267)
SLCl
SERVICE
LIGHT KIT
(OPTIONAL)
2-5/8
(67)
FRONT VIEW
SIDE VIEW
Figure
Page 2
1
LENNOX
ToOptionalOutdoor
Thermostat(3wires)
FM21 WIRING
INLETS
To Optional DTRI-1
Probe (2 wires)
To Furnace (5 wires)
Wire used only
if furnace is
/ equipped with
SureLight ignition
control board
MOUNTING
HOLES (4) _
DTR1
DEFROST KIT
(OPTIONAL)
FM21
CONTROL
BOARD
SLCl SERVICE
LIGHT KIT
(OPTIONAL)
To Room
Thermostat (10
wires maximum)
FRONT VIEW
Figure
2
Page 3
To Heat Pump (8
wires maximum)
DISCHARGE
SB9
THERMOSTAT
PROBE
NOTE EXTERNAL 75VA,24V TRANSFORMER
(REQUIRED IF DEFROST OPTION IS USED)
TRANSFORMER MOUNTED IN ELECTRICAL BOX
OTl-iRELAY
DISCHARGE
BOARD
DEFROST OPTION
]
REMOVE JUMPER IF
OUTDOOR THERMOSTAT
FIRRRRRRRRR
I
]
DISCONNECT
TRANSFORMER
IN
FURNACE
AND CONNECT
NEW
TRANSFORMER SECONDARY {24V)
DTRI-I
A30
TO FURNACE
sz6 N
/
/
r
/-.JUMPER MUST BE REMOVED
/IF
DEFROST OPTION
/KIT
OUTDOOR
THERMOSTAT
(OPTIONAL)
WARM
IS USED
Z4VACPOWER DIR
R
BLOWER
2
/
WIRING
LUUUUUUUUUUI
FUR C
'VA° OI'C-&l
IS USEO_
7
/
G
COMMON
INDOOR
/
/
/
II
I_l
- I
91 G
75VA,24.V
TRANSFORMER
W
3I WARM
COOL
COOL
"11
"-O
(.Q
(D
4_
(_"
C
"
0 C
0 o
O R
24VAC COMMON
(CD
G
0
R
0
YI
0
INDOOR BLOWER
24VAC
POWER
IST STAGE COOL/HEAT
HEAT
LIST
YI
Yi
0
YZ
o
0
wl
C
0
0
o
T
STAGE COOLIHEA_-_=Y,
2ND STAGE COOL
Y2
0
_
WI 0
0
2ND STAGE COOL '/_
AUXILIARY
0
REVERSING
T
0
E
0
L
0
HEAT
VALVE
AMBIENT SENSOR
"/_
EMERGENCY HEAT
SERVICE LIGHT ZZiX
(_)
Y2
DLIO
0 _ w,
DEFROST DETECT
b_
Y2 (_
PUMP
REVERSING VALVE
AMBIENT SENSOR Z_
T
24VAC POWER
24VAC COMMON
SERVICE LIGHT
R
OE
0 @1
0 0
00
0 L_R_,_
0
Z_
(2 SEC
DELAY)
A2g
Z_
ROOM
THERMOSTAT
5
0
z
i
_
POSITION JUMPER THERMOSTAT.
(JR3) ON %2 (SHOWN)
WHITE-RODGERS
IF GE OR FOR
HONEYWELL
THERMOSTAT
USED, SWITCH JUMPER
(JR3) TO POSITION 2-3.
JR5
SERVICE LIGHT
OPTION BOARD
DE -/
TYP
LWR
TYP
Y TO YI CONNECTION
REQUIRED
IN SURELIGHT
APPLICATIONS
ONLY TO ENSURE INDOOR SLOWER
OPERATION
ON COOLING SPEED DURING HEAT PUMP
OPERATION.
A31
/2'_
FM21 Heat Pump Control
NOT USED ON ALL UNITS
A
Z_
DL10 NOT USED WHEN DTRI-1
IS INSTALLED.
FM21 SCHEMATIC
DIAGRAM
FM21
AMB
COMP
THERM
[_ STG
2COOL
24V
PWR
_,MB COMP
q_J
THERMISTER
STG 2 COOL
12Kq
24V PWR
r_
Y1
24V POWER
-4
8
q4
[_]qAUX
HEAT
1K-1
COOL
4Kq
DEFR
MODE
OST
[]
_
_mO4_
_
DEFROST
LED
0 :_
[_
-N
[]
c
[]
o
m
COOL
o
o
_
;U
Z
>
STG_COMP
REMOVE
JR2
JUMPER
WHEN
OUTDOOR
i
m
;u
OUTDOOR
T'STAT
(OPT)
0
O0
A
T'STAT IS
USED.
D
REV VALVE
O>
m
[]
I
COOL
24V COM
12K
MODE
[]
2K_1
AUX HT
[_
FAN
[_
EM HEAT
E_
COM
Y1 OUT
SERV LIGHT
K
Y1 IN
8K-1
COMP FAN
LOW VOLTAGE
FIELD WIRING
CONNECTIONS
DISCHARGE
T'STAT
BOARD
(DEFROST
HT. OPT.
DTRI-1 )
S89
STAT
FURNACE
SUPPLY
D]SCHARGE
T'STAT
OPEN 90F
CLOSE 80F
6K
8K
DEF/COOL
COMP
MODE
FAN
SLC1 OPTIONAL
SERVICE LIGHT
BOARD
Z_
z_
POSITION 1-2 SHOWN - USED
FOR WHITE-RODGERS
ROOM
T'STAT. tF GE OR HONEYWELL
T'STAT IS USED, SWITCH
JUMPER TO POSITION 2-3.
$54 NOT STANDARD ON MERIT
HEAT PUMPS. KITAVAILABLE.
Wiring Connections
This diagram represents the internals of the FM21.
Operating
Sequence
The diagrams on the following pages show the sequence of events which take place during normal
operation. During most normal operation, an input received from the indoor thermostat will evoke a
response in the furnace or heat pump.
Page 5
ALTERNATE
Z_
MOST UNUSED
ROOM
THERMOSTAT
THERMOSTAT
TERMINALS
NOT SHOWN.
Z_
SERVICE LIGHT CONNECTION
USED ONLY WITH HEAT
PUMPS EQUIPPED WITH $54 SERVICE LIGHT T'STAT.
$54 AVAILABLE IN MONITOR KIT #76F53.
z_
JR 3 SET FOR "WR TYR", SERVICE LIGHT ENERGIZED
WHEN 24VAC IS APPLIED TO T'STAT TERMINAL L.
AA
ELITE
THERMOSTAT
# 49M57
"-0
cc_
c C)_-G
RO_
RC)_--
YI
Z_
DURING
MANUAL
SWITCH
w2"O
DSL-450
DSL-600
OF AUXIALARY
24V
#32M07
#13K97
L22 #91H72
L23 #91H73
O REMOVE
$26
OUTDOOR
THERMOSTAT
z_(OPTIONAL)
G
_
G
(_
R
_
R
([_
YI
O
W1
YI
w20 L
OlBC_
RS20
RS+V
RS1
E
--
CF_
L_
OUTDOOR
REQUIRES
SENSOR
IF USED
SEPARATE 3-21RE
CABLE FROM T'STAT, 22AWG
MINIMUM, 300 FT. MAX.
TO HUMIDIFIER
--
RELAY IF USED.
DEHUMIDIFICATION
CONTROL, IF USED
CONNECT TO FURNACE DS ON VARIABLE
SPEED MODELS (REMOVE DS*R JUMPER).
THE FM21 OUTDOOR T'STAT & THE ROOM T'STAT
OUTDOOR SENSOR SHOULD NOT BOTH BE USED.
USE ONE OR THE OTHER. USE OF BOTH SENSORS
CREATES BALANCE POINT CONFLICT.
Z_
CHANGE
T'STAT
FACTORY
SETTING
INSTALLER SETUP
#29 FROM "0" TO "1"
TO ENERGIZE
REVERSING VALVE
O/B/TERMINAL
IN
COOLING (sEE
T'STAT INSTALLATION
MANUAL).
DO NOT USE ELITE, SIG,, DSL T'STATS WITH FM21 WHEN
DEFROST HEAT OPTION MODULE tS USED ON FM21 (NO
EM, HT, 24V OUTPUT TERMINAL ON STAT).
L O
1
BLOWER
1ST STG COOL/HEAT
AUXILIARY
O
COOL
24VAC POWER
2ND STG COOL
E
COMMO
3
COMMON
INDOOR
w_ O
o O
O
2
1 WARM
Y20
T
I
/
JUMPER
OUTDOOR
IsIFOUTDOORusED
STAT/
THERMOSTAT
TYPICAL
ROOM
THERMOSTAT
(_
OUTDOOR
SENSOR,
IF USED.
REQUIRES SEPARATE CABLE
FROM T'STAT TWISTED PAIR.
MIN. 22AWG, 300 FT. MAX.
MUST NOT BE CONNECTED.
(EUTE T'STAT DOES
NOT HAVE AN ADD HUMIDITY FUNCTION.)
"R" TO "E")
T8611G
2101
(2000 SERIES)
# 37L60
_
Y2
HC_
DC_
THE ELITE & SIG. T'STATS AUTOMATICALLY
TURN
ON THE BALANCE POINT FUNCTIONS
WHEN THE
OUTDOOR SENSOR IS CONNECTED.
THE ELITE &
SIG. T'STATS CANNOT READ THE OUTDOOR TEMP.
WITHOUT EMPLOYING
THE BALANCE POINT
FUNCTION. IF DISPLAYING THE OUTDOOR TEMP. OR
USING OUTDOOR SENSOR FOR THE HUMIDITY
FUNCTION, THE FM21 $26 OUTDOOR THERMOSTAT
FROM
24VAC
42)
L Q)@
TO FM21 CONTROL
HEAT MODE.
HEAT JUMPER
C)_--
w2'_ I
-(3
EMERGENCY
MAY BE WIRED
EIW17( m,
43
Z_
WRVAC INPUT
W2 IS THE 1ST STAGE
E,_YI TO W2.
Y/ O_-Y20_--
(_
Y2 O_
CONNECTIONS
A
SIGNATURE
THERMOSTAT
# 51M28
G O_
WiRiNG
E,_Y1 OF THE THERMOSTAT
IS THE 1ST STAGE OF
EMERGENCY
HEA1L DO NOT CONNECT THE E INPUT
(OPTIONAL
z_
AND
THE E INPUT OF THE FM21 IS USED ONLY WHEN A
DTRI _1 BOARD IS USED. THE E INPUT REQU IRES A
CONSTANT
Z_
Z_
JUMPERS
HEAT
REVERSING
AMBIENT
EMERGENCY
SERVICE
VALVE
SENSOR
HEAT
LIGHT
©
/
G60UHV/G61MPV
O
WITH FM21, HPXA19
(DTI-1)
DISCH. STAT
CLOSED WHEN
COOL
OR NORMAL HEAT PUMP OPERATION
SEE
I THERMOSTAT
BE SET FOR DUAL FUEL
SEQUENCE OFMAY
OPERATION
& SIGNATURE
THERMOSTAT
51 M28
1
2
$89
I
°000°000
PLUGS INTO THE
DISCHARGE
THERMOSTAT
|
PROBE
000°0
G60U HV/G61 MPV
/
_:D
OUTDOOR SENSOR REQUIRES SEPARATE
CABLE FROM T'STAT TWISTED PAIR. MIN.
22AWG 300 FT. MAX.
O
FM21-I
BOARD
REMOVE
JUMPER
IF OUTDOOR STAT
IS USED
"-O
]
DTRI-1 JUMPER
REVA O
REMOVE
IF DTRI-1 BOARD
_o
FURNACE
DO NOT CONNECT
"1'
SIGNATURE
DO NOT CONNECT
"2'
2
COMMON
THERMOSTAT
CAT# 51 M28
DO NOT CONNECT
"3'
3
COOL
__ R
1 WARM
THERMOSTAT
_c
HEAT PUMP
G
R
_)
Y1
_
O
Y1
HEAT PUMP
Y2
W1
Y2
Q
DO NOT CONNECT
"E'
O
THERMOSTAT
Q
T
R
£Sb'H_Z
FM21 FUELMASTER
Y1
Y2
O
Wl
4Do
©c
OT
OR
OL
Wl
@ 0
® T
@ E
DS
Y1
W2
IS USED
OUTDOOR
THERMOSTAT
®
@
O
HPXA19,HP21
HPXA12,HPXB15
_)
C
_)
Wl
75VA, 24V
TRANSFORMER
OIL FURNACE
WITH FM21, HEAT PUMP AND HEAT PUMP THERMOSTAT
DISCHARGE
THERMOSTAT
PROBE
DISCH. STAT
(DT1-1)
CLOSED WHEN
COOL
O
O
1
2
16J93
DEFROST
CONTROL
NOTE:
75VA, 24V TRANSFORMER
REQUIRED,
MOUNTED IN ELECTRICAL BOX
NOTE - IF OPTIONAL
OUTDOOR TEMR
SENSOR tS USED,
DO NOT USE 56A87
OUTDOOR T'STAT.
EXTERNAL
000°0
00o 000
o 000_
I.ENNDXO
PLUGS INTO THE F
FM2%1 BOARD
"0
56A87
OUTDOOR
THERMOSTAT
(OPTIONAL)
R
O
Y
BOARD
Y2
w@
o@
w1
_o
T
E©
@
©
E
75VA, 24V
TRANSFORMER
O
h
FURNACE
C
R
G
c
Y1
O
HEAT PUMP
THERMOSTAT
JUMPER
IF DTR%l
IS USED
COOL
THERMOSTAT
O
REMOVE
COMMON
co
G
REVA
@REMOVE JUMPER
IF OUTDOOR STAT
IS USED
OUTDOOR
THERMOSTAT
WARM
DTRI-1
_
0000
48G95
RELAY
OIL FURNACE
WITH HONEYWELL
ST9103A CONTROL
w
F
HEAT PUMP
J
HEAT PUMP
@
©
©
0000
_} wl
000
©o
©c
O
©
©
I_ENNDX
FM21-1 REVA
16J92 FM21
HEAT PUMP CONTROL
Y1
Y2
:
Q
_)
@
R
48G95
RELAY
FM21 COOLING SEQUENCE - WITHOUT DEFROST OPTION
ii!!i_ii!_ iiliiiitj_
i!_
YI
o
_'--
Operating Sequence - Cooling:
The diagram above shows the input and output signals in the
FM21. The following operating sequence steps through the inputs (left side of diagram) and the resulting outputs (right side
of diagram).
CONDITION:
With or Without Outdoor Thermostat
Constant Fan - Fan Switch "ON"
Blower (G) - Thin Black Line
1 - Blower demand from the thermostat passes directly through the
FM21 to energize the furnace blower on high speed.
12 3 4 -
Page 9
IST
STAGE COOL/HEAT
_¸ _b_
_
YI
o o
CONDITION:
Cooling - Fan Switch "ON" or "AUTO"
Compressor (Y1) - Heavy Black Line
Reversing Valve (O) - Heavy Gray Line
Reversing valve (O) is immediately energized when the indoor
thermostat is switched to cooling.
On a call for first stage cooling (Y1 & G), indoor blower is energized on high speed and compressor is energized on low speed.
Additional second stage cooling (Y2), compressor is energized on
high speed.
Outdoor Thermostat (if used) has no effect on cooling.
FM21 COMPRESSOR
HEATING SEQUENCE - WITHOUT DEFROST OPTION
....
:iii iiii!iii!iiiii:
iiiiii!ii::: :iii iiiii!
jii!ii_i!:i!!i_
•
.-o,
...............
IST
G (_-
YI
_:
INDOORBLOWER
__ST STAGE COOL/Ia_AT
Y2
_""""'i
STAGE CO(]L/HEAT
END STAGE COOL
_
y:_
CI::_
¸' !
YI
,z
iiii!i
a
Operating Sequence - Compressor
Heating:
The diagram above shows the inputs and outputs of the FM21.
The following operating sequence steps through the inputs (left
side of diagram) and the resulting outputs (right side of diagram).
CONDITION:
Constant Fan - Fan Switch "ON"
Blower (G) - Thin Black Line
1 - Blower demand from the thermostat passes directly through the
FM21 to energize the blower in the furnace on high speed.
2-
CONDITION:
Heating - Fan Switch "ON" or "AUTO"
Without Outdoor Thermostat
or
With Warm Outdoor Thermostat
Compressor
(Y1) - Heavy Black Line
Compressor
(Y2) - Heavy Gray Line
1 - On a call for first stage heating (Y1 & G), indoor blower is energized
Page 10
on high speed and compressor is energized on low speed.
Additional second stage heating (Y2 - if thermostat has 2nd stage
compressor output during heating) energizes the compressor on
high speed,
NOTE - Lennox two-speed heat pumps automatically energize
high speed when outdoor temperature drops below setpoint of
speed control thermostat.
CONDITION:
With Cold Outdoor Thermostat
Furnace (W) - Heavy Black Dashed Line
When outdoor thermostat drops to cold position, compressor (Y1
and Y2) outputs are immediately de-energized. Indoor blower
stops operating and furnace output (W) is energized. When heat
exchanger warms up, furnace energizes indoor blower on low
speed.
FM21 AUXILIARY HEATING SEQUENCE - WITHOUT DEFROST OPTION
;i:iii:iiiii_ii
Operating Sequence - 1st Stage Heating:
The diagram above shows the inputs and outputs of the FM21.
The following operating sequence steps through the inputs (left
side of diagram) and the resulting outputs (right side of diagram).
CONDITION:
Auxiliary Heating
With or Without Outdoor Thermostat
Auxiliary Heat (Wl) - Heavy Black Line
1 - On a call for auxiliary heating (Y1, Wl & G inputs), compressor (Y1
and Y2) outputs are immediately de-energized. Indoor blower stops
operating and furnace output (W-output) is energized. When heat
exchanger warms up, furnace energizes indoor blower on low
speed.
Page 11
FM21 EMERGENCY HEATING SEQUENCE - WITHOUT DEFROST OPTION
i ....................
I ...................................
i!i i iii iiii
i!iiiii
iiiii,i
I'I
!i:;;iiii
iliiiiiiiiiiiiiiiiii!i
!ii:i
Operating Sequence - Compressor
Heating:
The diagram above shows the inputs and outputs of the FM21
The following operating sequence steps through the inputs (left
side of diagram) and the resulting outputs (right side of diagram).
CONDITION:
Emergency Heat Switch "ON" (E) - Heavy Black Line
1 - When the emergency heat switch is turned on, the compressor and
indoor blower are immediately de-energized by the room thermostat. The 'E" terminal (input) is energized constantly (not swtiched
by demand) as long as the Emergency Heat switch is turned on. In
this case, without the defrost option, the E terminal has no effect.
CONDITION:
Heating - Fan Switch "ON" or "AUTO"
With or Without Outdoor Thermostat
Heat Demand (Wl) while E is energized - Heavy Gray Line
1 - On a call for heating (Y1 & G), indoor blower and compressor are
locked-out while E is energized.
2- Additional heating demand (W1 - input) energizes the furnace
(W - output).
The indoor blower is energized on low speed by the furnace after
the heat exchanger warms up.
Page 12
FM21DEFROST
SEQUENCE - WITHOUT DEFROST OPTION
ii:¸¸i!iii%HAi_ii!!!
!!Hii!iii;%ii,iH_iii_
¸¸ii ii¸
i:
YI
ISTSTA_COOW_AT
YI
6
" o
''
YI
Wl
0
Ji;;!%!}
Operating Sequence - Defrost:
2 - The compressor continues operating and the furnace is not energized (locked-out in order to prevent overheating the indoor coil).
Since the furnace is locked-out and indoor coil is cool, the indoor
thermostat may call for auxiliary (W1) heating during defrost.
3 - When defrost is complete, the furnace (W - output) will be energized to satisfy remaining thermostat demand.
The diagram above shows the inputs and outputs of the FM21.
The following operating sequence steps through the inputs (left
side of diagram) and the resulting outputs (right side of diagram).
CONDITION:
Defrost Input (Wl) From Outdoor Unit - Heavy Gray Line
in conjunction with
Heating Demand (Y1 - input)
1 - When the FM21 senses a defrost cycle the defrost indicator LED is
energized.
1 -
Page 13
CONDITION:
Defrost Input (Wl) From Outdoor Unit - Heavy Gray Line
in conjunction with
Auxiliary Heating Demand (Y1 and W1 - input)
Not possible since outdoor unit is de-energized during auxiliary
(W1 - input) heating.
FM21COOLING
SEQUENCE
- WITH
DEFROST OPTION
i
_ i ¸_oo_
i iiili!i
oi:_i¸_0ill,i,
iiii_i:iili
i,
ii
ilil I=i
_=_
i:ii;:;::iil]i_
......:!!!!E_!i!!:!_!!Li!i!!:!_!!'!!_!!!!_!!i!!!!:L_,ii.__!iiiil;:::::(i
i _:;
YI
I ST STA6E COOL/HEAT _ii
_
i: iii=i:
YI
6
YI
_
ST STAGE COOL/HEAT
[
)
??: : i
i ii!:i Iii;! i
Operating Sequence - Cooling:
The diagram above shows the inputs and outputs of the FM21.
The following operating sequence steps through the inputs (left
side of diagram) and the resulting outputs (right side of diagram).
thermostat is switched to cooling.
2 - On a call for first stage cooling (Y1 & G), indoor blower is energized
on high speed and compressor is energized on low speed.
3 - Additional second stage cooling (Y2), compressor is energized on
high speed.
CONDITION:
Constant Fan - Fan Switch "ON"
Blower (G) - Thin Black Line
1 - Blower demand from the thermostat passes directly through the
FM21 to energize the blower in the furnace on high speed.
CONDITION:
Cooling - Fan Switch "ON" or "AUTO"
With Outdoor Thermostat
Compressor
(Y1) - Heavy Black Line
Reversing Valve (O) - Heavy Gray Line
1 - When outdoor thermostat is warm, previous sequence applies,
2- Outdoor thermostat acts as a low ambient control for the outdoor
unit, When outdoor thermostat is cold, compressor (Y1 and Y2 outputs) are de-energized and indoor blower (G output) continues to
run on high speed.
CONDITION:
Cooling - Fan Switch "ON" or "AUTO"
Without Outdoor Thermostat
Compressor
(Y1) - Heavy Black Line
Reversing Valve (O) - Heavy Gray Line
1 - Reversing valve (O) is immediately energized
when the indoor
Page 14
FM21 COMPRESSOR
HEATING SEQUENCE
'
- WITH DEFROST OPTION
!!ii!,
WARM
2
COMMON
3 cool
COOL
YI
IST
STAGE COQ./HEAT
YI
ii:il
y
ST STA6E COOL/HEAT
ii................................
ii
Operating Sequence - Compressor
Heating:
The diagram above shows the inputs and outputs of the FM21.
The following operating sequence steps through the inputs (left
side of diagram) and the resulting outputs (right side of diagram).
CONDITION:
Constant Fan - Fan Switch "ON"
Blower (G) - Thin Black Line
1 - Blower demand from the thermostat passes directly through the
FM21 to energize the blower in the furnace on high speed.
CONDITION:
Heating - Fan Switch "ON" or "AUTO"
Without Outdoor Thermostat
Compressor (Y1) - Heavy Black Line
Compressor (Y2) - Heavy Gray Line
1 - On a call for first stage heating (Y1 & G), indoor blower is energized
on high speed and compressor is energized on low speed.
2 - Additional second stage heating (Y2 - if thermostat has 2nd stage
compressor output during heating) energizes the compressor on
high speed.
NOTE- Lennox two-speed heat pumps automatically energize
high speed when outdoor temperature drops below setpoint of
speed control thermostat.
CONDITION:
With Outdoor Thermostat
1 - When outdoor thermostat is warm, previous sequence applies.
2 - If outdoor thermostat switches to cold position during compressor
heat operation, the compressor and indoor blower (Y1, Y2 and G)
outputs are immediately de-energized and the furnace (W-output)
is energized. The indoor blower stops and the fumace begins operating.
3 - When the heat exchanger warms, the indoor blower is energized
on low speed by the furnace.
4 - If the outdoor thermostat is closed when thermostat demand (Y1
and G input) begins, the compressor and indoor blower (Y1 and G
outputs) are locked-out and the furnace (W-output) is energized.
Page 15
FM21 AUXILIARY HEATING SEQUENCE - WITH DEFROST OPTION
i ..................................................................
6
Yl
sTSTA_E
COOL/HEAT
YJ
Operating Sequence - Auxiliary Heating:
The diagram above shows the inputs and outputs of the FM21,
The following operating sequence steps through the inputs (left
side of diagram) and the resulting outputs (right side of diagram).
CONDITION:
Heating - Fan Switch "ON" or "AUTO"
Without Outdoor Thermostat
Compressor
and Auxiliary Heat (Y1, Wl inputs} - Heavy
Black Line
Compressor (Y2 output) - Heavy Gray Line
Blower (G input) - This Black Line
1 - On a call for auxiliary heating (Y1, Y2, W1 & G inputs), furnace (Woutput) is energized along with compressor (Y1 and Y2 output) and
high speed blower (G output).
NOTE - Lennox two-speed heat pumps automatically energize
high speed when outdoor temperature drops below setpoint of
speed control thermostat.
2 - When the furnace warms and the discharge thermostat opens, the
compressor and blower (Y1, Y2 and G outputs) are de-energized.
The blower returns to low speed and the furnace satisfies remaining thermostat demand.
CONDITION:
With Outdoor Thermostat
1 - When outdoor thermostat is warm, previous sequence applies.
2 - When outdoor thermostat switches to cold position, compressor
(Y1 and Y2) outputs are immediately de-energized. Indoor blower
stops operating and furnace output (W-output) is energized. When
heat exchanger warms up, furnace energizes indoor blower on low
speed.
Page 16
FM21 EMERGENCY HEATING SEQUENCE - WITH DEFROST OPTION
iJilit!_iiii_i_;;_ii;!_iil
ii_i:i!_:ili_ii_!iiiii_ii
¸ i:_i_i_i_i_X!!!i_:_
il.............................................................................
......................................................
ii
iil i!i!iii
....
z co .
.............................
..................................................................
Operating Sequence - Compressor
Heating:
The diagram above shows the inputs and outputs of the FM21.
The following operating sequence steps through the inputs (left
side of diagram) and the resulting outputs (right side of diagram).
CONDITION:
Emergency Heat Switch "ON" (E) - Heavy Black Line
1 - When the emergency heat switch is turned on, the compressor and
indoor blower are immediately de-energized. The "E" terminal (input) is energized constantly (not swtiched by demand) as long as
the Emergency Heat switch is turned on. With the defrost heat option, the E terminal input energizes a relay in the defrost board to
drop the G fan signal to the furnace and the Y1 signal to the compressor if the unit is in a defrost cycle.
CONDITION:
Heating - Fan Switch "ON" or "AUTO"
With or Without Outdoor Thermostat
Heat Demand (Wl) while E is energized - Heavy Gray Line
1 - On a call for heating (Y1 & G), indoor blower and compressor are
locked-out while E is energized.
2- Additional heating demand (W1 - input) energizes the furnace
(W - output).
The indoor blower is energized on low speed by the furnace after the
heat exchanger warms up.
Page 17
FM21DEFROST
y_/_ii_
SEQUENCE - WITH DEFROST OPTION
_i¸¸
:iii
WARM
, ,,iiii
iii iii' ii
w _o_
YI
i,
....
_
w
_STSTAee
COOL,_A_
_
i
i
i
yi
:!
YI _ Isx STA6E
_OL/_AT
YI
>
i
Operating Sequence - Defrost:
The diagram above shows the inputs and outputs of the FM21.
The following operating sequence steps through the inputs (left
side of diagram) and the resulting outputs (right side of diagram).
CONDITION:
Defrost Input (Wl) From Outdoor Unit - Heavy Gray Line
in conjunction with
Heating Demand (Y1 - input)
1 - When the FM21 senses a defrost cycle the defrost indicator LED is
energized.
2 - The compressor continues operating and the furnace (W output is
energized. The furnace operates during defrost.
NOTE- Lennox two-speed heat pumps automatically energize high
speed when outdoor temperature drops below setpoint of speed
control thermostat..
3 - During defrost, the furnace is cycled on and off by the discharge
thermostat in order to control discharge air temperature.
4 - When defrost is complete, heating demand will be satisfied by either
the furnace or heat pump based on whether the furnace is on or off at
the time the defrost terminals.
If the furnace is ON when the defrost terminates ($89 closed), the furnace will satisfy the Y1 demand.
If the fumace is OFF when the defrost terminates ($89 open) both the
heat pump and furnace will remain off until $89 cools and closes.
When $89 closes, the heat pump will satisfy the Y1 demand.
CONDITION:
Defrost Input (Wl) From Outdoor Unit - Heavy Gray Line
in conjunction with
Auxiliary Heating Demand (Y1 and W1 - input)
1 - Not possible since outdoor unit is de-energized during auxiliary (Wl
- input) heating.
Page 18
FM21SERVICELIGHT
SEQUENCE - WITH OR WITHOUT DEFROST OPTION
!"!£_i_©_
__i¸
i i_ ¸_0_i !
v,.............
_
,sTSTA,_
C_,_AT
!iI................................
!i_
ii_
.................................
V,
iii!!!
i i: i:
ii
L
iii ..................................
_i!_:_i_!i[i];iiii!!ii:!_ii_ii_!i_i_
¸
..................................iil
Operating Sequence - Service Light:
The diagram above shows the inputs and outputs of the FM21.
The following operating sequence steps through the inputs (left
side of diagram) and the resulting outputs (right side of diagram).
CONDITION:
Compressor Input (Y1) From Indoor Thermostat - Heavy
Gray Line in conjunction with
Service Light (L - input from outdoor unit) and
Auxiliary Heat (W1 - Input from Indoor Thermostat)
1 - When the FM21 senses a closed defrost thermostat during a heating
cycle, the SLCl will begin a 5-1/2 minute (330 sec.) time delay.
2 - If auxiliary heat demand is received after the time delay, the SLCl
energizes the 'L" terminal (output to indoor thermostat) and the service light is energized.
Page 19
TABLE 1
FM21 OPERATION and TROUBLESHOOTING
(FM21 Basic Unit)
Response
Input
Unit
Mode
Room
G
I
Y1
Thermostat
Y2
Wl
OFF
OFF
I
O
[o_l
[o_J
"U
c,Q
cD
o
_1
OFF
_J
OFF
OFF
Defrost
)_1
D_ii
O
W
OFF
OFF
[o_
OFF
OFF
[o_
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
[o]_l
OFF
OFF
G
I[o]_l
OFF
OFF
I[o]_l
OFF$
OFF
OFF
OFF$
OFF
OFF
OFF$
OFF
I[o]_l
OFF
OFF$
OFF
I[o]_l
During
[o_
W1 *
OFF
OFF
[o_J
OFF
Y2
OFF
OFF
Defrost During
Primary Heat
Y1
OFF
Auxiliary
Heating
Emergency
Heating
E
OFF
[o_J
Primary
Heating
Furnace
Heat Pump
*Actually an input used to detect defrost, "On" indicates defrost is bein_ sensed.
**Even though FM21 provides Y2 output, high speed heating is controlled by heat pump in Lennox two speed units.
***Latched in state until Y1 goes off.
tMost heat pump thermostats do not provide Y2 (high speed compressor) output during heating.
$FM21 output is off but voltage from outdoor unit may be measured in some Lennox units.
TABLE 2
FM21 OPERATION and TROUBLESHOOTING (FM21 with Outdoor Thermostat Option)
Input
Room
Unit
Response
Thermostat
Outdoor
Terminal
Y1
Mode
Cooling
Primary
Heating
G
2-3
Thermostat
Terminal
Y2
W1
E
OFF
OFF
OFF
OPEN
OFF
OPEN
I
im-OFF
(Closed When
Cold)
OFF
OFF
OPEN
OFF
OFF
OPEN
OFF
OFF
OPEN
OFF
OFF
OPEN
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
Heat
Pump
Furnace
1-2
(Closed When
Warm)
Y2
OFF
OFF
H
OFF
[o_o_.']_l_
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
"U
c,Q
cD
Auxiliary
Heating
OPEN
OPEN
OFF
Emergency
Heating
OFF
OPENtt
Defrost During
Primary Heat
OPENtt
OPENtt
Defrost During
Auxiliary Heat
OPENtt
*Actually an input used to detect defrost. "On" indicates defrost is being sensed.
**Even though FM21 provides Y2 output high speed heating is controlled By heat pump in Lennox two speed units.
***Latched in state until Y1 goes off.
tMost heat pump thermostats do not provide Y2 (high speed compressor) output during heating.
$FM21 output is off but voltage from outdoor unit may be measured in some Lennox units.
tSHeat pump cannot go into defrost when outdoor temp. is cold since heat pump unit is de-energized. However, if outdoor thermostat
and the furnace completes the heating cycle.
switches to cold position during a defrost cycle, compressor
is de-energized
TABLE 3
FM21 OPERATION and TROUBLESHOOTING
(FM21 with Defrost Option)
Input
Unit
Mode
Response
Room
Thermostat
Discharge
Thermostat
Heat
Y2
Wl
OFF
OFF
[o]J_l
OFF
[o_J
OFF
[o_l
OFF
OFF
OFF
[o_l
OFF
[o_J
OFF
[o_l
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
[o_
OFF
OFF
OFF
OFF
OFF
[o_
OFF
OFF
OPEN
OFF
OFF
OFF
OFF
OPEN
OFF
Pump
Furnace
Terminal 1-2
Y1
Cooling
[o_l
Eo]J_l
Primary
Heating
OFF
Auxiliary
Heating
OFF
Emergency
Heating
OFF
Primary Heat
INN
IHH
OFF
OFF
OFF
OFF
WI*
O
W
OFF
[o_J
OFF
Eo]_l
OFF
[o_J
OFF
[o]_J
OFF
[o_J
OFF
[o_l
OFF
[o_J
OFF
OFF
OFF
OFF
OFF
[o]_,J
[o]_r-_J
OFF
OFF
OFF
[o]_J
OPEN
OFF
OFF
OFF
OFF
OFF
[o]_J
OPEN
OFF
OFF
OFF
OFF
OFF
[o]_J
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
[o]_o_.']_l_
[o]_o_.']_l_
OPEN
[o]_,J
OFF$
OFF
OFF
OFF$
OFF
OFF
OFF$
OFF
OPEN
[o]_J
OFF
OFF$
OFF
OPEN
[o]_J
[o_
OFF$
OFF
OFF$
OFF
[o_
OFF$
OFF
[o_
OFF$
OFF
*Actually an input used to detect defrost. "On" indicates defrost is being sensed.
**Even though FM21 provides Y2 output, high speed heating is controlled By heat pump in Lennox two-speed
***Latched in state until Y1 goes off.
tMost heat pump thermostats do not provide Y2 (high speed compressor) output during heating.
$FM21 output is off but voltage from outdoor unit may be measured in some Lennox units.
Y2
OPEN
OFF
Oe,roat
Oaring
INN
Auxiliary
Heat:_
Y1
OFF
OFF
OFF
OFF
Defrost During
(Closed When
Cold)
[o]_r-_J
OFF
OFF
[o]_|.....
_1]11
OFF$
[o]_J
[o]_J
OFF$
OFF
[o]_J
[o]_J
OFF$
OFF
[o]_J
OFF$
[o]_J
Eo]_J
OFF$
[o]_J
Eo]_J
OFF$
OFF
[o]_J
OFF$
OFF
[o]_J
OFF
E_o_
OPEN
[o]_J
[o]_J
OFF
OFF
OFF
OFF$
OFF
OFF
units.
¢_-Whendefrost is complete, heating demand will be satisfied by either the furnace or heat pump based on whether the furnace is on or off at the _me the defrost terminals.
If the furnace is ON when the defrost terminates (S89 closed), the furnace will satisfy the Y1 demand.
If the furnace is OFF when the defrost terminates (S89 open) both the heat pump and furnace will remain off until S89 cools and closes. When S89 closes, the heat pump will satisfy the Y1
demand.
TABLE 4
FM21 OPERATION and TROUBLESHOOTING
(FM21 with Defrost Option and 51M28 or 49M57 Thermostat)
Input
Room Thermostat
Unit
Mode
G
Y1
Cooling
[o_l
Primary
Heating
Eo]_J
"0
Discharge
Thermostat
E
NA
Wl
OFF
OFF
Eo]_J
OFF
[o_J
OFF
Eo_l
OFF
OFF
OFF
Eo_l
OFF
OPEN
[o_J
OFF
Eo_I
OFF
OPEN
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
Emergency
Heating
Emergency
[o_l
Defrost During
Primary Heat
Eo]_J
OFF
INN
IHH
OFF
OFF
OFF
Heat Pump
Y1
Y2
OFF
OFF
WI*
Furnace
O
W
OFF
[o_J
OFF
Eo]II
OFF
[o_J
OFF
Eo]_J
OFF
[o_J
OFF
Eo_l
OFF
OPEN
OFF
OPEN
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
Eo]_J
OFF$
Eo]_J
OFF$
Eo]J_l
OFF$
OFF
Eo]J_l
Eo]_J
OFF$
OFF
Eo]_J
Eo]_J
OFF$
Eo]_J
Eo]_J
OFF$
Eo]_J
Eo]J_l
OFF$
OFF
Eo]J_l
Eo]_J
OFF$
OFF
Eo]ll
heat is function of the thermostat.
OFF
OFF¢
OFF
OFF
OFF$
OFF
OFF
OFF$
OFF
OPEN
OFF
OFF$
OFF
OPEN
[o_
OFF$
OFF
OFF$
OFF
[o_
OFF$
OFF
[o_
OFF$
OFF
Oe,roetOaring
INN
Auxiliary
HeatY_
Terminal 1-2
(Closed When
Cold)
Y2
OFF
Auxiliary
Heating
c,Q
cD
Response
*Actually an input used to detect defrost, "On" indicates defrost is being sensed.
**Even though FM21 provides Y2 output, high speed heating is controlled By heat pump in Lennox two-speed
***Latched in state until Y1 goes off.
tMost heat pump thermostats do not provide Y2 (high speed compressor) output during heating.
$FM21 output is off but voltage from outdoor unit may be measured in some Lennox units.
<>Simultaneous Y and W demand will not occur if thermostat is set to add-on dual fuel.
OFF
OFF
OPEN
OFF
Eo]_J
units.
€_-Whendefrost is complete, heating demand will be satisfied by either the furnace or heat pump based on whether the furnace is on or off at the time the defrost terminals.
If the furnace is ON when the defrost terminates (S89 closed), the furnace will satisfy the Y1 demand.
If the furnace is OFF when the defrost terminates (S89 open) both the heat pump and furnace will remain off until S89 cools and closes. When S89 closes, the heat pump will satisfy the Y1
demand.
FM21 OPERATION and TROUBLESHOOTING
Unit
11
Room Thermostat
Mode
G
Y1
TABLE 5
(FM21 with Outdoor Thermostat and Defrost Options)
Response
Inl,ut
Outdoor Thermostat
Terminal 2-3
(Closed When
Cold)
Terminal 1-2
(Closed When
Warm[
OPEN
OPEN
I
Heat Pump
Thermostat
Discharge
Terminal 1-2
(Closed When
Cold)
OPEN
Y1
Y2
OFF
OFF
OFF
OFF
Furnace
OFF
OPEN
Cooling
OPEN
OPEN
OPEN
OPEN
OFF
OPEN
OPEN
OFF
OPEN
OPEN
OFF
OPEN
OPEN
OPEN
Primary
Heating
OPEN
OPEN
OPEN
"0
OPEN
OPEN
OPEN
OPEN
OPEN
OPEN
OPEN
OPEN
OPEN
Auxiliary
Heating
OPEN
OPEN
OPEN
OPEN
OPEN
OPEN
OPEN
OPEN
OPEN
OPEN
Emergency
Heating
OPEN
Defrost
During
Primary
Heat
OPENer
OPENtt
Defrost
During
Auxiliary
Heat_<
OPEN
OPEN
OPEN
OPEN
OPENtt
OPEN
OPENtt
OPEN
OPENtt
OPENtt
OPENtt
OPEN
OPENtt
OPEN
*Actually/an input used to detect defrost. "On" indicates defrost is bein 9 sensed.
**Even mough FM21 provides Y2 output, high speed heating is controued By heat pump in Lennox two speed units.
***Latched in state untiI Y1 goes off.
tMost heat pump thermostats do not provide Y2 (high speed compressor) output durin 9 heating.
$FM21 output is off but voltage from outdoor unit may be measured in some Lennox units.
ttHeat pump cannot go into defrost when outdoor temp. is cold since heat pump unit is de-energized. However, if outdoor thermostat switches to cotdposition during a defrost cycle, compressor is de-energized.
_-When defrost is complete, heating demand will be satisfied by either the furnace or heat pump based on whether the furnace is on or off.at the time the defrost terminals.
If the furnace is ON when the defrost terminates
(S89 closed), the furnace will satisfy the Y1 demand.
If the furnace is OFF when the defrost terminates ($89 open) both the heat pump and furnace will remain off. un_l S89 cools and closes. When $89 closes, the heat pump will satisfy the Y1
demand.
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