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Option 2 − CB31MV Series Blower Coil Unit & Lennox
Heat Pump &
Option 3 − G32V/G21V/ GSR21V Series Gas Furnace,
Lennox Heat Pump & FM21
1. Wire each thermostat with five−wire thermostat cable
to terminals R, Y, O, W, and C.
2. Run thermostat cable from each of the thermostats to
the control center. Mark each cable according to the
zone thermostat that it is from.
3. Strip the cables and attach each of the five wires to the
control center as shown in figures 24 and 25.
4. Heat pump thermostats are equipped with an E, an A,
and an L terminal. For Option 2, wire from the L termi-
nal to the L terminal/wire at the outdoor unit. DO NOT
wire the E or A terminals. Set heat anticipator of each
thermostat to 0.10. An outdoor thermostat is not need-
ed due to the discharge air temperature probe feature.
For Option 3, wire as shown in figure 25. DO NOT use
A terminal on thermostat. Set heat anticipator of each
thermostat to 0.10.
Pressure Switch Wiring
Option 2 − CB31MV Series Blower Coil Unit & Lennox
Heat Pump and,
Option 3 − G32V/G21V/ GSR21V Series Gas Furnace,
Lennox Heat Pump & FM21
Pull a two-wire thermostat cable from the field−installed
pressure switch to the control center. Wire the pressure
switch to the control center using thermostat wire as shown
in figure 21.
FIELD−INSTALLED
PRESSURE SWITCH
Figure 21
G32V/G21V/GSR21V Series Gas Furnace Wiring
After you have installed the furnace, field wire the unit
as shown in the installation instructions provided with
the furnace.
Option 1 − G32V/G21V/GSR21V Series Gas Furnace
& Condensing Unit
Use thermostat wire to connect the furnace and the control
center. Connections to the control center are marked as IN-
DOOR UNIT. See figure 23.
Option 3 − G32V/G21V/GSR21V Series Gas Furnace,
Lennox Heat Pump & FM21
Use thermostat wire to connect the furnace, the control cen-
ter, and the FM21 control system. Connections to the control
center are marked as INDOOR UNIT. See figure 25.
PRESSURE
SWITCH
CONTROL
CENTER
Page 20
Temperature Modulation: Switch Installation & Wir-
ing (G32V only)
Install temperature modulation switch in the supply air
plenum so that the probe is in the air stream. The switch
should be located downstream of the evaporator coil and
before the supply plenum divides into ducts. Location
should be convenient for wiring the switch to the furnace
terminal strip.
Connect a field supplied wire from the FAN LINE terminal
on the switch to the W1 terminal on the G32V furnace. Con-
nect a field−supplied wire from the FAN LOW terminal on
the switch to the W2 terminal on the G32V furnace. See
system wiring diagrams in figures 23 and 25.
Temperature Modulation: Switch Lever Settings
(G32V only)
Once installed, the temperature modulation switch must
be set to the desired supply air temperatures. Pushing the
two levers as close as possible will result in the minimum
differential. Spreading the two levers apart will result in a
higher differential. See figure 22.
TEMPERATURE MODULATION SWITCH
LEVER SETTINGS
50
100
FIRST LEVER
SET AT 100_F
(Switch Closes)
Note− Align the highest point on the lever to the corresponding desired tem-
perature setting.
Figure 22
Set the first two levers on the desired high fire (switch
opens) and low fire (switch closes) temperatures. When
supply air temperature reaches the second lever setting,
the temperature modulation switch will open to allow the
gas valve to change to low fire operation. When the supply
air temperature lowers to the first lever setting, the switch
will close to allow the gas valve to change to high fire op-
eration.
250
200
150
SECOND LEVER
SET AT 130_F
(Switch Opens)
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