3
69-2738EFS—03
Wiring
Wiring guide — conventional systems
NOTES
Wire specifications:
Use 18- to 22-gauge thermostat wire.
Shielded cable is not required.
[1]
Power supply. Provide disconnect means and
overload protection as required.
[2]
Remove jumper for 2-transformer systems.
[4]
Common connection must come from cooling
transformer.
[5]
In Installer Setup, set system type to Heat Only.
[6]
In Installer Setup, set system type to
2Heat/2Cool Conventional.
[7]
In Installer Setup, set changeover valve to O
or B.
[8]
In Installer Setup, set system type to
2Heat/1Cool Heat Pump.
[9]
In Installer Setup, set system type to
2Heat/2Cool Heat Pump.
[10]
In Installer Setup, set system type to
3Heat/2Cool Heat Pump.
1H/1C System
(1 transformer)
Rc
Power
[1]
R
[R+Rc joined by jumper]
Y
Compressor contactor
C
24VAC common
W
Heat relay
G
Fan relay
Heat-only System
Rc
Power
[1]
R
[R+Rc joined by jumper]
C
24VAC common
W
Heat relay
1H/1C System
(2 transformers)
Rc
Power (cooling transformer)
[1, 2]
R
Power (heating transformer)
[1, 2]
Y
Compressor contactor
C
24VAC common
[4]
W
Heat relay
G
Fan relay
Heat-only System
with Fan
Rc
Power
[1]
R
[R+Rc joined by jumper]
C
24VAC common
W
Heat relay
G
Fan relay
Cool-only System
Rc
Power
[1]
R
[R+Rc joined by jumper]
Y
Compressor contactor
C
24VAC common
G
Fan relay
2H/2C System
(1 transformer)
[6]
Rc
Power
[1]
R
[R+Rc joined by jumper]
Y
Compressor contactor (stage 1)
C
24VAC common
W
Heat relay (stage 1)
G
Fan relay
W2 Heat relay (stage 2)
Y2
Compressor contactor (stage 2)
2H/2C System
(2 transformers)
[6]
Rc
Power (cooling transformer)
[1, 2]
R
Power (heating transformer)
[1, 2]
Y
Compressor contactor (stage 1)
C
24VAC common
[4]
W
Heat relay (stage 1)
G
Fan relay
W2 Heat relay (stage 2)
Y2
Compressor contactor (stage 2)
See
[notes]
below
Rc
Y
W
G
R
C
MCR29439
Rc
W
R
C
MCR29440
Rc
W
G
R
C
MCR29444
Rc
Y
G
R
C
MCR29445
Rc
Y
W
G
W2
Y2
R
C
MCR29446
Rc
Y
W
G
R
C
M29443
Rc
Y
W
G
W2
Y2
R
C
M29447
