
Typical wiring diagram for heat only,
3-wire, single transformer systems
RH
24 VAC 120 VAC
Hot
Neutral
THERMOSTAT
SYSTEM
G W
TRANSFORMER
Heating
System
Fan
Relay
YC‡RC
JUMPER
WIRE
OB
For 2-wire Heat only,
attach to RH and W
NOTE
Typical wiring diagram for cool only,
3-wire, single transformer systems
RH
Y
24 VAC 120 VAC
Hot
Neutral
TRANSFORMER
THERMOSTAT
SYSTEM
G W
Cooling
System
Fan
Relay
RCOB
C‡
JUMPER
WIRE
Typical wiring diagram for heat/cool,
4-wire, single transformer systems
RH
Y
24 VAC 120 VAC
Hot
Neutral
THERMOSTAT
SYSTEM
G W
TRANSFORMER
Heating
System
Fan
Relay
Cooling
System
RC
JUMPER
WIRE
OC‡B
RED jumper wire (provided with thermostat) must be
connected between thermostat RH and RC terminals
for proper thermostat operation with this system.
NOTE
Typical wiring diagram for heat/cool,
5-wire, two-transformer systems
RH
Y
24 VAC 120 VAC
Hot
Neutral
THERMOSTAT
SYSTEM
G W
HEATING
TRANSFORMER
Heating
System
Fan
Relay
Cooling
System
RC
24 VAC 120 VAC
Hot
Neutral
COOLING TRANSFORMER
OBC‡
Typical wiring diagram for heat pump
with reversing valve energized in COOL
RH
Y
24 VAC 120 VAC
Hot
Neutral
THERMOSTAT
SYSTEM
G W
TRANSFORMER
Reversing
Valve*
RCOBC‡
JUMPER
WIRE
Compressor
Contactor
JUMPER
WIRE
* Reversing valve is energized when the
system switch is in the COOL position
Fan
Relay
Typical wiring diagram for heat pump
with reversing valve energized in HEAT
RH
Y
24 VAC 120 VAC
Hot
Neutral
THERMOSTAT
SYSTEM
G W
TRANSFORMER
Reversing
Valve*
RCO
B
C‡
JUMPER
WIRE
Compressor
Contactor
JUMPER
WIRE
* Reversing valve is energized when the
system switch is in the HEAT position
Fan
Relay
Typical wiring diagram for heat only,
3-wire, single transformer systems
RH
24 VAC 120 VAC
Hot
Neutral
THERMOSTAT
SYSTEM
G W
TRANSFORMER
Heating
System
Fan
Relay
YC‡RC
JUMPER
WIRE
OB
For 2-wire Heat only,
attach to RH and W
NOTE
Typical wiring diagram for cool only,
3-wire, single transformer systems
RH
Y
24 VAC 120 VAC
Hot
Neutral
TRANSFORMER
THERMOSTAT
SYSTEM
G W
Cooling
System
Fan
Relay
RCOB
C‡
JUMPER
WIRE
Typical wiring diagram for heat/cool,
4-wire, single transformer systems
RH
Y
24 VAC 120 VAC
Hot
Neutral
THERMOSTAT
SYSTEM
G W
TRANSFORMER
Heating
System
Fan
Relay
Cooling
System
RC
JUMPER
WIRE
OC‡B
RED jumper wire (provided with thermostat) must be
connected between thermostat RH and RC terminals
for proper thermostat operation with this system.
NOTE
Typical wiring diagram for heat/cool,
5-wire, two-transformer systems
RH
Y
24 VAC 120 VAC
Hot
Neutral
THERMOSTAT
SYSTEM
G W
HEATING
TRANSFORMER
Heating
System
Fan
Relay
Cooling
System
RC
24 VAC 120 VAC
Hot
Neutral
COOLING TRANSFORMER
OBC‡
Typical wiring diagram for heat pump
with reversing valve energized in COOL
RH
Y
24 VAC 120 VAC
Hot
Neutral
THERMOSTAT
SYSTEM
G W
TRANSFORMER
Reversing
Valve*
RCOBC‡
JUMPER
WIRE
Compressor
Contactor
JUMPER
WIRE
* Reversing valve is energized when the
system switch is in the COOL position
Fan
Relay
Typical wiring diagram for heat pump
with reversing valve energized in HEAT
RH
Y
24 VAC 120 VAC
Hot
Neutral
THERMOSTAT
SYSTEM
G W
TRANSFORMER
Reversing
Valve*
RCO
B
C‡
JUMPER
WIRE
Compressor
Contactor
JUMPER
WIRE
* Reversing valve is energized when the
system switch is in the HEAT position
Fan
Relay
Typical wiring diagram for heat only,
3-wire, single transformer systems
RH
24 VAC 120 VAC
Hot
Neutral
THERMOSTAT
SYSTEM
G W
TRANSFORMER
Heating
System
Fan
Relay
YC‡RC
JUMPER
WIRE
OB
For 2-wire Heat only,
attach to RH and W
NOTE
Typical wiring diagram for cool only,
3-wire, single transformer systems
RH
Y
24 VAC 120 VAC
Hot
Neutral
TRANSFORMER
THERMOSTAT
SYSTEM
G W
Cooling
System
Fan
Relay
RCOB
C‡
JUMPER
WIRE
Typical wiring diagram for heat/cool,
4-wire, single transformer systems
RH
Y
24 VAC 120 VAC
Hot
Neutral
THERMOSTAT
SYSTEM
G W
TRANSFORMER
Heating
System
Fan
Relay
Cooling
System
RC
JUMPER
WIRE
OC‡B
RED jumper wire (provided with thermostat) must be
connected between thermostat RH and RC terminals
for proper thermostat operation with this system.
NOTE
Typical wiring diagram for heat/cool,
5-wire, two-transformer systems
RH
Y
24 VAC 120 VAC
Hot
Neutral
THERMOSTAT
SYSTEM
G W
HEATING
TRANSFORMER
Heating
System
Fan
Relay
Cooling
System
RC
24 VAC 120 VAC
Hot
Neutral
COOLING TRANSFORMER
OBC‡
Typical wiring diagram for heat pump
with reversing valve energized in COOL
RH
Y
24 VAC 120 VAC
Hot
Neutral
THERMOSTAT
SYSTEM
G W
TRANSFORMER
Reversing
Valve*
RCOBC‡
JUMPER
WIRE
Compressor
Contactor
JUMPER
WIRE
* Reversing valve is energized when the
system switch is in the COOL position
Fan
Relay
Typical wiring diagram for heat pump
with reversing valve energized in HEAT
RH
Y
24 VAC 120 VAC
Hot
Neutral
THERMOSTAT
SYSTEM
G W
TRANSFORMER
Reversing
Valve*
RCO
B
C‡
JUMPER
WIRE
Compressor
Contactor
JUMPER
WIRE
* Reversing valve is energized when the
system switch is in the HEAT position
Fan
Relay
Typical wiring diagram for heat only,
3-wire, single transformer systems
RH
24 VAC 120 VAC
Hot
Neutral
THERMOSTAT
SYSTEM
G W
TRANSFORMER
Heating
System
Fan
Relay
YC‡RC
JUMPER
WIRE
OB
For 2-wire Heat only,
attach to RH and W
NOTE
Typical wiring diagram for cool only,
3-wire, single transformer systems
RH
Y
24 VAC 120 VAC
Hot
Neutral
TRANSFORMER
THERMOSTAT
SYSTEM
G W
Cooling
System
Fan
Relay
RCOB
C‡
JUMPER
WIRE
Typical wiring diagram for heat/cool,
4-wire, single transformer systems
RH
Y
24 VAC 120 VAC
Hot
Neutral
THERMOSTAT
SYSTEM
G W
TRANSFORMER
Heating
System
Fan
Relay
Cooling
System
RC
JUMPER
WIRE
OC‡B
RED jumper wire (provided with thermostat) must be
connected between thermostat RH and RC terminals
for proper thermostat operation with this system.
NOTE
Typical wiring diagram for heat/cool,
5-wire, two-transformer systems
RH
Y
24 VAC 120 VAC
Hot
Neutral
THERMOSTAT
SYSTEM
G W
HEATING
TRANSFORMER
Heating
System
Fan
Relay
Cooling
System
RC
24 VAC 120 VAC
Hot
Neutral
COOLING TRANSFORMER
OBC‡
Typical wiring diagram for heat pump
with reversing valve energized in COOL
RH
Y
24 VAC 120 VAC
Hot
Neutral
THERMOSTAT
SYSTEM
G W
TRANSFORMER
Reversing
Valve*
RCOBC‡
JUMPER
WIRE
Compressor
Contactor
JUMPER
WIRE
* Reversing valve is energized when the
system switch is in the COOL position
Fan
Relay
Typical wiring diagram for heat pump
with reversing valve energized in HEAT
RH
Y
24 VAC 120 VAC
Hot
Neutral
THERMOSTAT
SYSTEM
G W
TRANSFORMER
Reversing
Valve*
RCO
B
C‡
JUMPER
WIRE
Compressor
Contactor
JUMPER
WIRE
* Reversing valve is energized when the
system switch is in the HEAT position
Fan
Relay
ǂ c-wire not required