publication

161 / 221

1E78-151
CONFIGURATION AND
TYPICAL WIRING DIAGRAMS
Base Back of
Thermostat Body
RC
ELEC GAS
G RH
Y O B
W
W906 W904
Elec/Gas
Switch
W903
Mounting
Hole
Mounting
Hole
W903 - clip to disable EMR feature
W904 - clip for Celcius display
W905 - clip for hydronic system
Reset Operation
If a voltage spike or static discharge blanks out the display or
causes erratic thermostat operation you can reset the thermostat
by pressing , and TIME at the same time. This also
resets the factory defaults. If the thermostat has power, has been
reset and still does not function correctly contact your heating/
cooling service person or place of purchase.
W905
W906 - clip for 5/1/1 day programming
RH
24 VAC 120 VAC
Hot
Neutral
THERMOSTAT
SYSTEM
G W
Figure 2. Typical wiring diagram for
heat only, 3-wire, single transformer systems
TRANSFORMER
Heating
System
Fan
Relay
Y RC
JUMPER
WIRE
O B
For 2-wire Heat only,
attach to RH and W
NOTE
RH Y
24 VAC 120 VAC
Hot
Neutral
TRANSFORMER
THERMOSTAT
SYSTEM
G W
Figure 3. Typical wiring diagram for
cool only, 3-wire, single transformer systems
Cooling
System
Fan
Relay
RC O B
JUMPER
WIRE
RH Y
24 VAC 120 VAC
Hot
Neutral
THERMOSTAT
SYSTEM
G W
Figure 4. Typical wiring diagram for
heat/cool, 4-wire, single transformer systems
TRANSFORMER
Heating
System
Fan
Relay
Cooling
System
RC
JUMPER
WIRE
O B
REDjumper wire (provided with thermostat) must be
connected between thermostatRH andRC terminals
for proper thermostat operation with this system.
NOTE
RH Y
24 VAC 120 VAC
Hot
Neutral
THERMOSTAT
SYSTEM
G W
Figure 5. Typical wiring diagram for
heat/cool, 5-wire, two-transformer systems
HEATING
TRANSFORMER
Heating
System
Fan
Relay
Cooling
System
RC
24 VAC 120 VAC
Hot
Neutral
COOLING TRANSFORMER
O B
RH Y
24 VAC 120 VAC
Hot
Neutral
THERMOSTAT
SYSTEM
G W
Figure 6. Typical wiring diagram for heat pump
with reversing valve energized in COOL
TRANSFORMER
Reversing
Valve*
RC O B
JUMPER
WIRE
Compressor
Contactor
JUMPER
WIRE
* Reversing valve is energized when the
system switch is in the COOL position
Fan
Relay
RH Y
24 VAC 120 VAC
Hot
Neutral
THERMOSTAT
SYSTEM
G W
Figure 7. Typical wiring diagram for heat pump
with reversing valve energized in HEAT
TRANSFORMER
Reversing
Valve*
RC O B
JUMPER
WIRE
Compressor
Contactor
JUMPER
WIRE
* Reversing valve is energized when the
system switch is in the HEAT position
Fan
Relay
Figure 1
162
TECHNICAL HELP