CONFIGURATION AND
TYPICAL WIRING DIAGRAMS
1E78-151
Mounting
Hole
Reset Operation
If a voltage spike or static discharge blanks out the display or
causes erratic thermostat operation you can reset the thermostat
W906
W905
W904
W903
by pressing
,
and TIME at the same time. This also
RC
G
RH
W
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.
Y
O
B
ELEC GAS
Elec/Gas
Switch
Mounting
Hole
Back of
Thermostat Body
Base
W903 - clip to disable EMR feature
W904 - clip for Celcius display
W905 - clip for hydronic system
W906 - clip for 5/1/1 day programming
Figure 1
JUMPER
WIRE
THERMOSTAT
B
O
Y
G
W
RC
RH
THERMOSTAT
SYSTEM
Hot
B
O
Y
G
W
RC
RH
SYSTEM
Cooling
System Relay System
Fan
Heating
2
2
4 VAC
120 VAC
Neutral
Fan
Relay
Heating
System
Hot
HEATING
TRANSFORMER
2
4 VAC
120 VAC
Neutral
NOTE
For 2-wire Heat only,
attach to RH and W
Hot
TRANSFORMER
4 VAC
120 VAC
Neutral
Figure 2. Typical wiring diagram for
COOLING TRANSFORMER
heat only, 3-wire, single transformer systems
Figure 5. Typical wiring diagram for
heat/cool, 5-wire, two-transformer systems
JUMPER
WIRE
THERMOSTAT
B
O
Y
G
W
RC
RH
SYSTEM
JUMPER
WIRE
JUMPER
WIRE
Cooling
System Relay
Fan
THERMOSTAT
SYSTEM
B
O
Y
G
W
RC RH
Hot
2
4 VAC
120 VAC
Neutral
Reversing Compressor Fan
Valve* Contactor Relay
Hot
TRANSFORMER
2
4 VAC
120 VAC
Figure 3. Typical wiring diagram for
* Reversing valve is energized when the
system switch is in the COOL position
Neutral
TRANSFORMER
cool only, 3-wire, single transformer systems
Figure 6. Typical wiring diagram for heat pump
with reversing valve energized in COOL
NOTE
RED jumper wire (provided with thermostat) must be
connected between thermostat RH and RC terminals
for proper thermostat operation with this system.
JUMPER
WIRE
JUMPER
WIRE
JUMPER
WIRE
THERMOSTAT
SYSTEM
THERMOSTAT
SYSTEM
B
O
Y
G
W
RC RH
B
O
Y
G
W
RC RH
Cooling
System Relay
Fan
Heating
System
Reversing Compressor Fan
Valve* Contactor Relay
Hot
Hot
2
4 VAC
120 VAC
2
4 VAC
120 VAC
*
Reversing valve is energized when the
system switch is in the HEAT position
Neutral
TRANSFORMER
Neutral
TRANSFORMER
Figure 7. Typical wiring diagram for heat pump
with reversing valve energized in HEAT
Figure 4. Typical wiring diagram for
heat/cool, 4-wire, single transformer systems
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