White Rodgers Thermostat 1F78 - Manual (Page 3)

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NOTE
To prevent static discharge problems, touch side of thermostat
to release static build-up before touching any keys.
5
CHECK THERMOSTAT OPERATION
4
MOUNTING AND WIRING
CONTINUED FROM SECOND PAGE
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
RED jumper wire (provided with thermostat) must be
connected between thermostat
RH and RC 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
If at any time during testing your system does not operate properly,
contact a qualified service person.
Fan Operation
If your system does not have a G terminal connection, skip to
Heating System.
1. Turn on power to the system.
2. Move FAN switch to
ON position. The blower should begin to
operate.
3. Move FAN switch to AUTO position. The blower should stop im-
mediately.
Cooling System
This thermostat has a time delay between cooling cycles to allow the
head pressure in the compressor to stabilize. If the temperature is
adjusted to call for cool within 5 minutes of the last cycle the snow-
flake icon will blink indicating the thermostat is locked out. After 3 to
5 minutes, the compressor will start and the snowflake icon will stop
flashing. This helps prevent the compressor from cycling too quickly
and is normal operation for the thermostat.
1. Move SYSTEM switch to COOL position.
2. Press to adjust thermostat setting below room temperature.
The blower should come on immediately on high speed, followed
by cold air circulation
3. Press to adjust temperature setting above room temperature.
The cooling system should stop operating.
Heating System
1. Move SYSTEM switch to HEAT position. If the heating system
has a standing pilot, be sure to light it.
2. Press to adjust thermostat setting above room temperature.
The heating system should begin to operate.
3. Press to adjust temperature setting below room temperature.
The heating system should stop operating.
CAUTION !
To prevent compressor and/or property damage, if the
outdoor temperature is below 50°F, DO NOT operate the
cooling system.