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White Rodgers 1F78-151 White-Rodgers 70 Series Single Stage Thermostat Installation Instruction

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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
5
 CHECK THERMOSTAT OPERATION
NOTE
To prevent static discharge problems, touch side of thermo-
stat to release static build-up before touching any keys. 
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
To  prevent  compressor  and/or  property  damage,  if  the 
outdoor temperature  is  below  50°F,  DO NOT  operate  the 
cooling system.
CAUTION
!
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 
snowflake icon will blink indicating the thermostat is locked out. Af-
ter 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  tempera-
ture. The blower should come on immediately on high speed, 
followed by cold air circulation
3.  Press 
 to adjust temperature setting above room tempera-
ture. 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 tempera-
ture. The heating system should begin to operate.
3.  Press 
 to adjust temperature setting below room tempera-
ture. The heating system should stop operating.