Emerson 850 Thermostat User Manual


 
www.white-rodgers.com
MOUNTING AND WIRING
CONTINUED FROM SECOND PAGE
4
The 24 Volt neutral connection to terminal C on the
thermostat is not required if the batteries are replaced
once a year with fresh AA Energizer
®
alkaline batteries.
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
YC
RC
JUMPER
WIRE
OB
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
RCOB
C
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
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
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
OBC
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*
RCOBC
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*
RCO
B
C
JUMPER
WIRE
Compressor
Contactor
JUMPER
WIRE
* Reversing valve is energized when the
system switch is in the HEAT position
Fan
Relay