Terminal Designations
Wiring Notes
Common wire
The C (common wire) is optional when the thermostat is
powered by batteries.
Wire Specifications
Use 18- to 22-gauge thermostat wire. Shielded wire is not required.
Notes:
In many heat pump systems without emergency heat relay, a jumper can be
installed between E and W2 to the turn thermostat into a single stage control
for Emergency Heat Operation.
Installation Tip: Do not overtighten terminal block screws, as this
can damage the terminal block. A damaged terminal block can
keep the thermostat from fitting on the subbase correctly or cause
system operation issues. Max Torque = 6in/lbs.
Power supply
Factory-installed jumper. Remove only when installing on
2-transformer systems.
Use either O or B terminals for reversing valve.
Optional 24 VAC commom connection when thermostat is used in
battery power mode.
Wiring
Wiring Diagrams
Wiring Diagrams
Wiring Diagrams
5
6
7
8
This thermostat is shipped from the factory to operate a conventional heating
and cooling system. This thermostat may also be configured for a heat pump
system. See the “heat pump” configuration step on page 14 of this manual to
configure the thermostat for heat pump applications.
Terminal
2 Heat 2 Cool
Conventional System
2 Heat 1 Cool
Heat Pump System
3 Heat 2 Cool
Heat Pump System
RC
24 VAC power (Cooling)
24 VAC power (Cooling)
24 VAC power (Cooling)
RH
24 VAC power (Heating)
24 VAC power (Heating)
24 VAC power (Heating)
C
24 VAC common
24 VAC common
24 VAC common
B
Reversing valve / configurable terminal Reversing valve / configurable terminal Reversing valve / configurable terminal
O
Reversing valve / configurable terminal Reversing valve / configurable terminal Reversing valve / configurable terminal
G
Fan relay
Fan relay
Fan relay
W/E
First stage of heat
Emergency Heat
First stage of auxiliary heat
Y
First stage of cool
First stage of heat & cool
First stage of heat & cool
Y2
Second stage of cool
N/A
Second stage of heat & cool
W2
Second stage of heat
Auxiliary heat
Second stage of auxiliary heat
Typical 2H/2C System: 1 Transformer
HEAT RELAY
HEAT RELAY 2
COMPRESSOR
RELAY
COMPRESSOR
RELAY 2
FAN RELAY
(HOT)
Typical Cool-Only System With Fan
FAN RELAY
COMPRESSOR
RELAY
(HOT)
REMOVE JUMPER
HEAT RELAY
HEAT RELAY 2
FAN RELAY
COMPRESSOR
RELAY
COMPRESSOR
RELAY 2
Typical 3H/2C or 2H/1C Heat Pump System
COMPRESSOR
RELAY
COMPRESSOR
RELAY 2
AUXILIARY
HEAT RELAY
EMERGENCY
HEAT RELAY
COOL REVERSING
VALVE
HEAT REVERSING
VALVE
FAN RELAY
(HOT)
(HOT)
Typical 2H/2C System: 2 Transformers
Typical Heat Only System With Fan
HEAT RELAY
FAN RELAY
(HOT)
Note:
In many systems with no emergency heat relay a jumper can be installed between
E and W2
