Install Instructions

Terminal Designations
Wiring Notes
C 24 VAC Common Wire
O Heat pump reversing valve energizedin cooling
B Heat pump reversing valve energizedin heating
W Heat relay
RH 24 VAC power for heating
RC 24 VAC power for cooling
G Fan relay
Y Compressor relay
RH & RC Terminals
In a single-transformer system, leave the metal jumper in
place between the RH and RC. Remove the metal jumper in
two-transformer systems.
Heat Pump Systems (With NO Auxilary or Emergency Heat)
If wiring to a heat pump, use a small piece of wire (not supplied)
to connect terminals W (Heat relay) & Y (Compressor relay).
Common wire
The C (common wire) is optional when the thermostat is
powered by batteries.
Wire Specications
Use 18- to 22-gauge thermostat wire. Shielded wire is not required.
Installation Tip: Do not overtighten terminal block screws, as this
can damage the terminal block. A damaged terminal block can
keep the thermostat from tting on the subbase correctly or cause
system operation issues. Max Torque = 6in/lbs.
Typical 1H/1C System: 1 Transformer
COMPRESSOR
RELAY
HEAT RELAY
FAN RELAY
HOT
Typical 1 H/1 C Heat Pump System
COOL REVERSING
VALVE
HEAT REVERSING
VALVE
FAN RELAY
HOT
COMPRESSOR
RELAY
Power supply
Factory-installed jumper. Remove only when installing on
2-transformer systems.
Use either O or B terminals for reversing valve.
Use a small piece of wire (not supplied) to connect W and Y terminals. ONLY
for a heat pump system without AUX or EMERGENCY heat
Set fan operation switch to electric for heat pump systems.
Typical Heat-Only System With Fan
HEAT RELAY
FAN RELAY
HOT
Typical 1H/1C System: 2 Transformers
COMPRESSOR
RELAY
REMOVE JUMPER
HEAT RELAY
FAN RELAY
HOT
HOT
Typical Cool-Only System
COMPRESSOR
RELAY
FAN RELAY
HOT
Typical Heat-Only System
HEAT RELAY
HOT
Wiring Wiring Diagrams
Wiring Diagrams
Wiring Diagrams
5 6
7 8