Installation Guide
4
Wiring
1 Loosen screw terminals,insert
wires into terminal block,then re-
tighten screws.
2 Push excess wire back into the
wall opening.Keep wires in shaded
area as shown at left.
3 Plug the wall opening with non-
flammable insulation to prevent
drafts from affecting thermostat
operation.
Terminal Designations
WWHeat relay.
YYCompressor contactor.
GGFan relay.
OOHeat pump changeover valve ener-
gized in cooling.
RRccCooling power.Connect to
secondary side of cooling
system transformer.
RRHeating power.Connect to
secondary side of heating
system transformer.
BBHeat pump changeover valve ener-
gized in heating.
CCCommon wire from secondary side
of cooling system transformer.
Terminal
block
NOTES
R & Rc terminals
In single-transformer system, leave metal
jumper in place between R &Rc. Remove
metal jumper if two-transformer system.
Heat pump systems
If wiring to a heat pump, use a small piece of
wire (not supplied) to connect terminals W
and Y.
C terminal
The C (common wire) terminal is optional
when thermostat is powered by batteries.
Wire specifications
Use 18- to 22-gauge thermostat wire.
Shielded cable is not required.
Keep wires in this
shaded area
CAUTION: ELECTRICAL HAZARD. Can cause electrical shock or equipment damage.
Disconnect power before wiring.
Wiring
Jumper