Robertshaw RS8110 Installation Manual page 12

WIRING
Terminal Designations
W Heat relay
G Fan relay
Y Compressor relay
O Heat pump reversing valve energized in cooling
RC 24 volt cooling transformer
RH/R 24 volt heating transformer OR 24 volt power
terminal if a common wire is present
B Heat pump reversing valve energized in heating
C 24 volt common terminal
Notes:
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 Auxiliary 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).
10
Wire specifications
Use 18- to 22-gauge thermostat wire. Shielded wire
is not required.
Common Wire
The C (common wire) is optional when the thermostat
is powered by batteries.