Honeywell Round - Wiring; Terminal Designations; Wiring Configurations Overview

8
Wiring
Terminal Designations
L Heat pump system monitor K Optional wire saver module
C Common wire from secondary side of
cooling transformer, if 2 transformers
G Fan relay
W2
(AUX)
2nd stage heat relay (heat pump
auxiliary, emergency heat)
Y2 2nd stage compressor contactor
W
(O/B)
1st stage heat relay (changeover valve
for heat pumps)
Y 1st stage compressor contactor
U1 Universal terminal for indoor air quality
products (humidifier, dehumidifier,
ventilator)
R Heating power. Connect to
secondary side of heating
system transformer
U2 Universal terminal for indoor air quality
products (humidifier, dehumidifier,
ventilator)
Rc Cooling power. Connect to
secondary side of cooling
system transformer
Wiring Configurations
Two stage furnace and air-conditioning
C Common wire (optional)
W2 Heat relay (stage 2)
W Heat relay
G Fan relay
Y2 Compressor contactor (stage 2)
Y Compressor contactor (stage 1)
R Power
Notes
• Thermostat C wire
is optional for this
application. C wire
required if Homekit
is used.
• Set the R Jumper
Switch on the wall
plate to R