How do I wire my RTH6500WF Smart Series Programmable Thermostat?

The thermostat uses 1 wire to control each of your HVAC system’s primary functions, such as heating, cooling, fan, etc. See the diagram below for what each wire controls on your system:

Y – Compressor Stage 1 (Cooling)
Y2 – Compressor Stage 2 (Cooling)
G – Fan
C – Common
L/A – A – Input for heat pump fault
W -O/B – Heat Stage 1 (Heating) / Reversing valve for Heat Pump systems
W2 -Aux/E – Heat Stage 2 (Heating) / Backup Heat
R – 24vac (Heating transformer)
Rc – 24vac (Cooling transformer)

at its most basic, your thermostat connects terminals via internal relays to send power to these different wires to control your HVAC system. For instance, for a gas furnace to turn on the heat, the thermostat internally connects the R terminal (power) to the W terminal (heat stage 1) to turn on the furnace.

Look at the list of wiring configurations by system type below. Your wiring will match one of the options below. If you do not see your wiring listed, we recommend using our on-line compatibility checker.

1H/1C Conventional Gas/Oil/Electric Forced Air System (1 transformer):
R wire - Power [R+Rc joined by jumper]
Y wire - Compressor contactor
C wire - 24VAC common
W wire - Heat relay
G wire - Fan relay

1H/1C Conventional Gas/Oil/Electric Forced Air System (2 transformers):
R wire - Power (heating transformer)
Rc wire - Power (cooling transformer)
Y wire - Compressor contactor
C wire - 24 VAC common from cooling transformer
W wire - Heat relay
G wire - Fan relay

2H/2C Conventional Gas/Oil/Electric Forced Air System (1 transformer):
R wire - Power [R+Rc joined by jumper]
Y wire - Compressor contactor (stage 1)
C wire - 24VAC common W Heat relay (stage 1)
G wire - Fan relay
W2 wire - Heat relay (stage 2)
Y2 wire - Compressor contactor (stage 2)

Hot Water / Steam / or Radiant in-floor Heat: 
R wire - Power [R+Rc joined by jumper]
W wire - Heat Relay
C wire - 24VAC common

Heat-only System with Fan:
R wire - Power [R+Rc joined by jumper]
C wire - 24VAC common
W wire - Heat relay
G wire - Fan relay

Cool-only System with Fan:
R wire - Power [R+Rc joined by jumper]
Y wire - Compressor contactor
C wire - 24VAC common
G wire - Fan relay

1H/1C Heat Pump System:
R wire - Power [R+Rc joined by jumper]
Y wire - Compressor contactor
C wire - 24VAC common
O/B wire - Changeover valve
G wire - Fan relay

2H/1C Heat Pump System: NOTE: If dual fuel, TH6320WF (Trade FocusPRO WiFi 6000 only)
R wire - Power [R+Rc joined by jumper]
Y wire - Compressor contactor
C wire - 24VAC common
O/B wire - Changeover valve
G wire - Fan relay Aux Auxiliary heat*
E wire - Emergency heat relay
L wire - Heat pump fault input

2H/2C Heat Pump System:
R wire - Power [R+Rc joined by jumper]
Y wire - Compressor contactor (stage 1)
C wire - 24VAC common
O/B wire - Changeover valve
G wire - Fan relay
Y2 wire - Compressor contactor (stage 2)
L wire - Heat pump fault input

3H/2C Heat Pump System: NOTE: If dual fuel, TH6320WF (Trade FocusPRO WiFi 6000 only)
R wire - Power [R+Rc joined by jumper]
Y wire - Compressor contactor (stage 1)
C wire - 24VAC common
O/B wire - Changeover valve
G wire - Fan relay
Aux wire - Auxiliary heat*
E wire - Emergency heat relay*
Y2 wire - Compressor contactor (stage 2)
L wire - Heat pump fault input