Thermostat Terminals and Connections

Thermostat Terminals and Connections

 

Common Wiring Terminals / Connections for Thermostats

 

Terminal Description
   
RH

24 Volt Hot for Heating

RC 24 Volt Hot for Cooling
C 24 Volt Common
G Fan
Y or Y1 Compressor, First Stage Cool
Y2 Second Stage Cool
W or W1 First Stage Heat
W2 Second Stage Heat
O Heat Pump Reversing Valve Cooling
B

Heat Pump Reversing Valve Heating

 

Notes: 

  • C connection is often ommitted by builders but is required for most automated thermostats to power the thermostat.  There are ways around this requirement such as 5-4 wire adapter kits, or in the case of some brands like NEST they use an on board battery that is charged during use and powers the thermostat.
  • RH and RC may be have a jumper wire between them in some installations
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