What do the Terminal Markings of HVAC Controller Represent?

The following table summarises the terminals of the HVAC Controller along with their common variants:

Label(s)DescriptionCommon Variants
LTerminal for the live wire to power the controller
NTerminal for the neutral wire connection
RCPower wire from the cooling equipmentR
RHPower wire from the heating equipmentR
CommonAllows the continuous flow of power that the thermostat requires to operateC
W1Controls your heating systemW
W2Controls the second stage of your heating systemW
Y1Controls your compressorY
Y2Controls the second stage of your compressorY
GL, GM, GHControls the multi-speed fan, where GL is low speed, GM is medium speed, and GH is high speed.G1, G2, G3
O/BUtilised for heat pump systems to tell the compressor to switch between heating and cooling.