The thermostat uses 1 wire to control each of your hvac system s primary functions such as heating cooling fan etc.
Thermostat wiring heat pump gas furnace.
Heating only thermostat wiring diagrams if you only have a furnace such as a gas furnace oil furnace electric furnace or a boiler.
Therefore you will use the following color code for simple thermostat wiring.
S indoor and outdoor wired sensors.
For example if the red wire is connected to w on the thermostat the furnace should turn on.
Both the furnace control board and the thermostat will usually have the same terminal letters.
Before uninstalling the old thermostat take a picture of the wiring with your cell phone before removing the wires.
This way you have a reference.
It corresponds to the chart below to explain the thermostat terminal functions.
Y compressor stage 1 cooling y2 compressor stage 2 cooling g fan.
Terminal r or terminal rh for the red wire.
See the diagram below for what each wire controls on your system.
My paperback and e book.
When the red wire is disconnected from w the furnace should turn off.