Thermostat Wiring For Furnace And Ac

Always refer to your thermostat or equipment installation guides to verify proper wiring.

Thermostat wiring for furnace and ac.

Flip the furnace ac breaker to the off position. Sometimes depending on the thermostat and the manufacturer the thermostat can be a dual heat pump thermostat. W terminal to the white wire. Label where the wires are connected on the thermostat.

The thermostat is likely a digital thermostat that requires the c wire or the common wire to provide power for the thermostat. A thermostat with five wires typically controls an air conditioner with a heating system. Y terminal to the yellow wire. The white wire connects to terminal w in industry standard thermostats.

The yellow wires connect to the y terminals on your thermostat. The white wire underneath your thermostat connects to your heating system. Check to see if they match the industry standard listed above. The yellow wires terminate at your compressor contactor via an air handler.

They control your air conditioning system. In the most basic system this functionality is provided by use of a fan center relay and the low voltage wiring to the thermostat now will require a minimum of three wires for heat only. The two 24 volt wires go to the r terminal and c terminal inside the thermostat. This diagram is to be used as reference for the low voltage control wiring of your heating and ac system.

Notesome ac systems will have a blue wire with a pink stripe in place of the yellow or y wire. G terminal to the green wire. That will power the relay contactor or complete the circuit in the circuit board. Thermostats use 24 volts ac from a transformer to control a furnace.

Furnace 24 volt transformer. Once your c wire is ready follow these steps to install your new thermostat. Turn off your existing thermostat. C terminal to the blue wire.

R terminal for the red wire. Additionally it will require a different thermostat and different wiring than an air conditioner. It terminates at your air handler or furnace. This function allows you to circulate the air in the house by using the fan in the furnace without heating or cooling the air moving through the system.

The transformer steps down 120 volts to the 24 volts the thermostat needs and sends out the 24 volts on two wires. Breakdown of colors and terminals thermostat wiring diagram for ac unit. The yellow wires underneath your thermostat connect to your compressor.