Thermostat Wiring For Furnace And Ac

A thermostat with five wires typically controls an air conditioner with a heating system.

Thermostat wiring for furnace and ac.

That will power the relay contactor or complete the circuit in the circuit board. 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 two 24 volt wires go to the r terminal and c terminal inside the thermostat. The thermostat is likely a digital thermostat that requires the c wire or the common wire to provide power for the thermostat.

Always refer to your thermostat or equipment installation guides to verify proper wiring. Check to see if they match the industry standard listed above. The yellow wires connect to the y terminals on your thermostat. R terminal for the red wire.

Flip the furnace ac breaker to the off position. C terminal to the blue wire. Label where the wires are connected on the thermostat. Thermostats use 24 volts ac from a transformer to control a furnace.

The white wire underneath your thermostat connects to your heating system. The transformer steps down 120 volts to the 24 volts the thermostat needs and sends out the 24 volts on two wires. Notesome ac systems will have a blue wire with a pink stripe in place of the yellow or y wire. The yellow wires terminate at your compressor contactor via an air handler.

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. Y terminal to the yellow wire. The heating system will likely be a gas or electric furnace. Additionally it will require a different thermostat and different wiring than an air conditioner.

The white wire connects to terminal w in industry standard thermostats. Red wire for air conditioner control power hot 1 the r terminal is the 24 volt hot feed from the control step down transformer. Once your c wire is ready follow these steps to install your new thermostat. Or it can be used for an air conditioner and gas furnace system depending on how the thermostat is wired.

The yellow wires underneath your thermostat connect to your compressor. W terminal to the white wire. Turn off your existing thermostat. They control your air conditioning system.

G terminal to the green wire. Furnace 24 volt transformer. Breakdown of colors and terminals thermostat wiring diagram for ac unit.