The most basic thermostat has 2 wires; usually a red and a white wire. Two wire thermostat wiring is used for furnaces only and usually doesnt need a “C” or “Common” wire. Thats why we only need two wires: Red wire for power (24h).

How many thermostat wires do I need?

Most systems today require a minimum of 5 wires when both heating and air conditioning equipment is included in the system. Our pro recommendation is to use 18/8 wire.

Why does my thermostat have 4 wires?

The concept is that when you adjust your thermostat its like flipping a switch, and you are providing power to the your HVAC system to work, its just that in a typical 4 wire thermostat the thermostat decides where to route the power to turn on your HVAC system to make it heat, cool or run the fan.

How do I wire a 2 wire thermostat?

Strip the red and white wires back about 1/4 inch at both the thermostat and the furnace ends. Connect the white wire to the W terminal on the furnace and thermostat. Repeat this for the red wire, connecting it to the R terminal on both the furnace and thermostat.