Thermostat wiring consists of wires that connect the transformer to the system relays. When you move the lever on the thermostat to turn up the heat, this rotates the thermometer coil and mercury switch, tipping them to the left.

How do thermostat wires work?

Here is the industry standard thermostat wire color code used for most systems:White. The white wire connects to your heat.Yellow. The yellow wire connects to your compressor.Green. The green wire connects to the fan.Orange. This wire connects to your heat pump (if applicable).Red (C). Red (H). Blue.

What are the two wires in a thermostat?

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).

Where does thermostat get power?

Most room thermostats on heating and cooling systems get their 24V DC electrical power from a low voltage transformer that is usually found at the boiler or furnace.

Can you replace a 2 wire thermostat with a 4 wire thermostat?

Yes, you can connect a four wire thermostat to this setup. Connect the white wires in the same manner as the black wires are connected.

How do you test thermostat wires?

1:395:57How to Test a Thermostat with a Multimeter! - YouTubeYouTube