What are the 3 wires in a thermostat?

3 Wire Thermostat Wiring (Boilers, Heaters)

• Red wire for power (24V).
• White wire for heating (connected to W or W1 terminal).
• Green wire as a repurposed C wire.

What are the 4 wires on a thermostat?

This is a popular configuration for a battery-powered thermostat or a digital thermostat that solely regulates heat. The standard configuration consists of 24-volt hot (red), 24-volt common (blue), heat (white), and a fan (green).

Where do the colored wires go on a thermostat?

The yellow wires underneath your thermostat connect to your compressor. They control your air conditioning system. The yellow wires terminate at your compressor contactor via an air handler. The yellow wires connect to the Y terminals on your thermostat.

How do you wire up a thermostat?

Here’s how to wire a thermostat using the color code and, FYI, each terminal’s purpose.

1. Attach the red wire to the R terminal (Call for heating and/or cooling).
2. Attach the green wire to the G terminal (Fan).
3. Attach the white wire to the W terminal (Heat).
4. Attach the yellow wire to the Y terminal (AC).

What color is C wire?

Blue wires
Blue wires are also called “C” wires because they are the Common wire. C wires are necessary for any “smart” thermostat that needs to be connected to a power source 24/7, regardless of your heat pump type.

What is common wire on thermostat?

A C-wire, or a common wire, runs from your low voltage heating system (24v) and carries continuous power to your thermostat. In today’s electric market, most newer heating and cooling systems have C-wires, which guarantees compatibility for the installation of all smart thermostats.

What is b wire on thermostat?

The O wire reverses the valve from heating to cooling, and the B wire switches the valve from cooling to heating.

How do I install a new thermostat?

How to Replace a Thermostat

1. Step 1: Turn Off the Unit and the Power. Turn off the old unit.
2. Step 2: Remove the Thermostat.
3. Step 3: Label the Wires.
4. Step 4: Take a Picture.
5. Step 5: Disconnect the Wires.
6. Step 6: Remove the Old Wall Anchors.
7. Step 7: Install the New Wall Plate.
8. Step 8: Connect the Wires.

What are the 5 thermostat wires?

Here are common uses for wire colors:

• Blue or Black – C – Common wire, may be unused by your existing thermostat.
• Red – R – 24VAC power from the furnace’s transformer.
• Red – Rc – 24VAC (dedicated to heat call)
• Red – Rc – 24VAC (dedicated to cooling call)
• Green – G – Fan.
• White – W – Heat.
• Yellow – Y – Air conditioner.