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Your Complete Guide to Thermostat Wire Colors

Your Complete Guide to Thermostat Wire Colors

Installing a thermostat correctly is crucial to protecting the safety of your home and your family. Improper installation could result in electrocutions, system malfunctions, and uncomfortable temperatures. To help you install your thermostat correctly, we have created an outline of thermostat wire colors. Each of the wires is responsible for a different function on your thermostat.

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Every Wire Color You’ll Find on a Thermostat

Whether it’s the red wires or the yellow wires on your thermostat, you should always know what each wire is and what purpose it serves before attempting any repairs or installations. This simple step will prevent you from getting your wires crossed.

White Wire

Running from the thermostat to the heater, the white wire controls the entire heating system in your home. Your thermostat may contain more than one white wire if your heating system has more than one heating stage. If your heating system only has one heating stage, the thermostat will only contain one wire.

Yellow Wire

The yellow wires on your thermostat join the device to the compressor so you can manage the air conditioning system in your home.

Green Wire

The green wire connects the thermostat to the fan of your heating system.

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Orange Wire

The orange wire runs from the thermostat to the heat pump. If your home doesn’t have a heat pump, the thermostat either won’t contain this wire color or may have it but won’t use it.

Red Wire

The red wires provide the thermostat with power.

Blue Or C Wire

The blue wire—also called the C, or “common,” wire—is required to power any thermostat and ensure proper system function. Your HVAC system and thermostat configuration will determine what color the C wire will be. The C wire in homes with a heat pump is always blue. In other cases, it could be one of various wire colors.

Upgrade Your Thermostat in 5 Easy Steps

Upgrade Your Thermostat in 5 Easy Steps

Follow these five steps for a stress-free thermostat installation process.

  1. Remove the old thermostat: Take off your thermostat’s cover plate so you have a clear view of all the wires connected to the back. If the cover plate is held down by screws, you’ll need to remove them with a screwdriver.
  2. List the connections: Take note of how many wires your thermostat has and the color of each so you know what each one controls. This step will make the installation process a piece of cake.
  3. Remove the old backboard: Disconnect your furnace’s power supply along with the thermostat wires. If the new thermostat doesn’t align with the size of your current backboard, you’ll need to replace it with a new one.
  4. Reconnect all the wires: Once you’ve installed the new backboard (if needed), it’s time to connect the wires to the new thermostat. Don’t let this step intimidate you. If you made note of where each wire color goes and what it does, it should be a breeze.
  5. Install the thermostat on the backboard: The only things left for you to do are to secure the new thermostat onto the backboard, test each thermostat function to ensure the wires were connected properly, and enjoy prime temperature control.

How to Inspect & Replace the Thermocouple in Your Furnace

HVAC Repair & Installation Services

If you aren’t confident in your ability to install a new programmable thermostat, contact the professionals at Horizon. Our team of HVAC technicians and electricians in Charlotte, NC will help you install a new thermostat in your house. With over 30 years of industry experience, our certified technicians could perform a programmable thermostat installation with their eyes closed. In addition, our team of professionals offer HVAC services for homeowners in Pennsylvania, New Jersey, Maryland, Delaware, and North Carolina.

We offer a variety of HVAC services such as furnace repair, heat pump installation, air conditioning replacement, furnace installation and boiler maintenance. Our technicians provide innovative air conditioning and heating services for homes in your area to ensure you are comfortable throughout the winter and summer seasons. Whether you need help installing a thermostat or fixing a malfunctioning HVAC system, book an appointment with our team to receive support.


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