Lowe's Home Improvement

Install a Programmable Thermostat

Heating and cooling your home can be expensive, but a programmable thermostat can help you control the energy costs.

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Programmable Thermostat Considerations

Programmable Thermostat.

A programmable thermostat lets you customize the heating and cooling of your home to your needs, ensuring the heat and air conditioning aren't running when you don't need them. You can set your system for one temperature when you're at home, and another when you're away.

Different programming options are available, and you can control some thermostats remotely over Wi-Fi. You can also find thermostats that create schedules and automatically adjust when you're away. To learn more about selecting a programmable thermostat, see Selecting the Right Thermostat for Your Home.

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Follow the manufacturer's instructions for installation and safety. Check to see if you need a permit. Observe applicable building and electrical codes. Contact a licensed electrician if you have any doubts or questions about the connections, or if your home's wiring doesn't appear compatible with the changes you're making.

How to Install or Replace a Programmable Thermostat

Make sure the thermostat is compatible with your heating and cooling system — installation might differ by model and type of system in your home. Follow local and national codes for electrical connections.

Step 1

Turn off the old unit.

Step 2

Turn off the power to your heating and cooling system at the main fuse or circuit box.

Step 3

Thermostat Wiring Connections.

Remove the existing thermostat, but leave the wall plate in place for now so you can note how the wires are connected. Test the wires with a circuit tester to verify the power is off.

Watch our related DIY Basics videos:

How Do I Strip a Wire?

How Do I Connect Two Wires?

What's In My Breaker Box?


Older thermostats with glass tubes contain mercury. Use caution when handling and check with your local recycling company for disposal instructions.

Step 4

Thermostat Wiring with Labels.

Label each wire on your existing system with the letter designation of the terminal it's connected to. Ignore the wire color — use only letters to identify the wires. Your new thermostat may come with pre-printed labels for this step.

Step 5

Taking a Picture of the Thermostat Wiring.

Take a picture of the existing connections so you'll have a visual reference later if you need it.

Step 6

Removing the Old Thermostat.

Disconnect the wires and remove the existing wall plate.

Good to Know

Secure the wires to keep them from falling back into the wall. You can wrap them around a pencil or tape them to the wall.

Step 7

Removing Wall Anchors.

Depending on the shape and size of your new thermostat, you may need to remove the old wall anchors and patch the holes. See Removing Unwanted Wall Anchors for instructions.

Step 8

Installing the New Thermostat.

Install the new wall plate. Use a level and mark the location for the mounting holes. Drill the holes and, if needed, insert drywall anchors. Feed the wires through the wall plate and fasten the plate to the wall. Secure the wires so they don't fall back into the wall.

Step 9

Connecting the New Thermostat.

Follow the instructions that came with your new unit and use the labels on the wires to determine the proper connections to the terminals. Insert the wires into the corresponding terminals on the thermostat and tighten the terminal screws. There may be a metal jumper connecting the R and Rc terminals on the new thermostat. The manual will direct you whether to leave it in place or remove it. Wi-Fi thermostats may require a C wire. If you don't have a C wire, consult the manual for options.

Step 10

Install batteries as needed.

Step 11

New Thermostat Installed.

Mount the new thermostat onto the wall plate.

Step 12

Restore power and set up the new thermostat according to the manufacturer's instructions.