Tools and Materials

Tools

Materials

Note

Some tools may require batteries. Check the manufacturer’s specifications to see if they’re included.

Product costs, availability and item numbers may vary online or by market.

Thermostat Considerations

Photo of a programmable thermostat package.

A programmable thermostat lets you customize the heating and cooling of your home based on 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. There are also smart thermostats that can be controlled remotely over Wi-Fi. Some thermostats create schedules and automatically adjust to your needs when you’re away.

To learn more about selecting a programmable thermostat, see Selecting the Right Thermostat for Your Home.

Shop Programmable Thermostats Shop Thermostats Shop Smart Home Products

Caution

Follow the manufacturer’s instructions for how to change a thermostat safely. Check to see if you need a permit and observe the 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.

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

How to Replace a Thermostat With a Programmable Model

Before replacing your thermostat, make sure the new device is compatible with your heating and cooling system. Your thermostat installation might differ depending on the model and type of system in your home.

Instructions

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 instruct 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, as most units without a C wire require professional smart thermostat installation.

How to Install a Smart Thermostat

A silver Google Nest thermostat with a black display indicating 70 degrees Fahrenheit.

Whether you need tips for a Google Nest thermostat installation or installation of a smart thermostat from Honeywell Home, ecobee or another manufacturer, the steps will be similar. Many are the same as those for installing a standard thermostat, but you’ll set up a smart thermostat differently after the installation. We’ll outline general smart thermostat installation steps below, but always follow the instructions in the manual or app for your model since installation may vary and the programming and learning functions will require different setups.

In most cases, installing a smart thermostat is a relatively simple project that someone with a bit of do-it-yourself experience can complete in about 30 to 60 minutes.

Good to Know

If you don’t have time to install the device yourself or would simply prefer to have a professional handle the work, see how you can let us install your smart home devices. Then shop our installation-compatible smart thermostats.

Before Beginning Installation

These smart devices are compatible with a wide range of heating, ventilation and air conditioning (HVAC) systems, but some systems will not work with these devices. Your product information should help you determine if your system is compatible, but in general, common incompatible systems include:

High-Voltage Systems: A high-voltage system will often include two or four thick wires rather than several thin wires. You may see twist-on wire connectors and a label on the existing thermostat indicating high voltage or specifying 110 VAC (volts alternating current) or higher.
Millivolt Systems: These systems don’t provide enough power for one of these thermostats. If you have a floor or wall heater, it may be a millivolt unit.
Systems With Stranded Wires: If your system wires are stranded — the insulation surrounds a group of very thin wire strands — contact a licensed electrician to update the system with solid wires.
Wood- or Coal-Powered Systems: Heating systems that use solid fuels are likely not suitable.
Proprietary Systems: If your wiring setup doesn’t look similar to that described in this article, it may be proprietary.
Multistage Heating and Cooling: Depending on the model of your device, it may be able to handle two-stage cooling, but some multi-stage systems aren’t compatible. You’ll need to check your documentation.

Caution

If you have any doubt about system compatibility, contact the thermostat manufacturer or a professional installer. Don’t attempt to install a thermostat on an incompatible system.

Instructions

A silver Google Nest thermostat, a wall plate, a trim plate, two screws and a screwdriver.

Check the thermostat box for the included components. In addition to the thermostat, there will typically be a wall plate or base plate, screws, wall anchors and labels for the system wires. Some models will also include a power accessory (in case your system doesn’t include a C wire to provide consistent power) and a trim kit. The trim kit gives the unit a finished look and covers screw holes from the previous unit.

Read through the manual to familiarize yourself with cautions, warnings and specific installation steps, as well as instructions for connecting the unit to your Wi-Fi network and the dedicated app. We’ll cover the basics here, but always follow your instructions. If you haven’t already, download the app for your smart unit.

Good to Know

The smartphone app associated with your thermostat may also include step-by-step instructions for installation as well as a wiring diagram.

Locate the breaker or breakers for your heating and cooling system and turn off the power to the system. If the thermostat has a display screen, the screen should now be blank. If there is no display screen, adjust the thermostat to several degrees above or below (depending on the season) the current interior temperature. Wait five to 10 minutes to ensure the heat or air conditioning doesn’t turn on.

Once the power is off, remove the current thermostat body from the base or plate that’s fastened to the wall. In many cases, you can simply unsnap the piece from the wall plate. Once you have access to the wires, use a non-contact voltage tester to ensure they aren’t carrying power.

Don’t disconnect the wires at this point. Take a picture of how they’re connected to the wall plate terminals. Make sure any labels or markings on the terminals are visible in the picture. The picture will be a backup in case you run into difficulty labeling the wires.

Caution

As we describe above, if you see only two or four thick wires rather than several thin wires or notice that the wires are stranded, stop. Replace the thermostat body and contact a professional.

Use the included labels from your thermostat kit to mark the system wires according to the markings on the wall plate terminals.

Now, disconnect the wires from the terminals. Secure them temporarily so they won’t fall into the wall.

Good to Know

If you’re in doubt about labeling the wires, check your manual or app. There should be an explanation with details, as well as instructions on jumpers — the short wires you may see running between terminals — and steps to take if your system doesn’t include a C wire to carry consistent power to the thermostat.

Run the wires through the new wall plate and place the plate flush against the wall, ensuring that the plate is level and positioned correctly. Mark the screw hole locations on the wall. Remove the plate.

If you’ll be driving the screws into a stud, you’ll need to predrill the holes.
If you’re installing the screws in drywall, you may need to predrill holes for wall anchors.
Your instructions should indicate the correct bit size for any predrilled holes.

Feed the wires through the center of the trim plate (if equipped) and wall plate and use a screwdriver to fasten the plates to the wall. Don’t overtighten — you could crack the wall and trim plates.

Attach the thermostat body to the wall plate. It may simply snap onto the plate, but there will probably be pins or connections you need to align between the thermostat body and wall plate. Make sure it’s aligned, flush and secure against the plate.

Good to Know

Some thermostats use built-in, rechargeable batteries, but if yours uses disposable batteries, be sure they’re in place before attaching the thermostat.

Setup steps will vary. Your unit’s instructions will provide details and the app should walk you through the process, but you may need to:

Select the display language as well as time and temperature formats.
Specify your heating and cooling equipment type (ex. forced air, radiators, etc.).
For heat pump systems, designate an O wire (the most common) or B wire for the changeover between heating and cooling functions.
Confirm the wiring connections.
Troubleshoot wiring problems.
Test the system and make any adjustments.
Connect the thermostat to a Wi-Fi network.
Create an account in the app and connect the thermostat to it.
Establish basic temperature settings and schedules.
Review your manual or app to learn how to use the menus and options and for information on monitoring energy savings.

Installing a New Thermostat

In most cases, installing a new thermostat is a relatively simple do-it-yourself project that can result in improved comfort and convenience and one that can help you save energy. At Lowe’s, our range of thermostats will make it easy to find a device that offers the controls and features you need. Plus, our associates can help you find one that’s right for your home and your heating and cooling system.

How to Install a Smart Thermostat or Programmable Thermostat

Tools and Materials

Tools

Materials

Thermostat Considerations

How to Replace a Thermostat With a Programmable Model

Instructions

How to Install a Smart Thermostat

Before Beginning Installation

Instructions

Installing a New Thermostat

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