How to Install a Digital Thermostat

Last Updated: March 5, 2020 References

Many older homes have outdated thermostats in which you turn a knob to set it to the desired temperature. These old thermostats can be inefficient and cause heating and cooling bills to rise. Upgrading to a digital thermostat is an inexpensive way to help cut your energy costs while also efficiently regulating the temperature in your home. Some digital thermostats are even programmable, so you will be sure to keep an even temperature in your home throughout the day. Because of all the benefits this simple home improvement can provide, learning how to install a digital thermostat is worth the effort to save money while making your home comfortable and cozy.

Steps

1
Purchase a digital thermostat from a home improvement or hardware store.
2
Turn off the power to your furnace before beginning digital thermostat installation.^{[1]
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3
Remove the cover of the old thermostat.^{[2]
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- Most of them simply pop off easily with a little force.
4
Remove the screws from the screw terminals in the sub-base of the old thermostat and remove it from the wall.^{[3]
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5
Disconnect the wires and label them with masking tape so you know where to connect them to the new digital thermostat.^{[4]
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- There should be letters on the old unit next to each wire. Simply mark each spot with the tape with the corresponding letter on it.
- If the screw holes line up, you can use the old ones. If not, use a drill for new holes and use dry wall mounts if needed.
6
Mount the sub-base of your new digital thermostat over the old location.^{[5]
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7
Attach the wires to the correct terminals in the new digital thermostat sub-base on the wall.^{[6]
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8
Put batteries in your new digital thermostat.
9
Attach the cover of the new digital thermostat to the sub-base on the wall.
10
Turn on the power to your furnace.
11
Set the temperature to your new digital thermostat and experience how efficiently it regulates the temperature in your home.
- If your digital thermostat is the programmable kind, simply program in the desired temperature. It will regulate the temperature in your home to this degree, and keep it there.

Community Q&A

Question

What do I do if there is no blue wire?

Community Answer

If you are talking about the wire for the C (common) terminal you will either need to buy a thermostat that does not require a C terminal or you will have to buy a 24 volt transformer and wire that to an electrical box.
Question

How do I change the battery of a digital thermostat?

Community Answer

You will need to remove the front cover or remove the thermostat from the wall to access the battery.
Question

I replaced the thermostat. The heat is working, but not the air. What do I do if the air does not come on?

Community Answer

Verify you connected the wires in the manner appropriate for your air conditioner. The thermostat should have come with instructions.

Warnings

Follow digital thermostat installation instructions closely to avoid injury or problems.

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Never mix up the wires when installing a digital thermostat. If your old system is a very complicated one and the wires are confusing, you might want to consult a professional for help.

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Never attempt to install a digital thermostat until the power to your furnace is turned off. Doing so could result in shock or electrocution.

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