How to install a Home Thermostat 

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Although installing a thermostat is a simple task, it can have a significant impact on your monthly cooling and heating bills. According to the US Energy Department , thermostat installation can reduce your monthly energy bills by up to 10%. Specifically, a thermostat automatically adjusts your home temperature based on occupancy and the time of the day. As a result, your HVAC system will not cool or heat your home when you’re away, hence increasing your energy savings. However, the installation costs can go up if you hire a professional thermostat installation company to do the job for you. So, if you want to keep that cost down, it’s about time that you learn how to install a thermostat yourself. But where do you get started? Well, continue reading this post to learn more! 

What you’ll need! 

  • Cordless drill 
  • 4-in-1 screwdriver 
  • Level 
  • Drill bit set 
  • Wall anchors 
  • Tape 
  • Clothespin 

How to install a thermostat; step-by-step! 

Before you install a new thermostat, inspect the existing device and wires that run from the heating system. This will help you to determine whether the current set will work with your smart thermostat or if an extra wire is needed. Similarly, if you’re installing a standard manual thermostat, this will help you to familiarize yourself with the device wiring and where it connects to the HVAC system. 

In addition, measure the hole behind the old thermostat to determine if the replacement thermostat will cover the hole. Once you’ve done that, follow these steps to install your new thermostat; 

1. Remove the old thermostat 

Turn off the old thermostat as well as the power to your HVAC system at the circuit box or main fuse. Then remove the cover of the old thermostat. Some of these covers have to be unscrewed, but most covers usually pop off with slight pressure. Whichever the case, after removing the cover, remove the screw attaching the thermostat to the wall. And carefully pull it out of the wall, without removing the wires. 

If you’re dealing with a manual mercury thermostat, handle it with care since mercury is toxic. Mercury in such devices is usually contained in a small glass tube. 

2. Label the wires 

Manual thermostats usually have 2 – 5 wires connected to them. Use a marking tab to label these wires while using the letters on the old screw terminals as reference.

 Alternatively, use masking tape to label the wiring of the existing installation. To accomplish that, attach a small piece of tape to each wire and write the letter indicating where the wire attaches to the old thermostat. In most cases, the letter corresponds to the color of that wire. Once you’ve done that, disconnect the wires and get rid of the old thermostat. 

3. Remove the old wall anchors 

Depending on the size and shape of your new thermostat, it may be necessary to remove the old wall anchors as well as patch the holes. 

4. Install a new faceplate 

Put the new faceplate against the level and mark the locations of the holes you intend to drill for the screws. Make sure you use a level to keep the plate in position, Next, drill 3/16” holes, insert drywall anchors and screw the new faceplate to the wall. If your thermostat comes with backup batteries, make sure you insert them before the wire of the thermostat. 

5. Hook up the wires and install the thermostat 

Using the labels you had marked on the wires earlier, screw the thermostat wiring to the screw terminals of your new device. Luckily, these letters are usually standard, so you can connect them to the same terminals on your new thermostat. 

Lastly, snap the device to the faceplate and turn the circuit breaker or main fuse back on to supply power to the air conditioner and furnace. Now, configure your thermostat to the HVAC according to your schedule to maximize energy savings. The manufacturer’s instructions will come in handy here as they will show you how to program the thermostat correctly. 


Knowing how to install a thermostat is a great way to upgrade your home with an innovative way to control temperature and reduce your electricity bills. Some of these devices, especially the best smart thermostats, are user-friendly since you can easily control them with a smartphone app. All in all, installing a new thermostat is a relatively simple process. Regardless of whether it’s a smart or programmable thermostat. However, before you install any of these thermostats, make sure it’s compatible with your HVAC system! 

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