How to Replace a Honeywell Thermostat?


Changing your thermostat is one of those home-care tasks that every homeowner knows is just too easy to put off. You know it’s probably not difficult, but that doesn’t mean you’ll procrastinate on the task any less. The good news? Replacing your thermostat doesn’t have to be complicated or procrastination worthy. We’ve created an easy-to-follow guide to help you cross replacing your thermostat off your to-do list. 

Whatever your reason for replacing your Honeywell thermostat, we’ll show you the safest, smartest way to remove the thermostat, so you don’t get hurt or damage your home. 

Can You Replace Your Honeywell Thermostat Yourself?

That depends on your experience level and whether you need to run new wiring. 

According to CMB AIR, a company that specializes in AC installation and repairs, “When people with no prior experience attempt the DIY installation, there is a risk of damaging the air conditioner or furnace, thermostat, and electrical system. There is also a threat of blowing the circuit breaker and experiencing an electric shock. New thermostats require running new wires, which demands technical expertise for the correct configuration and wiring.”  

There is less of a risk from DIY installation if you are only replacing the thermostat and not installing a new one from scratch (for that, always contact a professional electrician/HVAC system servicer). If you’re an experienced DIYer with electrical or HVAC/cooling system knowledge, you may be able to install your thermostat yourself. 

To know whether you need a professional, consider your thermostat’s wiring and whether it needs to be replaced or rewired. If you’re replacing your Honeywell thermostat with the same model, you likely won’t have to do much rewiring. Instead, you’ll simply attach the new thermostat the same way the previous one was attached. 

Because wiring can be different depending on how old your current thermostat is, it may not be clear how to attach the new thermostat to power. If you’re replacing your Honeywell thermostat with a new, smart thermostat, like Mysa’s Smart Thermostat for AC and Mini-Split Heat Pumps, for example, you’ll want to make sure you’re familiar with the wiring on each device, consult the installation manual, and if in doubt, call a professional to help you make the switch. 

Remember, there are risks when working on DIY projects involving electricity — namely, damage to the circuit breaker or electrical shock — so even if you have experience with electrical work, it could mean the difference between having a new thermostat and having no AC, taking a trip to the ER, and having a damaged breaker box. 

Steps for Uninstalling Your Honeywell Thermostat

Whether it’s a broken thermostat, an upgrade, or a replacement, let’s get that old thermostat off your wall safely with this step-by-step process.

1. Turn off your breaker. This is the first and most important rule for changing a thermostat! The second most important rule? Turn. Off. Your. Breaker.

Check and double-check that there isn’t any power surging through your lines before you go ahead and do any work on them. There won’t be any indication on your thermostat, so have a voltmeter handy to check the line voltage. If you don’t have one, your best bet is to turn up your thermostat and wait 20 minutes. If your heater doesn’t respond and is cold to the touch, you’re ready to move on to the next step.

2. Remove the faceplate and unscrew the thermostat from the gang box. To begin removing your existing thermostat, you’ll need to pull off the faceplate. (You may run into some trouble getting the faceplate off the wall, especially if your old one has been painted over. Just use a knife or something similar to gently pry it off.) If it doesn’t come off with some effort, there may be screws you’ll need to remove first. Once the front is removed, you should see the wiring.

3. Snap a quick photo so you remember which wires go where when you install your replacement thermostat. The thermostat should fall loose now, and you should be able to see the wires.

4. Carefully separate your Honeywell thermostat’s wires that attach the thermostat to the power source. The wiring may be screwed down or may pop out of place with a little effort. Separate the wires from the backplate (also called a baseplate) of the thermostat by pulling them out of whatever is holding them down. TA-DA! Your thermostat should come off with ease.

Now that the thermostat has been removed, you’re going to have to make a decision for a replacement. The two main options for upgrades are programmable and smart thermostats. Now that you can see the wires in your gang box, let’s see if you’re compatible with Mysa. Use our compatibility checker here to find out!

Which Thermostat to Switch To?


The first step up is a programmable thermostat. These have been around for a couple of decades now but are gradually starting to show their age in favor of more advanced, user-friendly technology like connected, smart thermostats. While programmable thermostats will help you maintain a steady schedule, they offer little in the way of advanced control or technology that will further supplement the amount of energy you can save.

Having a set schedule seems nice, but the statistics tell a different story: only 30% of all programmable thermostats are actually set to a schedule at any given time. Why is this? Is it the overly complicated nature of setting them up? Their inaccuracy? Or a combination? Doesn't matter — the point is that programmable thermostats are becoming obsolete in the age of the Internet of Things.


Smart thermostats have become the most sensible, cost-effective, and ahead-of-the-curve way to control the heat in your home. For most forms of home heating systems, a smart thermostat will give you unparalleled control (usually via a touchscreen) and will benefit you greatly compared to simply replacing it with another “dumb” (i.e., non-programmable thermostat) or even a programmable one. Any extra upfront cost will be quickly seen in the savings they provide, the ease of use, and the overall usefulness of all the smart features.

Want a schedule, like the programmable thermostats? Done — and might I add, in much less time. Or you could simply go with geofencing and allow your heat to cut in only when you’re on your way home. Makes everything more flexible, easy, and accommodating for the modern household.

Mysa offers a smart thermostat that requires no installation and integrates with your smartphone. Take a closer look at our digital thermostat’s features here

Steps for Installing Your New Thermostat

  1. Make sure that your breakers are still switched off. Before you begin installing your new thermostat, double-check that the power to the thermostat is still turned off. This step is a safety measure and should never be skipped. 

  2. Look up whether your new thermostat has a c-wire. C-wire stands for “common wire,” and some thermostats need one while others don’t. Your existing Honeywell thermostat is likely connected with a c-wire or c-wire adapter, which means you won’t need to add a c-wire if your new thermostat requires it. If, for some reason, you do need to add a c-wire, it’s best to have an HVAC/air conditioning technician complete this step for the sake of electrical safety. 

  3. Mark the dimensions of the new backplate on the wall. Position the new thermostat’s backplate roughly where the old backplate was. With a pencil, mark the openings for screws so you can easily drill in the right spots. Pull the wires through the opening on the backplate before adhering the backing to the wall. Add screws through their openings and align them with the pencil marks you made before using a screwdriver to secure the plate again. 

  4. Reconnect wires to the correct terminals. Refer back to the photo you took of the wires. Reconnect the wires to the terminals exactly the same way as they are in the picture. 

  5. Add the faceplate and readjust the wires if needed. At this point, you should be able to pop the faceplate (also called a wall plate) onto the rest of the thermostat. If it doesn’t snap into place, double-check that your thermostat wiring is correct or move the wires around so they fit (although you shouldn’t force it to avoid damaging the wires!).

  6. Turn your breakers back on. Your new thermostat should start up automatically after turning the power back on, but if not, consult your installation manual for any further setup instructions. 

  7. If it’s a smart thermostat, connect it to the internet. Once the wi-fi thermostat has been booted up, it should prompt you to finish setup and connect the device to your wi-fi. You may also need to download an app to connect to the thermostat and change settings from a distance. 

Congrats, your smart thermostat is all set up! 

Don’t Forget Upkeep and Maintenance

Whether you DIYed it or called in a professional to replace your Honeywell thermostat, you should now shift your focus to upkeep and maintenance. Ideally, with proper care, your new thermostat will go even further than your previous one in helping you save money and create energy savings. 

If you’re looking for a smart device to replace your Honeywell home thermostat, consider opting for Mysa’s Smart Thermostat. Our smart thermostat allows you to customize your schedule, integrates with your smart home, and requires no installation. Learn more here.

by LastSale
by LastSale