How to Install a Honeywell Home Wi-Fi Thermostat

September 30, 2022September 30, 2022 by Peter In Home Improvement 2 Comments

A rewarding and incredibly useful project for any DIYer!

After installing our new Honeywell thermostat, my wife and I had one of those moments where we looked at each other and wondered how we got by with our old thermostat. The ability to control the thermostat and set our home’s temperature remotely from our phones was a game-changer! We’ve had our new Wi-Fi thermostat for a few weeks now, and in that time we haven’t gone to the physical thermostat once!

I highly recommend this project, and this specific Honeywell thermostat, to anyone looking to upgrade their existing thermostat. These new Wi-Fi thermostats will cost around $150-200 and you’ll need about 2 hours to complete installation. Afterward, when you first set the temperature remotely without having to use the actual thermostat, you’ll be incredibly happy you upgraded your thermostat! So get excited – here’s how to install a Honeywell Home Wi-Fi thermostat.

What You Need to Know Before You Start

Older thermostats are powered by batteries, and because of this they are pretty basic in operation and display a limited amount of information. Modern thermostats – like Honeywell Home Wi-Fi thermostats – have large LED touchscreens that cannot be sufficiently powered by batteries. Instead, these thermostats require a constant source of power through something known as a C wire (also called the common wire). This is just an extra electrical wire that runs from your HVAC system’s furnace control board to an input terminal on your thermostat labeled C, and its sole purpose is to provide electrical power to the thermostat.

Many older, battery-operated thermostats do not require a C wire. So the first thing you need to know before you install a Honeywell Home Wi-Fi thermostat is whether or not your existing thermostat has a C wire. You’ll need to take your existing thermostat off the wall (click here to jump down to Step 2 below that explains how to remove your old thermostat), and check to see if an electrical wire is connected to the C terminal:

If you have a C wire, you can easily install the new thermostat. If you don’t have a C wire, you have two options:

1. Look for an unused electrical wire that you can turn into a C wire

The electrical wires that run from the furnace control board to your thermostat are bound together in a bundle – called a wire bundle. Oftentimes, this wire bundle has more electrical wires in it than your thermostat needs. You can try gently pulling out the electrical wires running to your existing thermostat to see if you can spot the wire bundle in the wall, and if there are any unused wires in (or wrapped around) the wire bundle.

If you don’t see or can’t access the wire bundle from behind the existing thermostat, you can head down to the furnace and open the door(s) to access the furnace control board. When looking at the furnace control board, you can identify the wire bundle from the thermostat based on its electrical wires and their colors, and the fact that the electrical wires that went into the labeled terminals on the thermostat go into the same labeled terminals on the furnace control board. Look for additional wires wrapped around this wire bundle, one of which you can use as a C wire:

2. Use a C Wire Adapter

If you can’t find or don’t have an unused electrical wire to use as a C wire, the next best option is to use a Honeywell Home C-Wire Adapter for Wi-Fi Thermostats:

The C wire adapter gets connected to the furnace control board, taking the traditional four wires from the thermostat as input, and outputs five wires to the furnace control board.

Materials and Tools

This thermostat is awesome, and works perfectly with Total Connect Comfort and the TCC app. Note that this model is listed as a contractor-only model, and thus technically says it needs a professional for installation. It doesn’t, and is virtually identical to their retail model (just a slightly different color/style). If you like the look and feel of their retail model, go with that one:

You’ll want to have a good, standard-sized screwdriver on hand, like this Craftsman Ratcheting Screwdriver Multibit Set:

You’re also going to need a small screwdriver that can access those tiny thermostat terminal connections, such as this Efficere 9-Piece Precision Screwdriver Set:

When securing the new thermostat’s back plate to the wall, you’ll want to use a level to make sure the back plate is level on the wall.

Needle-nose pliers will come in handy when you’re manipulating the thermostat’s electrical wires, and taking them in/out of the thermostat’s terminals.

You may need to trim off the ends of some of the thermostat’s electrical wires, especially if you found an extra wire to use as a C wire.

Oftentimes, new thermostats are smaller than old thermostats. If this is the case for you, after installing the new thermostat you’re likely going to have unpainted parts of the room (or drill holes) that are visible. Instead of repainting the wall that the thermostat is on, you can easily and tastefully cover up any unsightly spots with one of these wall plates.

Step 1: Turn off electrical power to the HVAC system

To protect yourself and your heating/cooling equipment, first turn off power to the HVAC system. This can be done at the main electrical panel. Simply flip the circuit breaker that provides electricity to the HVAC system to “off”:

Step 2: Remove the old thermostat (leave the back plate in the wall for now)

A thermostat is secured to a wall in a two-step process. First, there’s a back plate that is screwed into the wall. (The back plate is also referred to as a wall plate). The electrical wires that send signals from the HVAC system to the thermostat are connected directly into the back plate. Second, the thermostat unit clicks into the back plate via clasps.

It’s helpful to have a visual of the back plate so you can see what these connections look like:

Look around the outside of your thermostat for these clasps, then depress and unclick the clasps to pull the thermostat off of the back plate:

With the thermostat off and the back plate exposed, you’ll be able to see the electrical wires that come from the HVAC system. Before removing the back plate from the wall, be sure to note which electrical wires go into the labeled terminals. For my old thermostat, I had four wires connected to the following terminals: a red wire into the R terminal, a yellow wire into the Y terminal, a green wire into the G terminal, and a white wire into the W terminal:

It’s also a great idea to take a picture of this current wiring before proceeding, just in case you need to reference it later.

Step 3: Disconnect the electrical wires from their terminals, and remove the old back plate

Thermostats vary with how the electrical wires are secured in their terminals. For my old thermostat, I needed a very small screwdriver to unscrew and remove the wires from their terminals:

Then you can use a standard screwdriver to remove the old back plate from the wall:

Tip: if there’s not much slack in the wires and they seem like they might fall back into the wall, you can wrap them around a pencil or screwdriver to keep them in place, like this:

Step 4: If applicable, pull through another wire to use as a C wire

Honeywell Home Wi-Fi thermostats require a C wire. Even though no electrical wire was connected to the C terminal of my old thermostat, additional unused wires were in the wire bundle in the wall. So I was able to pull through an unused wire (black in color, shown with a pink arrow below):

Step 5: Mount and screw the new back plate to the wall

I’d recommend using a stud finder to see if the thermostat is near a wall stud. In my case, the screw on the left-hand side of the thermostat would go directly into a wall stud, whereas the screw on the right-hand side was going into drywall only and needed a drywall anchor:

Insert the electrical wires through the new back plate, and begin to screw the back plate into the wall. Before completely screwing the back plate into the wall, use a level to make sure the back plate is level:

With the level in place and showing a level back plate, finish securing the back plate to the wall.

Step 6: Connect the electrical wires to the new back plate

Ensure the tips of the electrical wires are straight (straighten them with your hand or a pair of pliers if they are bent/crooked), and gently slide each wire into its respective terminal hole until it clicks into place:

If you were able to find another electrical wire to use as a C wire, make sure to connect that wire too! You can also reference the picture you took earlier of your old back plate’s wiring to make sure the wires go into the correctly labeled terminals.

Step 7: Connect the C wire to the furnace control board (alternatively, connect the C Wire Adapter)

Head down to your HVAC system’s furnace (the portion of the system responsible for heating). Open the furnace door(s) until you see the furnace control board – a large circuit board that controls the HVAC system. If you’re unsure of where the furnace control board is or what it looks like, I wrote a post on it here: How to Find the Furnace Control Board in an HVAC System.

This is what the furnace control board originally looked like in my HVAC system. You can identify the wire bundle from the thermostat based on its electrical wires and their colors, and the fact that the electrical wires that went into the labeled terminals on the back plate go into the same labeled terminals on the furnace control board. You can also see additional wires wrapped around this wire bundle, one of which I will use as the new C wire:

Unwrap the extra wires that are around the wire bundle running to the thermostat. Separate out the one wire that you connected to the C terminal in the back plate. Use a wire stripper to expose about a half an inch of wire at the end of this wire (I used the 18 gauge slot to strip the wire):

Using a screwdriver, unscrew (turn counter-clockwise) the C terminal on the furnace control board. Then insert the new C wire under the terminal’s plate, and screw (turn clockwise) the terminal until the new C wire is securely held in place:

Note that if other wires are connected to the C terminal – as I had – leave them in place! Do not remove the other wires! Simply add the new C wire to the C terminal, and make sure the ends of the wires under one terminal don’t touch.

If you didn’t have a C wire to use, you would alternatively connect the C Wire Adapter to the furnace control board per its instructions.

Lastly, put the furnace door(s) back in place.

Step 8: Turn on electrical power to the HVAC system

With work to the furnace control board complete, you can turn on power to the HVAC system. Head back to the main electrical panel, and flip the circuit breaker that provides electricity to the HVAC system to “on”:

Step 9: Attach the new thermostat to the new back plate

Align the new thermostat with the back plate, then push it onto the back plate until it clicks/snaps into place. You’ll see the thermostat power on:

Step 10: Register the thermostat online for remote access

After powering on, the thermostat will guide you through a few screens in order to set initial thermostat options and define your heating/cooling system. After that process you can connect the thermostat to Wi-Fi, but you won’t be able to remotely control the thermostat until you register it online at Total Connect Comfort:

Once you have a Total Connect Comfort account, you can download the TCC app and control your new Honeywell Home Wi-Fi thermostat from your tablet or phone!

Three Useful Thermostat Features to Know About

Honeywell Home Wi-Fi thermostats are packed with a lot of advanced features and settable preferences. Here are three that you’ll definitely want to know about:

1. Inactive Backlight Level

Adding a C wire to the new thermostat means that it has a constant power source and doesn’t rely on batteries. So this thermostat has a pretty cool LED touchscreen that is always on. After using the touchscreen, there’s a short (approximate 10 second) delay until the touchscreen dims slightly and goes into an inactive mode. The default is to set this dimmed backlight to a 5/10 brightness setting. However, there are situations where you might not want the inactive backlight to be on at all (for example, if the thermostat is in a bedroom) – so you might want to set the inactive backlight to a 0/10.

Navigate to this option by going to Menu -> Preferences -> Backlight, adjust the inactive backlight brightness level, and then click Done:

2. Non-programmable vs. Programmable (Scheduled) Thermostat

If you want to use this thermostat like a traditional thermostat – where you always set and control the system mode (cooling or heating) and temperature – then you’ll want to set the thermostat as Non-programmable. On the other hand, if you want the thermostat to automatically raise and lower temperature settings for different times of day (the thermostat follows a schedule), then you’ll want to set the thermostat as Programmable.

Navigate to this option by going to Menu -> Preferences -> Advanced Preferences -> Scheduling Options:

3. Security Settings: Lock Mode and Password

This feature is particularly useful if you have a thermostat in a rentable room/house, or if you have young children who constantly like to press devices and buttons! The lock mode determines which features of the thermostat are accessible without a password:

• Unlocked: full thermostat functionality – no password required to use the thermostat.
• Partially locked: only temperature can be changed without a password. All other thermostat functionality is disabled until the password is entered.
• Fully locked: all thermostat functionality is disabled until the password is entered

Navigate to this option by going to Menu -> Security Settings, then choose Change Lock Mode or Create Password:

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Did this guide help you install your new Honeywell Home Wi-Fi thermostat? Let me know in the comments below!

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