Installing Wi-Fi thermostat honeywell. Honeywell RTH8580WF Wi-Fi Thermostat review

How To Install Honeywell Thermostat Without C Wire?

Honeywell Thermostat assures comfort inside your home and saves energy costs. You can have Wi-Fi thermostats enabled with room sensors and humidification controls.

These are available in programmable and non-programmable options. However, many of us wonder how we install the thermostat without a C wire.

Don’t worry; we are here to provide you with all the steps to install Honeywell Thermostat without C Wire

Method To Install Honeywell Thermostat Without C Wire

A C wire should be present while installing almost all Honeywell Thermostats. Smart Round Thermostat is the only one that would not require a C wire. The function of this wire is quite simple.

It is a common wire connecting the Wi-Fi thermostat with heating and cooling devices. The C Wire allows a constant flow of 24V AC power to the thermostat.

It’s a wire that connects your furnace to your thermostat. It empowers the thermostat using energy from these devices. Let us look at the steps to follow:

Get The C-Wire Adapter

Yes, a C wire should be there but it will stop the work if you don’t have it. This step is for you. C Wire adapters are readily available in the market that replaces your C wire.

The installation will not be a problem if you have thought of this adapter. This long-lasting equipment is cheap. Not much effort is required, and it indeed solves all your problems.

Good News! A C wire adapter will already be present inside your Honeywell Thermostat. Ensure getting a lifetime guarantee and an adapter that suits the Honeywell thermostat. Give priority to safety and quality.

Check Terminals

Have a look at the terminals. You can access this part after unscrewing the screws in the plate. The designs may differ according to the type you bought. The structure, however, is the same in all the thermostats.

Following are the terminals that we will use:

  • The terminal that gives power to the thermostat – R Terminal
  • The terminal that provides control over the fans – G Terminal
  • The terminal that offers control of the cooling system – Y1 Terminal
  • The terminal that provides power to the heating system – W1 Terminal

The R terminal is for powering the thermostat, which gets done when the circuit completes. Make sure the wiring is correctly done, otherwise, the thermostat will start flashing return.

Make Necessary Connections

As things are aligned, we can begin with connections. Before starting wiring, ensure that the power is turned off for your safety.

The connection of your old thermostat is still intact. Ensure remembering how the wires are put in the terminal.

We suggest you take a picture of where to connect which wire. It will make your new connection go very quickly.

The wires for your heating system go in the W terminal. The cooling system goes into the Y terminal. Use the G terminal for fans to add.

Connect The Adapter

Ensure to connect all the wires to the terminals. You will have to make a slight change because it is without a C wire. The wire in the adapter will go into the R terminal.

After this step, ensure another wire goes into the C terminal. Do not confuse yourself as to which wire goes where. You can go ahead and put any wire in C or R Terminal.

Make sure the connection is intact. No part of the copper particle should be outside of the adapter. We ensure that the power flow goes from the R to W wire and empowers the thermostat through this connection.

Put it Back.

After completing the connection, you can put the thermostat back. Do not put the power on yet. Wait until you put the thermostat back on to prevent a device or short circuit damage.

Keeping the thermostat off before tightly placing it is precautionary. Ensure this because the wiring is low voltage type.

Power ON

Plug it and switch your Honeywell Thermostat on, empowering the whole unit. You will have to wait for the blink on the thermostat. When this happens, the thermostat is good to go.

We recommend a C wire adapter to complete the installation. If your walls are partially complete, run the adapter wires through the wall.

Also, ensure that you follow through with the protocols. Installation should entirely cover the thermostats. This step helps for efficient working.

The Voltage Offerings

Honeywell thermostat comes in line voltage and low voltage systems. The standard voltage for heating and cooling systems is 24 Volts.

We advise you to look at the older thermostat (if available) to decide whether you need a line or low voltage.

The world is getting more innovative, and so are the pieces of equipment. For example, a C wire thermostat ensures more power than a Wi-Fi-based thermostat.

Batteries will drain trying to maintain this level. Some houses use a thermostat with a large and colorful display. One can imagine how much power these devices will need.

How To Install Honeywell Wi-Fi Thermostat Without C Wire?

Honeywell Wi-Fi thermostats have been in use for years now. The installation is effortless and can solve a bigger problem.

Have a look at the steps in this section for a successful installation:

Tools – (for installation)

  • Drill
  • Screwdriver
  • Pencil/ Marker
  • Wire Stripper
  • The Setup box of the thermostat.

Guide To Installation

  • Step 1 – Cut the power and get in your protective clothing and gloves.
  • Step 2 – Remove the thermostat’s outer cover, which gives you access to screws.
  • Step 3 – When you unscrew the screws, you see different wires. Click a picture of these wires to remember which one goes where. You can also refer to the pointers above to see the terminals these thermostats comes with.
  • Step 4 – Take the whole equipment out and hold the wire outside. Use a pencil to keep the wire outside.
  • Step 5 – Now, insert the wires inside the new wire chamber—Mark the spots using a pencil where you will drill the screws.
  • Step 6 – Drill it now and fix the wire chamber correctly. While you are on it, straighten up the wires.
  • Step 7- Put the wire inside the ports and screw them tight at the position. Now is the time for your adapter to come in. If you do not have a wire, connect the wires to the adapter and the adapter to an outlet.
  • Step 8 – Your process is almost done. All you need is to remove the jumper from the R and Rc port and insert the wire. Cover the Honeywell Thermostat and switch the power on to let it function. Ensure to plug the adapter into the outlet.

Enjoy control over fans, cooling, and heating systems. After the setup, get the app downloaded from the play store.

You just would need to make an account by putting down the credentials. Once done, the control is in your hand, using your computer or the app on your mobile phone.

App Name – Total Connect Comfort – Honeywell

Final Talk

We also gave you an option of a NO C WIRE BASED thermostat that is easy to install. You can follow these steps whenever in need or can get expert help if required. Ensure taking precautions on safety parameters.

About Leticia Haupt

Leticia Haupt is a senior staff writer and has tested over 500 home improvement products for BeOnHome.Leticia spends dozens of hours every month poring over crime reports and spotting trends. Her safety expertise is sought after by publications, broadcast journalists, non-profit organizations, podcasts, and more.

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The Honeywell RTH8580WF is a great option for those who want a connected thermostat for less than 100.

Tom’s Guide Verdict

The Honeywell RTH8580WF is a great option for those who want a connected thermostat for less than 100.


  • Inexpensive
  • Works with multiple Smart home systems
  • Robust app
  • Voice control


Why you can trust Tom’s Guide?

Our writers and editors spend hours analyzing and reviewing products, services, and apps to help find what’s best for you. Find out more about how we test, analyze, and rate.

Next-generation Smart thermostats, as described in our Nest Learning Thermostat review and Ecobee SmartThermostat review, are great in that they let you control the temperature of your home using your smartphone, and they can even integrate with other Smart home products. But, at 249 each, they’re not cheap.

Available for less than 100, the Honeywell RTH8580WF Wi-Fi thermostat costs much less, but offers much of the same functionality, which is why it’s one of the best cheap Smart home devices and best Smart thermostats overall for those on a budget.

Editor’s note: This review was originally published in 2016, but has been updated since then.

Honeywell RTH8580WF review: Price and release date

The Honeywell RTH8580WF thermostat was first released in 2012; despite its age, it’s still available for less than 100.

Honeywell RTH8580WF Wi-Fi Thermostat: Design

Unlike the futuristic designs of the Nest and Ecobee, the Honeywell RTH8580WF looks pretty much like every other off-the-shelf thermostat. The white box is roughly squarish (6.4 x 5 inches), with rounded sides, and in the middle is a 3.75 x 2.75-inch LCD touch screen with green backlighting.

The display (whose backlighting turns on when you touch it) was easy to read in the dark, and the touch screen was responsive. While not as sexy as the color displays of the Nest and Ecobee, the Honeywell presents all the pertinent information in a manner that’s easy to read and control.

Honeywell RTH8580WF Wi-Fi Thermostat: Setup

Installing the Honeywell thermostat is no different from other Smart thermostats, but the setup could be more streamlined. After I used the included screws to attach the baseplate to a wall, I connected the appropriate wires to the terminals on the baseplate — you’ll need a small flat-head screwdriver. I then attached the front of the thermostat (the part with the LCD screen) to the baseplate, and the thermostat powered on. To install the Honeywell, you have to have a “C” wire running from your HVAC system. If you don’t, you’ll need to call a technician to install one.

I then downloaded the Honeywell Total Connect Comfort app (a different app from the one used by Honeywell’s Lyric Thermostat) to my iPhone 6s, and created a free account. (It’s also available for Android devices.) Annoyingly, when I selected three security questions, I could only read them when I turned my phone to landscape mode.

Using the Total Connect Comfort app, you then have to connect the thermostat to your Wi-Fi network. You do this by first using your phone to log into the Wi-Fi network that the thermostat created. A screen will pop up, prompting you to enter your home Wi-Fi network’s password. After that, the thermostat should say that it connected successfully. I first tried setting up the thermostat in my office, but there were too many other Wi-Fi signals, and I couldn’t get past this step. At home, though, I didn’t have any issues.

To finish setup, you have to jump through a few more hoops than you would have to with more expensive Smart thermostats. After opening the Honeywell app, you’re brought to a screen titled Locations, under which is a tile that says “Home: No Thermostats Installed.” When you click on this option, you’ll get an error message that says Visit My Total Connect Comfort to add a gateway.”

Next, you’re brought to a web page, where you once again have to log in, and then enter the Mac ID and Device CRC number of the thermostat. After that, the thermostat should appear in the app.

Honeywell RTH8580WF Wi-Fi Thermostat: App

For a budget thermostat, Honeywell’s app is fairly robust. In addition to setting a seven-day schedule, you can also set the thermostat to send you alerts if the temperature changes radically, or if the device disconnects from your Wi-Fi network. However, you can only set up alerts by logging into the thermostat from Honeywell’s Total Connect website, and not from the app itself.

A small microphone in the upper right corner of the app lets you talk to the thermostat to set the temperature, start a schedule and even hear the day’s forecast. In addition, you can say “Hello, thermostat” to Siri (if you’re using an iPhone), and the app will automatically open.

The app also shows the forecast for your area. I doubt I’d go to the thermostat app to check the weather, but it’s nice to have.

You can also link multiple thermostats to the app, which is good if you have a home with multiple zones, or if you want to set up thermostats in several locations, such as your house and a vacation home.

Honeywell RTH8580WF Wi-Fi Thermostat: Smart home integration

Surprisingly, the Honeywell Wi-Fi Thermostat works with a wider range of Smart home systems than Honeywell’s more expensive Lyric thermostat. The RTH8580WF can link to Iris by Lowe’s, Wink, Zonoff, Logitech, Kwikset Kevo, IFTTT, and Lutron, among others. (A full list of connected systems can be found on Honeywell’s site.)

Honeywell RTH8580WF Wi-Fi Thermostat: Bottom Line

The Millennium Falcon of thermostats, the Honeywell RTH8580WF doesn’t look like much on the outside, but it has got it where it counts. It has most of the advantages that come with a connected thermostat — such as being able to change the temperature remotely from your smartphone — but costs less than half as much as premium devices such as the Nest and Ecobee.

You won’t get a slickly designed device, color interface or, as is the case with the Ecobee, a satellite sensor to keep tabs on the temperature in a second room. Still, if you’re on a budget and want to reap the benefits of a Smart home, the Honeywell RTH8580WF Wi-Fi Thermostat could be for you.

Honeywell Wi-Fi (Total Connect Comfort. TCC) Release Notes

The Honeywell Wi-Fi thermostats are a series of Wi-Fi thermostats that have been tested and certified for integration with the ClareHome system.

When integrating a Honeywell Wi-Fi thermostat into your ClareHome project, no extra connections are necessary. Install the thermostat according to the Honeywell documentation, register the thermostat on the Honeywell portal, enable auto mode in the thermostat, and then connect it to the network using IP.

All HVAC drivers share a common UI, so that the user experience is consistent. Temperature settings can be controlled via events. Use Fusion’s Scenes and Rules to automate the actions your customers want.

Supported models:

Econnect Wireless Comfort Control System

Wi-Fi FocusPRO 6000

Wi-Fi 7-Day Programmable

Wi-Fi Smart Thermostat

Prestige IAQ

VisionPRO 8000

Wireless FocusPRO

Note: Models marked with an asterisk require additional gateway equipment for home automation. Refer to manufacturer’s documentation for additional information.

The Following figure shows the Honeywell controls on the ClareHome UI.

(1) Temperature displays on the ClareHome UI in Fahrenheit.(2) Change the Heat set point by sliding the indicator left/right on the bar.(3) Change the Heat set point by sliding the indicator left/right on the bar.(4) Change the Operation mode by tapping the desired radio button. (5) Change the Fan mode by tapping the desired radio button.

Installing the Honeywell thermostat

A qualified HVAC installation technician should install the Honeywell thermostat. Refer to the documentation that came with the thermostat for detailed installation instructions. Clare Controls does not assume any responsibility for damages caused by improper installation or connection to the data network.

Registering the thermostat

After installation, you must register the thermostat on the Honeywell portal. This allows the thermostat to be accessed remotely and updated with information from the Honeywell portal.

To register the Honeywell thermostat:

Note: To register your Honeywell Wi-Fi devices, you must have each device’s MAC ID and Device CRC.

  • Access the Honeywell Wi-Fi portal at
  • Log into the website.– or –Create an account, and then log in.
  • Add a location.Adding the location launches a registration wizard.
  • Complete the wizard to register your devices.Note: You will need the thermostats name for Fusion. The name is case sensitive and must match the name in Honeywell.

Enabling auto mode

Refer to individual thermostat manuals for instructions on activating Auto Mode.

Note: It is necessary to enable auto mode when its used with the Clare Controls App.

To pair the thermostat using ClareHome:

  • Tap the ClareHome app’s Devices
  • Tap Manage Devices.
  • Tap Add Devices.
  • Select the device category, Climate.
  • Select the device type, Honeywell – VisionPRO, FocusPRO, RedLINK Hub.
  • Read through the displayed information, and then tap Authorize Device.
  • Enter your credentials into the Honeywell TCC page and tap Sign In.
  • Read through the provided information and tap Accept.
  • Tap Return to Device List.

To remove the thermostat using ClareHome:

  • Tap the ClareHome app’s Devices
  • Tap Manage Devices.
  • Tap Edit Devices.
  • Tap the 3 dots next to the thermostat, and then tap Remove.
  • Tap Confirm.

Pairing and removing the thermostat in FusionPro

Pair the thermostat to the project.

To add the thermostat in FusionPro:

  • Click Accounts in the side menu.
  • Locate the desired account in the list, and then click View.The Account sub-menu is now available.
  • Click the Devices tab, and then click Add Devices.
  • Select the device category (Climate).
  • Click Honeywell – VisionPro, FocusPro, RedLINK Hub.
  • Click Authorize Device.This will take you to the Honeywell sign in page.
  • Enter the customer’s credentials and click Sign In.
  • Read through the information presented and click I Accept.This will redirect back to FusionPro and show the authorization status.
  • Once the device is successfully authorized, click Return to Device List.

To remove the thermostat with FusionPro:

  • Click Accounts in the side menu.
  • Locate the desired account in the list, and then click View.The Account sub-menu is now available.
  • Click the Devices tab, and then click Delete next to the desired device.
  • Click Delete to confirm.

Honeywell Wi-Fi Smart Color Review

The Honeywell Wi-Fi Smart Color offers users a highly-programmable platform for controlling one’s HVAC system either in person or remotely. Our investigation and testing of this device revealed a thermostat that is easy to install, set up, operate, and program. The device has a large touch-screen that is easy to read, the app allowing remote control is well-designed, and its features are practical. In particular, we liked that we could set temperature parameters to individual days or blocks of days such as weekdays and weekends. Our only complaints about this device are that it is spendy and lacks a backup battery. All told, this is a top-tier thermostat.

Compare to Similar Products

Our Analysis and Test Results

If you are looking for a modern Smart thermostat to help get the temperature in your home or office just right, the Honeywell Wi-Fi Smart Color is the ticket. The unit is a breeze to set up and operate and is also highly programmable.

Performance Comparison

Ease of Use

The ease of use metric is the most important segment of our thermostat assessment because it measures how one interacts with the device and how well the device responds to our effort. This evaluation includes turning on the device and setting it up. The set-up process includes initial time and date programming, scheduling, and advanced settings. Happily, the Honeywell Wi-Fi Smart Color is a class leader in this metric, excelling in the initial set-up and scheduling categories. However, the initial time and date, as well as the advanced settings, were slightly less straightforward.

The Honeywell Wi-Fi Smart Color is easy to use right from the get-go. When you first turn it on, it immediately goes into the set-up procedure. First, you select your language, then you name the installation location (e.g., office), and let it know what portions of the HVAC system it will control (e.g., heating and cooling). Next, you select the heating type (gas/oil or electric), then the cooling/heating stages. Finally, you connect to Wi-Fi and boom, set-up complete.

Scheduling is a bit more involved and a little harder to accomplish than the initial set-up. However, the Honeywell Wi-Fi Smart Color’s scheduling remains one of the easiest to program in the class. Conveniently, there is a ‘Guide Me Through Scheduling’ button that will help you set up schedules — a nice feature to be sure. You can also view any grouping of days or select individual days to program. All in all, the interface is intuitive and easy to navigate.

As we moved on to setting the time and date and the advanced settings, the processes became a little more difficult — but not by much. For example, the initial time and date rely on an internet connection; if you want to change those, you must do it manually. While the advanced settings are fairly simple to program, the sheer number of advanced settings complicates matters slightly. For example, you can create a schedule, set a vacation mode, change the color of the display, check the weather, check equipment status, make temporary changes to the schedule, and access security features. We favor devices that allow customization over ones that limit such actions; however, you should be aware that this will require more time than what is required with a basic device.

Install Support

After the ease of use evaluation, the installation and support metric is the most important portion of our thermostat testing because installing a new electronic device hardwired into a home is, for many consumers, the most daunting aspect of ownership. If you are one of these people, you’ll be happy to know that the Honeywell Wi-Fi Smart Color is among the easiest devices to install, and their customer support is also helpful. We know this to be the case because we assessed the device for customer service, instructions and documentation, Wi-Fi set-up, and app installation.

Our installation and support evaluation is split into four parts that collectively cover all aspects of the device up to the point of programming. Specifically, this includes customer service response time and quality, supplied documentation and instructions, Wi-Fi set-up, and app installation. All told, the Honeywell Wi-Fi Smart Color did quite well in this evaluation, particularly where documentation is concerned. However, Honeywell’s customer service could have been better.

To test customer service, we sent the manufacturer a support email with a photograph of the four wires that feed out of the wall and need to be attached to the thermostat. Our email asks the manufacturer to guide us in attaching these wires to the device. Response time and the quality of the response determine the rating that the device receives. Unfortunately, Honeywell did not respond to us for seven days, at which point we sent a follow-up email that they responded almost immediately. Once we received a response, their email was easy to understand and helpful. The good news is that most people won’t have to send an email to Honeywell because it will be unnecessary. The instructions are easy to understand, straightforward, and accurate.

Finally, the installation and support metric assesses the Wi-Fi set-up and app installation. The Wi-Fi is super easy as it is a required step in the set-up, and the unit’s large digital display streamlines the process. Additionally, the app is a breeze to download, with the sign-in being the highest hurdle.

Remote Access

The Honeywell Wi-Fi Smart Color performed admirably in the remote access metric. This evaluation looks at how well one can control the thermostat with the app on a tablet or phone. We found the Honeywell app to be quite easy to use, and the level of control is relatively high. For example, everything you will want access to is broken up into tabs at the bottom of the app screen with few exceptions. Everything you can access on the device itself is available through the app. You can also see the current indoor and outdoor temperature and humidity, as well as a record of highs and lows.

Scheduling is also a cinch on the Honeywell Wi-Fi Smart Color app. As mentioned, there is a tab at the bottom of the app screen that says scheduling. Once there, you can select the ‘Guide Me Through Scheduling’ button that will help you set up schedules — it’s quite handy. You can also view any grouped days or check each individual day. There are arrows for time, heat, and cool settings for each ‘event’ each day. Finally, making simple, real-time adjustments with the app is a breeze. Just open the app and use the arrows on the main page to increase/decrease the temperature. When you change the temperature, the app enables a ‘hold’ — you can set the time for the hold to end or make it permanent.


When we did our first thermostat review, we didn’t think that temperature accuracy would be a huge factor. However, the temperature inaccuracy of some of the thermostats caught us off guard. The good news is that the Honeywell Wi-Fi Smart Color is among the more precise thermostats in the class.

We tested the thermostats in this review with a laboratory-grade thermometer over a wide range of temperatures. Throughout the range of test temperatures, the Honeywell Wi-Fi Smart Color displayed only minor deviations from the control thermometer’s reading — never were the two devices more than a degree apart.


The Honeywell Wi-Fi Smart Color is not a cheap device. However, it is accurate, easy to use, and sophisticated. If you need a highly programmable thermostat, this is the model for you, and it will be worth the money spent. However, if you don’t need a thermometer with this level of programmability, it will not be worth the outlay.


The Honeywell Wi-Fi Smart Color is one of our favorite thermostats. It is highly customizable, simple to master, has remote accessibility, and looks sharp, too. We have nothing bad to say about this device except that it’s expensive. But, it’s worth every penny if you want a programmable device.

How to Wire Honeywell Wi-Fi Thermostat

The digital world is progressing by leaps and bounds. With each passing day, we have a new gadget on the market.

People seek greater comfort and convenience for their home appliances. For this reason alone, brands introduce innovative products to fulfill consumer demand.

Wi-Fi thermostats are one of the newest inventions that allow you to control your home’s heating and cooling system with your mobile phone.

Honeywell Smart thermostat is yet another popular product in the category. While there’s a buzz around the item, consumers aren’t sure about its wiring process. We’ll uncover it in the guide below.

What Are Wi-Fi Thermostats, And How Do They Work?

Also referred to as Smart thermostats or wireless thermostats, a Wi-Fi thermostat gives homeowners control over their property’s temperature.

Although this is a common phenomenon in almost all heating and cooling systems – families can control the temperature as desired – Wi-Fi thermostats offer a more convenient and advanced method.

It allows you to control your home’s heating and cooling system through your PC or smartphone. Generally, a thermostat is mounted somewhere on your home’s wall, and the device has your IP address, like your PC.

This IP address allows you to connect the thermostat to your home’s Wi-Fi and operate it from your cellphone or computer.

Consequently, you can set a specific room temperature away from your home.

A few advanced models even display outdoor temperature and send you email notifications.

What’s more, most Wi-Fi thermostat models are energy-efficient. So, if you are a frugal homeowner, it will cater to your needs.

Beyond that, some advanced versions learn your daily schedule and adjust the temperature accordingly. For instance, if you’re out working or studying, adjust the temperature remotely. The thermostat examines your particular schedule and changes the temperature correspondingly.

Honeywell Thermostat Wiring Instructions

The trickiest part of mounting a Honeywell thermostat is its wiring. However, the best part is that new Honeywell models use wiring labels similar to the older versions.

Besides, the new versions do not require a C wire. So, if you are swapping a programmable t-stat with the current one, it shouldn’t be a problem. But if it’s the other way round, you’d need a C wire to run your new thermostat.

We got you covered if you recently bought one for your home and aren’t sure how to proceed!

Please stick with us as we reveal the secret sauce of it all.


If your older t-stat contains mercury in its glass tube, discard it properly – mercury is toxic to humans and animals.

Then follow the instructions below.

Collect Your Tools

To begin with, you’d need some tools and equipment to get the job done. We’ve curated a list of some supplies below. However, note that this list isn’t exhaustive, and you might require additional equipment to install your t-stat.

Some standard tools you’ll need include:

  • Wall anchors (to mount the thermostat’s wall plate)
  • Screwdrivers (to tighten or loosen the wire connections)
  • Pliers (to cut the wires, shape them, and strip them)
  • Markers (to mark places on the wall for drilling holes)
  • Drill (for mounting wall anchors)
  • Hammer (To tap pilot holes at the selected locations on the wall where you’ll install the anchors)
  • A level (to determine whether the mounting plate is horizontal or not)
  • Electrical tape (to protect bare wires)

Turn off Your Furnace or Heating System

You need to turn off the power of your central AC unit or furnace. However, make sure you do not do it at your property’s breaker panel.

Generally, furnace installations give an individual power switch to get the job done.

Double-check if the power is off. By examining pilot lamps on an old t-stat or furnace, you can do so.

They should be entirely dark and shouldn’t produce any humming sound.

Get Rid of Old Thermostat

To install a new one, you have to get rid of the old thermostat. You can remove the old one easily from the holder plate.

Most t-stats today come off the wall mounting plate accessibly. This makes the wire hookups even easier. On top of that, it reduces the chance of t-stat damage.

Note that if you have a line voltage system, you may not be able to proceed further. This is because line voltage systems are labeled 120 V or even higher.

It indicates that your system is incompatible, and you need to call in a professional. If otherwise, proceed with the next step.

Check for Wire Labels

The new Honeywell thermostats include a sheet of wire labels. The manufacturers print it with wire letters in most thermostats.

You need to check the wire labels and label them with the terminals.

  • Label red wire with the R terminal
  • White wire with the O/B terminal
  • Green wire with C terminal
  • The yellow wire connects to terminal Y

This will help you when wiring the new plate of your Honeywell thermostat.

Get Rid of the Old Wall Plate

Use a screwdriver to loosen the screws and disconnect the wires. This will help in removing the existing wall plate.

Ensure you do not pull the labels off the wires when removing the plate. Besides, be careful when handling the wires. Often, they fall inside the wall, and it creates nothing but more tension for you.

If you aren’t sure how to prevent them from falling, wrap them around a pen or pencil. This will keep them in place until you mount the new wall plate.

Use a C Wire

The Honeywell thermostat must include a C wire to operate for your furnace or heating system. Otherwise, it won’t work.

If your package doesn’t include a C-wire, you can return it and get a refund.

However, note that you have the option to add a C wire. Here’s how

Prepare an Existing Conductor for Your C Wire

Check for any unused conductors in your current t-stat cable. Installers frequently use a cable with additional wires allowing for easier expansion in the future.

If you get lucky, you’ll find one, and you can use one of those as your C-wire.

You can also find an unused wire in your HVAC system. Open the access door of the unit and find the t-stat set up inside it.

You’ll probably find extra wire inside the system. If you do, remove it from the wire terminals and connect it to the C terminal on the block.

Use a C Wire Adapter

You can also use a C wire adapter to fulfill the need for a C wire. Generally, the Honeywell thermostats include a C wire adapter in the package.

If, however, you use an older version, you may not have one. But you can always purchase a C wire adapter online or in-store.

Check for an Already-Used Conductor

Your existing thermostat may not have additional wires. However, you can use your fan wire for this purpose.

Note that if you take this approach, you won’t be able to use your fan manually.

Check the fan wire in your old thermostat and observe its color. Typically, the wire on the G terminal is green.

Then, return to your heating or cooling system and search for the same wire inside the wiring block of the t-stat.

Remove the G terminal wire, link it to the C terminal, and you’re good to go.

Use a New Conductor

If the thought of losing manual fan operation sounds unpleasant, you have another option. You can run a wire from your furnace to the t-stat.

Although this isn’t a straightforward approach, it works great.

Make sure you choose 20-24 gauge robust wire for the chaser. A more significant number is indicative of the wire’s flexibility and thinness.

However, fragile wires break pretty easily. So, make sure you choose an appropriate number.

Now, run the wire from furnace to t-stat and label both ends as “C.”

Connect the new wire to terminal C and proceed with the Honeywell thermostat installation.

Swap the Thermostat Cable

If nothing else seems to work or the thought of running an entire cable from the cooling system to the thermostat sounds too overwhelming, you can replace the cable.

  • Begin by removing the old cable that might be stapled inside the wall
  • Now, unwrap the new cable to reach the t-stat and place it on the floor to click a photo
  • Remove the conductors of the old wire and disconnect all tapes securing the old cable
  • Attach the ends of the old wire with new ones
  • Pull out the old cable. As you do, it will pull the new wire through the plate.
  • If you cannot pull the old cable for some reason, you need to attach it somewhere else inside the wall.
  • Use fish tape to run the new cable through.
  • This will allow you to pull out the old t-stat cable.
  • Now, return to the furnace and remove the outer cover of the new, unused wire.
  • Strip the wire ends as needed and connect them to the wiring block
  • Make sure you check the wire colors properly and attach them to the wire terminals accordingly
  • Once you see the wires connected, click a picture
  • Go to the t-stat location and strip the new cables to an appropriate length (leave a few inches to be on the safe side)

You are now ready to attach the new cable to your new Honeywell thermostat.

Install New Thermostat Wall Plate

The wall holes must align with the holes of the new plate. Otherwise, you won’t be able to mount the plate.

Luckily, the latest Honeywell thermostat has holes spaced evenly like the old t-stat.

installing, wi-fi, thermostat, honeywell

If the wall holes do not line up with the new plate, you would need to drill some.

We recommend using wall anchors. You can follow the anchor instructions to mount them.

Once the wall holes are in place, install the new plate.

After inserting the plate, tighten it with screws and proceed.

Link the Wires

Here you would need a pair of nose pliers to straighten the conductors.

Cut the bare wire part to a suitable length and insert each end into its corresponding terminal. Simply put, Wire C should go in the C terminal, and Y wire must go in the Y terminal, and so forth.

If you unintentionally push a wire into the wrong terminal hole, you can use a screwdriver to release it. This will allow you to pull out the wire from the other end of the terminal.

installing, wi-fi, thermostat, honeywell

Insert all the cables properly, and no wires should hang outside or closer to the connector plug.

Attach the Wall Plate

Of course, the t-stat shouldn’t hang bare; you have to line it up with the wall plate.

Hold the plate and gently push it to the t-stat unless you hear a clicking sound.

That’s it! You have successfully installed the Smart round thermostat.

Turn On Your Cooling or Heating System

Turn on the breaker you flipped off previously.

If you’ve followed the proper instructions, the t-stat will display the startup screen.

All Honeywell Wi-Fi thermostats display a few options as you power them up. For instance, you’d need to set the temperature, choose a Wi-Fi connection, and adjust other settings per your preferences.


Convenience is a luxury every homeowner adores in a digital world like today. Luckily, Smart Honeywell t-stats take comfort and ease to the next level with greater control.

Install one today and enjoy home automation like never before!

Suhail M

Suhail is a Jack Of All Trades, a Master Of Networks. He is a Network Engineer and specializes in solving complex network issues. is a participant in the Amazon Services LLC Associates Program which means we may get paid commissions on editorially chosen products purchased through our links to retailer sites. All names, logos, brands, and images are trademarks or copyrighted materials of their respective owners. Amazon and the Amazon logo are trademarks of, Inc., or its affiliates.