Are you considering a home upgrade and wondering how to install a smart thermostat? Smart thermostat installation for some systems may be easier than you think. But, it’s important to keep compatibility in mind when shopping for the right smart home thermostat.
The smart thermostat you choose and how it’s installed will largely depend on your old thermostat and the type of HVAC system(s) in your home. For example, installing a low voltage thermostat that controls a furnace is very different from installing a line voltage thermostat for electric baseboard heaters.
To help you out, we’ve put together easy guides for installing smart thermostats for every type of heating and cooling system. From low or high voltage thermostats to AC controllers, we have you covered. But, let’s start with the most important step — finding the right new thermostat for your home.
Finding the Right Thermostat Replacement
When thinking about how to replace an old school thermostat, it’s important to first understand thermostat compatibility. This will tell you ‘what kind of thermostat do I need’ and is an important first step in learning how to install a smart thermostat.
For home heating, thermostats can be broken down into two main categories: low voltage and high/line voltage. If you’re looking to upgrade your AC control, you’ll have to know if you have a ducted or ductless system.
Low Voltage vs High Voltage Thermostats
Low voltage thermostats control central HVAC systems like furnace heating, forced air, ducted heat pumps, and boilers. Generally, if you have low voltage thermostats, you only have 1-2 thermostats in your home. Also, low voltage thermostats are usually labeled to have a capacity of 12-24 volts and have many thin, multi-coloured wires.
High voltage or line voltage thermostats control electric heating systems like baseboard heaters, fan-forced heaters, and electric in-floor heating. Usually, there are multiple thermostats throughout a home, as many as one per room. High voltage thermostats should be labelled as high voltage, with a capacity of 120 or 240 volts. Wires are thicker in size and fewer in number and should be separated into coloured groups (black & red or black & white).
For more info, check out our guide of 4 ways to tell the difference between low voltage vs high voltage thermostats.
Ducted or Ductless AC
AC systems are usually a little easier to distinguish. Ducted air conditioning systems have ducts or vents throughout a home to distribute air. Usually, this is part of a central HVAC system and is controlled by the same 1-2 thermostats that also control the home’s heating. Ductless air conditioning doesn’t require any ductwork. These are zoned systems, so homes usually require multiple units, one in each area being controlled. Examples include ductless mini split heat pumps, window ACs or portable ACs. Ductless air conditioners are usually controlled using a remote.
Other Considerations
When comparing products, it’s also important to consider other compatibility-related criteria like max wattage, connectivity, and the number of wires needed. Usually, you can check this information on a company’s compatibility webpage or an online quiz.
Finally, you might want to compare smart features, smart home integrations, price, customer reviews, and return policy.
How to Install a Smart Thermostat for Each HVAC System
Full instructions about how to install a smart thermostat will depend on your system. So, we’ve put together thermostat installation guides for:
A central heating/cooling system controlled by a low voltage thermostat.
Electric heating controlled by line voltage thermostats.
A ductless air conditioning system controlled by an LCD remote.
1) Low Voltage Smart Thermostat Installation (for Central Heating/Cooling)
First up, is how to install a smart thermostat for a central HVAC system like a furnace or hot water boiler. Some popular low voltage smart thermostat options are Nest and ecobee. If you’re wondering about Nest thermostat installation, this DIY thermostat installation guide is for you.
Step 1: Take proper safety precautions — turn off power to your thermostat & HVAC system. Locate the circuit breaker for your HVAC system and turn it off. If you have a separate breaker for your thermostat, turn that off too.
Check both your HVAC system and thermostat to ensure that no power is flowing to either of them. Try adjusting your thermostat or turning the heat all the way up to see if your heater responds. It’s also a great idea to use a voltage meter to be extra sure that no power is flowing.
Step 2: Remove the faceplate of your old thermostat & take a photo of the wiring. With a little bit of wiggling and effort, your thermostat’s faceplate should pop right off. If it doesn’t then don’t force it; there might be a screw that you need to loosen or a toggle that you need to slide. If you still have trouble, contact a professional HVAC technician for assistance.
Before proceeding any further, make sure you have a way to remember wire placement in each section. Taking a quick photo of your thermostat’s wiring set-up should do the trick. Most wires will be colored or labeled, and your thermostat’s backplate will correspond with these. Some smart thermostats will give you stickers to help with labelling the wires.
Step 3: Disconnect your old thermostat’s wires & backplate. Disconnect each of your thermostat’s wires from the backplate, labelling them as needed. You may have to unscrew wires from the backplate to easily disconnect them. Also make sure not to let the wires slip back into the wall. This can be done by tying fishing line to the wires to secure their position.
To remove your existing backplate, unscrew it and lift it away from the wall.
Step 4: Install the new thermostat’s backplate. Use a level and the holes in your new thermostat’s backplate as a guide to mark screw placement. Securely fix the backplate to the wall using the supplied screws and fixings. It’s best to use a manual screwdriver to avoid possible damage to the backplate, if using a power drill make sure to use the lowest possible setting.
Step 5: Connect the wiring. This is usually the trickiest part of learning how to install a smart thermostat. You’ll need to ensure that the correct wires go into the corresponding sections of the thermostat’s backplate.
Most low voltage thermostat wiring is colored and labeled, so it’s simply a case of matching the wire color/label with the colored/labeled holes on the backplate. However, luckily you have a photo for reference, just in case. To insert each wire, you may have to either push down on a corresponding tab or tighten a screw to secure its placement once it’s inserted.
It’s very important to put the correct wires into the correct ports. If you have older wiring or questions about wire placement, consult a professional HVAC technician.
Step 6: Attach the faceplate. Attach the thermostat’s faceplate to the backplate. This is done by lining up the connectors and turning or sliding the faceplate to secure it in place. It should click securely into place. You may have to switch a toggle or use a provided screw to keep it in place.
Step 7: Turn everything back on. Go back to your circuit breaker and turn on the power to your HVAC system and thermostat. If your faceplate powers on, it means you’ve wired everything correctly.
Step 8: Connect & pair your thermostat. Once everything is powered on, next is learning how to connect your new smart thermostat. This starts by connecting your thermostat to WiFi and then pairing it to your phone. Each smart thermostat app should include a guide to help with this process.
Note that most smart products require a 2.4Ghz WiFi connection. If this is not available, you may have to contact your internet provider for assistance in splitting your network.
Once everything is connected, try adjusting your thermostat from your phone to ensure everything is working properly. Then, you can start to set-up all the energy-saving features!
2) High Voltage Smart Thermostat Installation (for Electric Heating)
Next on our list is how to install a smart thermostat for electric heating. High (or line) voltage thermostats control electric heating systems like baseboard, in-ceiling radiant heat, and in-floor heating.
Remember that these thermostats are high voltage, so proper safety precautions are a must. Please also follow local electrical codes and regulations and have installation performed by a qualified HVAC professional where required.
In terms of a guide, here’s a brief overview of high voltage WiFi thermostat installation. Note: These guidelines are for line voltage thermostats with four or more wires.
Step 1: Take proper safety precautions — turn off power to your thermostat & HVAC system. Locate the circuit breaker for your HVAC system and thermostat, and turn it off.
Make sure to check both your HVAC system and thermostat to ensure that no power is flowing to either of them. Try adjusting your thermostat or turning the heat all the way up to see if your heater responds. It’s also a good idea to use a voltage meter to be extra sure that no power is flowing in the wires.
Step 2: Remove the faceplate of your old thermostat. With a little bit of wiggling and a gentle pull, your thermostat’s faceplate should pop right off. If it doesn’t then don’t force it; there might be a screw that you need to remove or a toggle that you need to slide first. If you still have trouble, contact a professional HVAC technician for assistance.
Step 3: Disconnect your old thermostat’s backplate. Simply unscrew your existing backplate and gently lift it away from the wall.
Step 4: Take a photo of your wiring. Before proceeding any further, take a photo of your old thermostat’s wiring set-up, so you have a reference point. You should see grouped bundles of red, black, and/or white wires attached by wire nuts.
Pro tip: If the wires on your old thermostat are labeled to show L1 and L2, label the group of wires attached to each from the gang box with electrical tape before moving onto the next step.
Step 5: Connect the Wiring. Again, this is the trickiest part in learning how to install a smart thermostat. There can be many variables involved in connecting line voltage thermostat wiring, such as:
The voltage of your existing thermostat
Your type of heating system (baseboard, in-floor, etc.)
How many wires are in your gangbox (in the wall)
The colour of your gangbox wires (black & white or black & red)
How many heaters your thermostat is controlling
At Mysa, we have online installation guides and videos to help you with proper wiring and set-up, as well as a Customer Experience team to answer any questions.
However, if you’re not sure about your wiring set-up, you should not attempt to wire your thermostat and should consult a professional HVAC technician.
Step 6: Attach the Backplate: Once everything is wired correctly, use a level and the holes in your new thermostat’s backplate as a guide to mark screw placement. Securely fix the backplate to the wall using the supplied screws and fixings.
Pro tip: It’s best to use a manual screwdriver to avoid possible damage to the backplate, if using a power drill make sure to use the lowest possible setting.
Step 7: Attach the faceplate. Attach the thermostat’s faceplate by lining it up with the backplate and sliding it into place. You may have to switch a toggle or use a provided screw to fully secure the faceplate.
Step 8: Turn power back on. Go back to your circuit breaker and turn on the power to your HVAC system and thermostat. If your faceplate powers on, it means everything is wired correctly.
Step 9: Connect & pair your thermostat. Once everything is powered on, you’ll need to connect your thermostat to WiFi and pair it to your phone. Each smart thermostat app should include a guide to help with this process.
Note that most smart products require a 2.4Ghz WiFi connection. If this is not available, you may have to contact your internet provider for assistance in splitting your network.
Once everything is connected, try adjusting your thermostat from your phone to ensure that it’s working properly. Then, you can start setting up energy-saving features like Scheduling and Geofencing.
3) Ductless Mini Split or AC Smart Thermostat Installation
Finally, how to install a smart thermostat for ductless mini splits or air conditioners. With a smart AC controller, you can upgrade any ductless mini split or AC unit controlled by an LCD remote. It’s a quick and easy upgrade that can be done in minutes.
Step 1: Plug in your smart thermostat for mini splits/AC. Plug your new smart device into an outlet close to your mini split or AC unit. It’s important that your smart AC controller has a direct line of sight to your mini split heat pump or AC conditioner.
Step 2: Connect to WiFi. Connect your smart AC controller to WiFi using instructions in the smart thermostat’s app.
Note that most smart products require a 2.4Ghz WiFi connection. If this is not available, you may have to contact your internet provider for assistance in splitting your network.
Step 3: Pair your smart thermostat. ‘Pairing' means connecting your thermostat to your mini split or air conditioner using WiFi. This is how you can control your mini split or AC unit from your phone and access all the app features.
To pair, start by choosing the type of AC unit you have (ex. mini split, window AC, etc.), and enter your AC or mini split unit's brand.
Next, turn your current remote on and off while pointing it towards your smart AC thermostat. This helps match the infrared (IR) commands from your remote to the smart thermostat's database. After finding a match, the smart thermostat downloads all of the commands for your existing remote to give you full control.
Step 4: Set-up smart features. Once you finish pairing, you’re free to set schedules, turn on Geofencing, and take advantage of all other app features. It’s a major upgrade to your old AC thermostat control!
How to Install a Smart Thermostat — FAQs
Further to our smart thermostat installation guides above, we’ve put together answers to some commonly asked questions about how to install a new thermostat.
How to Change a Thermostat?
Once you have the right thermostat replacement, you’re going to have to remove your old one. Learning how to replace a thermostat will vary depending on your HVAC system and old thermostat. So, we suggest following one of the more detailed guides above for each HVAC system.
However, here’s a general guide that describes how to change thermostats:
First, take the proper safety precautions by turning off your HVAC system and thermostat at your energy breaker panel. Before proceeding to the next step, ensure that the breaker is off and consult a professional HVAC technician if you’re unsure.
Remove your old thermostat’s faceplate.
Take a photo of the wiring so you can use this as a reference point for re-wiring.
Remove and disconnect wiring from your old thermostat and the backplate by unscrewing it from the wall.
Connect the wires from your HVAC system to your new thermostat and install the backplate.
Put on the new faceplate.
Turn your HVAC system back on at the breaker panel.
Connect your new smart thermostat to WiFi and begin pairing.
This information is intended as a rough guide. These are not exhaustive instructions, and there may be additional steps involved (e.g., installing a C-wire) depending on your HVAC system.
You should always take proper safety precautions and abide by your local laws and regulations for installing thermostats where applicable. Always consult a professional if you’re not sure and where this is required by law.
How to Remove Your Thermostat Cover?
Regardless of what thermostat you currently have, you’ll need to remove its faceplate to obtain access to the wiring and backplate. Generally, it’s a pretty simple step in learning how to install a smart thermostat.
With a little bit of wiggling and effort, your thermostat’s faceplate should pop right off. If it doesn’t, then don’t force it; there might be a screw that you need to remove or a toggle that you need to slide first.
If you have any trouble with removing your faceplate, consult a professional. Please do not try to forcibly remove your faceplate or try to break it as this is dangerous and could lead to damaged wiring.
How to Remove Your Thermostat From the Wall?
Once the faceplate is removed, it’s a good idea to take a photo of your thermostat’s current wiring set-up before disconnecting anything. This gives you a good reference point when installing a new thermostat, in case you have to seek assistance. This step in learning how to install a smart thermostat can get a little tricky.
It’s very important that you’ve taken proper safety precautions before this stage to make sure your thermostat and HVAC system are turned off at the breaker. You can double check this by using a voltmeter to make sure there are no live wires. Or by turning up your thermostat all the way to see if your heater responds. This helps prevent short circuits and ensure your safety.
Then it’s time to remove your thermostat from the wall. How this is done will depend on if you have a low voltage or high voltage thermostat.
For a low voltage set-up, you’ll have to unscrew each wire and pull them out of their slots in the backplate before unscrewing the backplate and removing it. Pro tip: Do not let any wires fall back inside the wall. To prevent this, you can tie fishing line to the wires to maintain their position.
For a high voltage set-up, you’ll likely have to remove the backplate before you can get to the wires. Simply unscrew the thermostat backplate and gently pull the backplate from the wall, revealing its wiring and the gangbox. Again, before disconnecting any wires, make sure to take a photo as a reference point.
Do I Need a Common Wire (‘C-wire’) for a Low-voltage Smart Thermostat?
Most conventional (i.e., non-smart) thermostats don’t need a c-wire to function. Smart thermostats on the other hand do. This is because smart thermostats need a constant supply of power, which is delivered through a c-wire.
Chances are that your old thermostat doesn’t have a c-wire. However, you can check this by removing your current thermostat’s faceplate and looking for a terminal labeled with the letter “c”. If there’s a wire attached to this terminal, you have a c-wire.
If you don’t have a c-wire, there are a few options. You could use an extra, unused wire as a c-wire (provided that you have got an extra wire available) or install a c-wire add-on kit or adapter. These can be purchased from various manufacturers and are relatively straightforward to install. If in doubt, however, always consult a qualified electrician.
How to Install a Nest Thermostat?
Ecobee and Nest thermostat compatibility is for central HVAC systems. So, if you’re curious about ecobee installation or Nest installation, follow the DIY smart thermostat installation guidelines above for low voltage smart thermostats (the first guide on our list).
Is My Thermostat compatible with Nest or ecobee?
Ecobee and Nest thermostat wiring is low voltage, so either make a great upgrade when replacing an old thermostat controlling a central HVAC system. If you have a low voltage thermostat that controls central heating and/or cooling, then your thermostat should be compatible with Nest or ecobee.
How Many Wires Do You Need for a Smart Thermostat?
Smart thermostat wiring requirements depend on your old thermostat. To understand what you should look for in terms of smart thermostat wiring, it’s important to understand thermostat compatibility. This comes down to understanding the difference between low voltage vs high voltage thermostats.
Prepare for Smart Savings
A smart upgrade for your old-style thermostat is an easy way to increase your home’s efficiency and help you save on your monthly electric bill. Plus, smart heating and cooling control comes with plenty of added convenience.
Learning how to install a smart thermostat can be a simple project, just make sure to keep thermostat compatibility in mind. It’s important to first find a smart thermostat that’s compatible with your HVAC system, so you can follow the right installation instructions.
To learn more about smart thermostats and how they help you save on your electric bill, subscribe to Mysa’s email list.