How to replace a thermostat

Working around electricity can make anyone a little anxious, and some homeowners might get nervous if they need to replace a thermostat. Fortunately, replacing your thermostat is a fairly easy task to accomplish, and the savings and efficiency of your HVAC are well worth the effort.

Step 1 – Prep

Make sure the new thermostat is compatible to your 110-volt housing circuitry before you purchase it.

Step 2 – Switch Off the Power

Always turn off the electricity to the home thermostat at the power panel or circuit breaker box. Once you’ve located the correct circuit breaker and have switched it off, place a piece of masking tape over the switch so no one will turn it back on during your replacement installation process.

Step 3 – Remove Old Unit

Remove the old unit by snapping the cover off or unscrewing it if is attached by a set of screws. Pull the unit away from the wall and slide it off the mounting plate. Be careful not to damage the wires.

Step 4 – Disconnect Wiring

Remove the electric power supply wiring from the back of the thermostat. To prevent the wires from falling back into the wall, wrap them around a pencil so they can’t fit through the entry/exit hole. If the wires are not color-coded to the new thermostat, mark each one, noting the terminal they were attached to. Then, remove the mounting plate.

Step 5 – Attach New Mounting Plate

Place the mounting plate for the new thermostat against the wall in the same spot as the old one. Now, pull the wires from the wall through holes in the back of the new plate, and screw the plate into the wall. Make sure it is square to the wall and adjust the unit for leveling before tightening the mounting screws.

Step 6 – Connect Wires

When connecting the wires, make sure the green wire is connected to the terminal marked “G” or the same color. This operates the furnace fan blower. The white wire goes to the “W” marked terminal to operate the heater while the “Y” is for the yellow wire that connects to the air conditioner. If the wires were not color-coded, make sure to follow the labeling you created, and do not cross wires. If in doubt, call a professional electrician.

Step 7 – Mount on Mounting Plate

Place the unit on the mounting plate by sliding it into place. Turn your power back on and check to see if your new thermostat is working properly. Follow the manufacturer’s instructions for setting up the LED display panel that gives you access to temperature control and you’ll be set to go.

How to replace a thermostat

I’ve been slowly turning my home into a “smart home.” I want to be able to control my heating/cooling/lighting/electrical systems from anywhere in the world with my tablet or smartphone, just like some space-aged-homeowner-as-imagined-by-1950s-futurists would.

Today I’m replacing my old thermostat with a Honeywell Lyric thermostat that connects to the web. With the new device, I can change the temp in my house from my phone and I’ll get updates when I need to replace the filter. My dream of becoming George Jetson will be one step closer!

I’ll admit, replacing a thermostat — with all the wires and the breakers and the electric doo-hickeys — kind of intimidated a DIY-noob like myself. I didn’t want to make some wrong connection on the new thermostat and blow up my furnace. But after a bit of research, I discovered that replacing a thermostat is pretty stinking easy.

In case any of you ever find yourself needing to replace an old thermostat, I’ve documented the steps below, with photos, on how I replaced my old one with a Honeywell Lyric. Granted, each heating and air conditioning system will have unique requirements for connecting a new thermostat, but the general process is pretty much the same. Consider this your big picture guide through the process.

1. Turn Off Power to A/C and Furnace

How to replace a thermostat

Better to be safe than sorry. Turn off the power on the air conditioning and furnace units associated with your thermostat. You can do this by going to your breaker box and flipping off the respective switches. Another way you can turn off the power on your A/C and furnace is to simply flip off the power switch on the units themselves.

To confirm that the power to your unit is off, adjust the temperature on your current thermostat to either really hot or really cold and see if the A/C or furnace turns on. If they don’t, you’re golden.

2. Remove Face of Old Thermostat

How to replace a thermostat

3. Take a Picture of the Wires

How to replace a thermostat

This step isn’t strictly necessary (you’ll see why below) but it’s nice to have a reference for which color wire should go into which receptacle on your new thermostat.

4. Disconnect Wires from Old Thermostat

How to replace a thermostat

Depending on your current thermostat, you may need a small screwdriver so you can untighten the screws that are holding the wires in place. I had to use a screwdriver that you use for eyeglasses.

5. Remove Old Mount

How to replace a thermostat

6. Put on the New Thermostat Mount and Connect Wires

How to replace a thermostat

Connecting the wires on your new thermostat isn’t that difficult. On the mount, you’ll notice that there are letters. Each letter stands for a different colored wire: “G” – green, “R” – red, and so on. Simply insert each colored wire in its corresponding initialed receptor. The receptors on the Honeywell Lyric don’t require screws to keep the wires in; I just pushed them in until they locked in place.

7. Screw Faceplate Mount to Wall

How to replace a thermostat

You may need to install some drywall anchors so that you can securely screw on your faceplate mount. Lucky for me there were already two drywall anchors in place behind the old thermostat in exactly the right spot for my new one.

8. Attach New Thermostat Face

How to replace a thermostat

If you’re having problems with this step, adjust the cognitive thermostat in your brain.

9. Turn Power Back On to A/C and Furnace

How to replace a thermostat

Turn your power back on to the A/C and furnace. As you can see, I’m using the same image that I used for turning the power off, because it’s basically the same step, and I’m lazy.

10. Configure New Thermostat

How to replace a thermostat

Every thermostat is going to be different when it comes to configuration, so just follow the steps in the user manual that comes with it. The Honeywell Lyric thermostat connects to your wireless network so that you can configure and control it from your smartphone or tablet from anywhere in the world.

The free Lyric app took me through the set-up and configuration process. Besides the usual “Away” and “Home” schedules that you can create on most thermostats, the Lyric lets you create a “Geofence” within the system so that when you leave the house with your smartphone, the thermostat will automatically set itself to a more energy efficient temperature. It also has a “Fine Tune” feature that considers both indoor and outdoor humidity and temperature to adjust your settings so that your desired temperature always feels the same. I did a few tests on both of those features to make sure they work and all systems were go.

Well, there you go. You now know how to install a new thermostat. Don’t be intimidated by the wires. It’s such an easy job that even a guy who never took shop in high school and blogs for a living can do it.

Skill Level

Start to Finish

Tools

  • screwdriver
  • putty knife
  • wire cutters
  • paintbrush
  • level
  • drill with 1/8″ bit
  • needle-nose pliers

Materials

  • new thermometer
  • sandpaper
  • lightweight wall spackling compound
  • paint

How to replace a thermostat

How to replace a thermostat.

How to replace and install a new smart thermostat in your home.

Photo by: Emily Fazio ©2015

Emily Fazio, 2015

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Step 1

How to replace a thermostat

How to replace a thermostat

How to replace a thermostat

Remove Old Thermostat

Remove the cover of your existing thermostat and loosen the screws that secure the base of the product to the wall. Thermostat wires are low voltage, but it’s always advisable to turn off power running to the unit before disconnecting the wires.

Step 2

How to replace a thermostat

How to replace a thermostat

Label Wires

Make a note or use masking tape to label which wire is which before you disconnect to make reattaching the wires easier.

Once the wires are disconnected, if necessary, use needle-nose pliers and wire cutters to prepare the wire for being attached to the new product.

Step 3

How to replace a thermostat

How to replace a thermostat

Assess Needed Wall Repair

If the footprint of the new thermostat is different from that of your old thermostat, there are a few options to consider. Your new thermostat may come with a wall plate that sits between the base of the product and the drywall. Wall plates will cover a wider surface, sometimes completely eliminating the need to do extra wall refinishing.

Step 4

How to replace a thermostat

How to replace a thermostat

Repair Drywall

If you choose to avoid using the wall plate, there may be holes that need to be patched and sanded and paint that needs to be touched up. Use lightweight wall spackling compound and a putty knife to repair holes and sandpaper to create a smooth surface. Use a paintbrush to perform touch-ups. Allow the paint to dry completely before installing the new product.

Step 5

How to replace a thermostat

How to replace a thermostat

How to replace a thermostat

Emily Fazio, 2015

How to replace a thermostat.

How to replace and install a new smart thermostat in your home.

Photo By: Emily Fazio ©2015

Attach New Thermostat

Follow instructions to attach the base of your new thermostat to the wall. Using a level (it may be built in to the thermostat itself!) mark the holes for new screws and then pre-drill into the wall using the drill and a 1/8” bit (or recommended size). Use the screwdriver to attach the base of the thermostat to the wall.

Step 6

How to replace a thermostat

How to replace a thermostat

How to replace a thermostat

Emily Fazio, 2015

How to replace and install a new smart thermostat in your home.

How to replace a thermostat.

How to replace and install a new smart thermostat in your home.

Photo By: Emily Fazio ©2015

Connect Wires to New Thermostat

Thermostat wires for a typical heating unit will be required to connect to the W and R spaces on your product. With the NEST product shown here, the straight copper wires are inserted into two plugs, rather than wrapping around screws.

Once again, follow directions provided with your product if your HVAC system is more complex.

The front of the new thermostat will simply plug into the base. If you’re using a smart home product, follow directions on the screen to set up the product, and then test it to be sure that it correctly activates your HVAC.

How to replace a thermostat

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Replace your old thermostat to remove unsightly, discolored plastic housing or metal-domed thermostats with sleeker, more economical digital-display thermostats. Thermostats manufactured before 2005 with a sliding tab or turn knob often come with a glass vial of mercury that is used to run the furnace. These thermostats can be safely recycled at HVAC wholesale distributors, of which there are over 350 collection locations in California, to ensure that mercury is reused.

Turn off the power to the thermostat at the circuit-breaker box of your home.

Take the housing off of the old thermostat. Remove the screws that are holding the thermostat to the wall and gently pull the thermostat away from the wall to expose the wires.

Examine where the wires are connected to the thermostat’s terminal screws. There is a wire for the heater and there may be a wire for the air conditioner as well. The terminal screws for each device that the thermostat is connected to should be marked with letters such as W, Y, G, RC and R. Before you remove the wires, wrap a piece of masking tape around each wire to form a tag with the tape. Mark the masking tape with the letter designation of each wire’s terminal screw with a felt-tipped pen.

Loosen the terminal screws with a screwdriver and gently unhook the wires from the screws. If the wires want to pull back into the wall, tape them down with masking tape to hold them in place. Put the old thermostat in a safe place so that you can recycle it properly as most old thermostats contain glass tubes with mercury.

Remove the thermostat’s mounting-plate screws and take it off the wall. Hold the new thermostat’s mounting plate up to the wall to check whether you need to drill new holes for the mounting-plate screws. If you do, as newer models are a different size and shape than older thermostats, hold the mounting plate straight, check its position with a carpenters level and adjust accordingly to make it straight and even. Mark the places for screw holes on the wall with a pencil.

Drill holes into the wall at the pencil marks. Drive drywall anchors into the wall with a hammer until the ends are flush with the wall. Place the mounting plate onto the wall, thread the wires through it and then set the provided screws into the drywall anchors and tighten them with a screwdriver.

Inspect the ends of the thermostat wires. If they are frayed or corroded, use wire cutters to cut off the ends. Strip 3/4 inch of the insulation jacket off the wires with wire strippers to expose the metal underneath.

Loosen the new thermostat’s screw terminals. Wrap the wire with the corresponding letter clockwise around each screw terminal. Tighten the screws. If you find that the screw terminal designations are different on the new thermostat, the instructions that came with the new thermostat’s packaging should have a chart or instructions to guide you with the wiring process.

If you have wires marked C or C1 that connected to terminal screws on the old thermostat, do not connect them to the new thermostat. Separate the C and C1 wires from the other wires. Wrap the end of the C and C1 wires with electrical tape to completely cover the bare metal end. Gently insert the wires into the wall.

If there are any other wires in the wall near the old thermostat that were not connected to the old thermostat, wrap the ends with electrical tape and gently place them into the wall.

Push the wires into the wall. Insert the provided batteries into the thermostat as needed. Attach the thermostat to the wall plate by sliding the tabs of the wall plate into the back slots of the thermostat and snapping it into place. Turn the power back on at the circuit-breaker box.

Welcome to the Take Charge of Your Home series from Direct Energy! Hiring a professional to perform household maintenance may offer convenience and peace of mind. You can do many of these jobs yourself with no experience or special tools. In the process, you’ll save money, learn about how your home works and gain a sense of accomplishment. A DIY task done well!

Central heating and air conditioning are two of the most essential systems in many homes, and neither of them can function without a thermostat. Homeowners with the “if it ain’t broke, don’t fix it” outlook may have perfectly serviceable thermostats that are decades old. But in this age of smartphones and wifi, there’s a lot to be gained in upgrading your thermostat — and who knows, your old faithful thermostat could finally bite the dust.

Diagnosing a Broken Thermostat

The most obvious reason to replace a thermostat is because it’s broken. Thermostat failure can sometimes be tricky to diagnose on your own, because you could also suspect problems with your heating and air conditioning systems. If you don’t have DIY experience with thermostats and HVAC systems, you may need the assistance of a licensed HVAC technician to affirmatively pinpoint the thermostat as the source of your problems.

Some of the most common symptoms of a broken thermostat include:

  • The actual indoor temperature as measured by a separate thermometer is different from the temperature displayed on the thermostat
  • The HVAC system doesn’t turn off when the temperature reaches the thermostat setting
  • The HVAC system doesn’t turn on when the temperature changes from the thermostat setting
  • The thermostat is unresponsive
  • A battery -operated thermostat drains fresh batteries too quickly

Should You Replace Your Manual Thermostat?

Just because your old thermostat works doesn’t mean it isn’t costing you an opportunity to save money. Manual thermostats — whether they’re digital or the old-fashioned analog dial — can only be changed by a person interacting with them directly. But with a programmable thermostat — or better yet, a smart thermostat — you can exert greater control over your thermostat so that you’re not wasting energy maintaining temperatures that no one is home to enjoy.

Advantages of a Programmable Thermostat

Digital programmable thermostats are comparable in price to manual thermostats and offer money-saving features, so there’s no reason not to choose this type as the minimum standard for thermostat replacement. Some features may vary from one programmable thermostat to another, but the primary feature is that these thermostats let you set different temperatures for different days and times. While everyone is at work and school, the thermostat can be set a few degrees lower in the winter and higher in the summer. Over time, the energy savings can more than pay for the cost of the upgrade, all while helping the environment the entire time.

Advantages of a Smart Thermostat

The state-of-the-art option, though, is the smart thermostat. Smart thermostats can be controlled from anywhere in the world via smartphone or tablet apps. These apps make setting schedules easy and elegant, but whenever your plans change, you can take control with a few taps of your phone. There’s an even greater variety of features among smart thermostat brands, such as intuitive technology that “learns” your schedule and settings that respond to outdoor weather conditions.

Which New Thermostat Is Right for You?

Given the unparalleled features of smart thermostats, there are a lot of reasons to go big with your next thermostat upgrade. But smart thermostats aren’t necessarily the perfect fit for everyone. For instance, smart thermostats can’t function without access to wireless Internet, and they’re not practical for homeowners who don’t use smartphones or tablets. So if you don’t have both wireless internet and a smartphone or tablet, you’ll get much more benefit from a programmable thermostat.

Smart thermostats are more expensive than programmable thermostats, and if you pay an HVAC technician to have yours professionally installed, the installation costs could also be higher. It all depends on the existing wiring within your walls.

Another consideration is that smart thermostats aren’t compatible with all heating and cooling systems. If you have central air conditioning and heating or a heat pump, it’s likely that you’ll be able to integrate most smart thermostat models into your home. But if you have radiator heat, baseboard heaters, swamp coolers or other less common components in your HVAC system, there may be compatibility issues. You should check the product specifications of each smart thermostat you’re considering to make sure they’re compatible with the equipment in your home.

All that said, if you’re a smartphone user with wireless internet, a compatible HVAC system and enough money to purchase and install a smart thermostat, the savings potential of this technology is enough to pay for the cost of the upgrade over time.

Ready to replace a thermostat in your home? Choosing the right thermostat isn’t the only big decision — you’ll also need to decide whether to install it yourself or hire a pro, which is what we’ll explore when we return with part two of this project.

About Josh Crank

Josh Crank is a freelance writer and content marketer with a background in legal journalism, travel writing, and marketing for numerous commercial industries. He’s found his perfect fit at Direct Energy in writing about home maintenance and repairs, energy efficiency, and smart home technology. Josh lives with his wife, toddler son and endlessly howling beagle-basset hound mix in New Orleans.

In the market for a new thermostat?

To help you navigate the wide world of thermostats, we’ve created a step-by-step guide to help you choose the right replacement thermostat for your home.

Choosing a replacement thermostat involves 3 easy steps:

  • Choosing the type of thermostat you want
  • Making sure it can work with your home and HVAC equipment
  • Contacting a pro to help you install it

Want to talk to a pro to walk you through the process? Give us a call—we’re happy to help.

Contact us today

Step #1: Choose the type of thermostat you want

We often get this question from Arizona homeowners: “What kind of thermostat do I need?”

In this section, we’ll go into the 3 main types of thermostats, and discuss their pros and cons.

1. Manual thermostats (good)

Also called “mechanical” or “non-programmable” thermostats, manual thermostats are the most basic type of thermostat you can buy. You must manually adjust it to turn your HVAC system on and off and control the temperature.

You can buy 2 types of manual thermostats:

The downside to manual thermostats is that some models aren’t the most precise when it comes to temperature control. In fact, some manual thermostats have about a +/- 3° differential, while other types of thermostats only have a +/- 1° differential.

2. Programmable thermostats (better)

Programmable thermostats do just what their name suggests: they can be programmed to save you money on your energy bills. In fact, according to Energy.gov, programmable thermostats can save you up to $180 per year in lower energy bills.

For example, if you’re at work 5 days a week for 8 hours, that’s 40 hours every week during which you can dial back your AC or heating system to save you money. And sure, you can turn your HVAC system off with a manual thermostat, but that means you’ll always come home to uncomfortable temperatures.

A programmable thermostat solves this issue by telling your HVAC system when to turn on/off and to what temperature, so you don’t have to do it manually.

Here’s how it works:

If you leave the house at 8 am and don’t come back until 6 pm, you can program your thermostat to automatically raise or lower (depending on the season) your home’s temperature by 10° right at 8 am. Then, you can set it to automatically return to comfortable temperatures at 5:30 pm so that the house is comfortable by the time you get home.

3. Smart thermostats (best)

Smart thermostats are programmable thermostats taken to the next level of connectivity and comfort. You can control these thermostats from your computer, tablet or phone which means you can adjust your home’s temperature remotely.

Though they are the most expensive, these thermostats have the best comfort features and also save you money every month on your utility bills.

Some comfort features you can find on smart (and some programmable thermostats) include:

  • Touch screen displays
  • Voice instructions and notifications
  • Dirty air filter alerts
  • Multiple programmable schedules (weekday, weekend, vacation, etc.)
  • Schedule “learning” capabilities (where the thermostat learns your daily schedule automatically instead of you having to program it)

Step #2: Make sure it can work with your home and HVAC system

Once you determine the kind of thermostat you need, you’ll want to be sure that you pick a specific model that’s compatible with your HVAC system.

To make sure a thermostat is compatible with your system, check that it can work with:

  1. Your system’s specific voltage
  2. The location on the wall
  3. The # of heating/cooling stages your system has

Let’s go into more detail about each of these points.

#1: Check your system’s voltage

Your HVAC system either is a low voltage, millivolt or high voltage system. You’ll need to get a thermostat that is compatible with your system’s voltage requirements.

Most thermostats work with low voltage systems. And the good news is, unless you have wall/floor heaters or an electric baseboard heating system, you most likely have a low voltage system because they are the most common.

How to confirm your thermostat works with a low voltage system:

Look at the specs on the thermostat box or manufacturer label. If you’re looking online, look for the words “low voltage,” as seen in the screenshot below:

Screenshot taken from Google Shopping on 01/25/2018.

Note: If you have wall/floor heaters or an electric baseboard heating system, you either have a millivolt or high voltage system, respectively. You’ll want to contact a professional for help choosing a thermostat that works with those systems.

#2: Make sure the thermostat fits on your wall

Don’t forget to verify that the new thermostat will fit in the same location so you don’t have to mess with rewiring. Also, keep in mind that if your home is zoned, each zone has its own thermostat so you’ll need to purchase multiple thermostats.

Not comfortable doing these steps yourself? Contact a professional to make sure your new thermostat is compatible with your system.

#3: Have a pro determine the # of heating/cooling stages your system has

“Stages” refers to how many speeds your AC or heating system can run.

Your HVAC system will fall into 1 of the following categories:

  • 1-stage = the system works at full speed, or off (like an ON/OFF switch)
  • 2-stage = the system works at a LOW or HIGH speed
  • Variable speed = the system can ramp up or down its cooling/heating levels depending on what’s needed at any moment

The bottom line is that you’ll need to confirm that your thermostat’s wiring is compatible with the number of stages your HVAC system has.

Since this step requires you to “read” your current thermostat wiring, it’s best to have a professional handle this for you.

Step #3: Contact an HVAC expert to help you install it

The easiest (and safest) way to install your thermostat is to have a professional do it for you.

An improperly installed thermostat (due to a DIY attempt) can result in:

  • HVAC system malfunctions
  • Lowered comfort (improper wiring can even leave you without cold/warm air)
  • Expensive repairs
  • Unnecessarily high monthly energy bills

Hiring a pro guarantees that your thermostat will work with your system and that you won’t run into any problems down the road.

Need thermostat advice or an install?

Just give us a call. We’d be happy to answer any questions you have or help you schedule an appointment with one of our trusted techs to install a new thermostat for your home.

Welcome to the Take Charge of Your Home series from Direct Energy! Hiring a professional to perform household maintenance may offer convenience and peace of mind. You can do many of these jobs yourself with no experience or special tools. In the process, you’ll save money, learn about how your home works and gain a sense of accomplishment. A DIY task done well!

Central heating and air conditioning are two of the most essential systems in many homes, and neither of them can function without a thermostat. Homeowners with the “if it ain’t broke, don’t fix it” outlook may have perfectly serviceable thermostats that are decades old. But in this age of smartphones and wifi, there’s a lot to be gained in upgrading your thermostat — and who knows, your old faithful thermostat could finally bite the dust.

Diagnosing a Broken Thermostat

The most obvious reason to replace a thermostat is because it’s broken. Thermostat failure can sometimes be tricky to diagnose on your own, because you could also suspect problems with your heating and air conditioning systems. If you don’t have DIY experience with thermostats and HVAC systems, you may need the assistance of a licensed HVAC technician to affirmatively pinpoint the thermostat as the source of your problems.

Some of the most common symptoms of a broken thermostat include:

  • The actual indoor temperature as measured by a separate thermometer is different from the temperature displayed on the thermostat
  • The HVAC system doesn’t turn off when the temperature reaches the thermostat setting
  • The HVAC system doesn’t turn on when the temperature changes from the thermostat setting
  • The thermostat is unresponsive
  • A battery -operated thermostat drains fresh batteries too quickly

Should You Replace Your Manual Thermostat?

Just because your old thermostat works doesn’t mean it isn’t costing you an opportunity to save money. Manual thermostats — whether they’re digital or the old-fashioned analog dial — can only be changed by a person interacting with them directly. But with a programmable thermostat — or better yet, a smart thermostat — you can exert greater control over your thermostat so that you’re not wasting energy maintaining temperatures that no one is home to enjoy.

Advantages of a Programmable Thermostat

Digital programmable thermostats are comparable in price to manual thermostats and offer money-saving features, so there’s no reason not to choose this type as the minimum standard for thermostat replacement. Some features may vary from one programmable thermostat to another, but the primary feature is that these thermostats let you set different temperatures for different days and times. While everyone is at work and school, the thermostat can be set a few degrees lower in the winter and higher in the summer. Over time, the energy savings can more than pay for the cost of the upgrade, all while helping the environment the entire time.

Advantages of a Smart Thermostat

The state-of-the-art option, though, is the smart thermostat. Smart thermostats can be controlled from anywhere in the world via smartphone or tablet apps. These apps make setting schedules easy and elegant, but whenever your plans change, you can take control with a few taps of your phone. There’s an even greater variety of features among smart thermostat brands, such as intuitive technology that “learns” your schedule and settings that respond to outdoor weather conditions.

Which New Thermostat Is Right for You?

Given the unparalleled features of smart thermostats, there are a lot of reasons to go big with your next thermostat upgrade. But smart thermostats aren’t necessarily the perfect fit for everyone. For instance, smart thermostats can’t function without access to wireless Internet, and they’re not practical for homeowners who don’t use smartphones or tablets. So if you don’t have both wireless internet and a smartphone or tablet, you’ll get much more benefit from a programmable thermostat.

Smart thermostats are more expensive than programmable thermostats, and if you pay an HVAC technician to have yours professionally installed, the installation costs could also be higher. It all depends on the existing wiring within your walls.

Another consideration is that smart thermostats aren’t compatible with all heating and cooling systems. If you have central air conditioning and heating or a heat pump, it’s likely that you’ll be able to integrate most smart thermostat models into your home. But if you have radiator heat, baseboard heaters, swamp coolers or other less common components in your HVAC system, there may be compatibility issues. You should check the product specifications of each smart thermostat you’re considering to make sure they’re compatible with the equipment in your home.

All that said, if you’re a smartphone user with wireless internet, a compatible HVAC system and enough money to purchase and install a smart thermostat, the savings potential of this technology is enough to pay for the cost of the upgrade over time.

Ready to replace a thermostat in your home? Choosing the right thermostat isn’t the only big decision — you’ll also need to decide whether to install it yourself or hire a pro, which is what we’ll explore when we return with part two of this project.

About Josh Crank

Josh Crank is a freelance writer and content marketer with a background in legal journalism, travel writing, and marketing for numerous commercial industries. He’s found his perfect fit at Direct Energy in writing about home maintenance and repairs, energy efficiency, and smart home technology. Josh lives with his wife, toddler son and endlessly howling beagle-basset hound mix in New Orleans.

In the market for a new thermostat?

To help you navigate the wide world of thermostats, we’ve created a step-by-step guide to help you choose the right replacement thermostat for your home.

Choosing a replacement thermostat involves 3 easy steps:

  • Choosing the type of thermostat you want
  • Making sure it can work with your home and HVAC equipment
  • Contacting a pro to help you install it

Want to talk to a pro to walk you through the process? Give us a call—we’re happy to help.

Contact us today

Step #1: Choose the type of thermostat you want

We often get this question from Arizona homeowners: “What kind of thermostat do I need?”

In this section, we’ll go into the 3 main types of thermostats, and discuss their pros and cons.

1. Manual thermostats (good)

Also called “mechanical” or “non-programmable” thermostats, manual thermostats are the most basic type of thermostat you can buy. You must manually adjust it to turn your HVAC system on and off and control the temperature.

You can buy 2 types of manual thermostats:

The downside to manual thermostats is that some models aren’t the most precise when it comes to temperature control. In fact, some manual thermostats have about a +/- 3° differential, while other types of thermostats only have a +/- 1° differential.

2. Programmable thermostats (better)

Programmable thermostats do just what their name suggests: they can be programmed to save you money on your energy bills. In fact, according to Energy.gov, programmable thermostats can save you up to $180 per year in lower energy bills.

For example, if you’re at work 5 days a week for 8 hours, that’s 40 hours every week during which you can dial back your AC or heating system to save you money. And sure, you can turn your HVAC system off with a manual thermostat, but that means you’ll always come home to uncomfortable temperatures.

A programmable thermostat solves this issue by telling your HVAC system when to turn on/off and to what temperature, so you don’t have to do it manually.

Here’s how it works:

If you leave the house at 8 am and don’t come back until 6 pm, you can program your thermostat to automatically raise or lower (depending on the season) your home’s temperature by 10° right at 8 am. Then, you can set it to automatically return to comfortable temperatures at 5:30 pm so that the house is comfortable by the time you get home.

3. Smart thermostats (best)

Smart thermostats are programmable thermostats taken to the next level of connectivity and comfort. You can control these thermostats from your computer, tablet or phone which means you can adjust your home’s temperature remotely.

Though they are the most expensive, these thermostats have the best comfort features and also save you money every month on your utility bills.

Some comfort features you can find on smart (and some programmable thermostats) include:

  • Touch screen displays
  • Voice instructions and notifications
  • Dirty air filter alerts
  • Multiple programmable schedules (weekday, weekend, vacation, etc.)
  • Schedule “learning” capabilities (where the thermostat learns your daily schedule automatically instead of you having to program it)

Step #2: Make sure it can work with your home and HVAC system

Once you determine the kind of thermostat you need, you’ll want to be sure that you pick a specific model that’s compatible with your HVAC system.

To make sure a thermostat is compatible with your system, check that it can work with:

  1. Your system’s specific voltage
  2. The location on the wall
  3. The # of heating/cooling stages your system has

Let’s go into more detail about each of these points.

#1: Check your system’s voltage

Your HVAC system either is a low voltage, millivolt or high voltage system. You’ll need to get a thermostat that is compatible with your system’s voltage requirements.

Most thermostats work with low voltage systems. And the good news is, unless you have wall/floor heaters or an electric baseboard heating system, you most likely have a low voltage system because they are the most common.

How to confirm your thermostat works with a low voltage system:

Look at the specs on the thermostat box or manufacturer label. If you’re looking online, look for the words “low voltage,” as seen in the screenshot below:

Screenshot taken from Google Shopping on 01/25/2018.

Note: If you have wall/floor heaters or an electric baseboard heating system, you either have a millivolt or high voltage system, respectively. You’ll want to contact a professional for help choosing a thermostat that works with those systems.

#2: Make sure the thermostat fits on your wall

Don’t forget to verify that the new thermostat will fit in the same location so you don’t have to mess with rewiring. Also, keep in mind that if your home is zoned, each zone has its own thermostat so you’ll need to purchase multiple thermostats.

Not comfortable doing these steps yourself? Contact a professional to make sure your new thermostat is compatible with your system.

#3: Have a pro determine the # of heating/cooling stages your system has

“Stages” refers to how many speeds your AC or heating system can run.

Your HVAC system will fall into 1 of the following categories:

  • 1-stage = the system works at full speed, or off (like an ON/OFF switch)
  • 2-stage = the system works at a LOW or HIGH speed
  • Variable speed = the system can ramp up or down its cooling/heating levels depending on what’s needed at any moment

The bottom line is that you’ll need to confirm that your thermostat’s wiring is compatible with the number of stages your HVAC system has.

Since this step requires you to “read” your current thermostat wiring, it’s best to have a professional handle this for you.

Step #3: Contact an HVAC expert to help you install it

The easiest (and safest) way to install your thermostat is to have a professional do it for you.

An improperly installed thermostat (due to a DIY attempt) can result in:

  • HVAC system malfunctions
  • Lowered comfort (improper wiring can even leave you without cold/warm air)
  • Expensive repairs
  • Unnecessarily high monthly energy bills

Hiring a pro guarantees that your thermostat will work with your system and that you won’t run into any problems down the road.

Need thermostat advice or an install?

Just give us a call. We’d be happy to answer any questions you have or help you schedule an appointment with one of our trusted techs to install a new thermostat for your home.