How to Check Smart Thermostat Compatibility in your Home

So you want to get yourself a smart thermostat. Good for you. It's a smart investment. But, yeah. There are wires involved. And just a little bit of electricity. Nothing too scary (and nothing too high-voltage), but that does mean there's going to be a little bit of homework before you buy. Because (and I know this from experience) there's nothing worse than coming home with a few hundred bucks worth of hardware and finding you can't use it.

The good news is you don't have to be like me. The good news is that it's pretty easy to check to see if your home setup is compatible with a smart thermostat.

I'm not actually going to tell you if your home is compatible, though. But I will show you where to get started. Teach a man to fish, and all that.

Here's how.

First things first: Open things up

Regardless of which brand of smart thermostat you're going to go with, you're going to have to open up your current one and take a look at the wiring.

Most likely you'll see a rat's nest of different colored wires, probably with letters at the terminals. That's a good thing. Go ahead and take a picture of it with your phone. You'll thank me later.

Then, it's time to take a look at what you're considering.

Will my home work with a Nest Thermostat?

Nest installation

Nest does a really good job of walking you through setup once you have one of its thermostats, but it also has one of the best pre-purchase experiences, too.

It's the same basic process. Take a look at your existing wiring, and answer a few questions in an online widget compatibility thing. It's simple enough.

But if you do need some extra help, Nest has additional options to figure things out. It's got an online chat, toll-free phone number, and community forums. Or if you're ready to throw in the towel and just get the thing done, they can hook you up with a "Nest Pro" for professional installation.

Click here to see if your home is compatible with a Nest Thermostat

Will my home work with an ecobee thermostat?

Ecobee install

ecobee also has an decent online installation guide. Its compatibility checker maybe isn't quite as sexy or comprehensive as what Nest has, but the premise is the same. Take a look at your existing wires and run through the guide, and you'll quickly see if it'll work.

ecobee has a couple extra steps — you might need the included power extender kit, or you might not, and it's got external sensors to set up as well.

But ecobee also has an excellent series of videos walking you through things.

Click here to see if your home is compatible with ecobee (opens in new tab)

Will my home work with a Honeywell thermostat?

Honeywell install

Honeywell has the most simple support pages of the three we're looking at here. It's definitely less interactive, but it'll still get the job done.

Again, look at your existing wiring, then run through their little series of questions.

Click here to see if your home is compatible with Honeywell{.cta.large}

Phil Nickinson
  • Sensi is a good option for those without a C wire and not wanting to add one (the most common reason that your setup isn't directly compatible).
  • When I installed my Ecobee thermostat I had an error despite hooking it up the way I thought it was supposed to be. I called tech support, sent them a picture of the old setup (they recommend doing this in their instructions) and within a minute had an answer on how to wire it up correctly. So it might be possible to take a picture of your current wiring and call tech support to check for compatibility before purchasing. Just a thought.
  • No, not really. I have a high tech mercury switch and a bi-metal strip that work very well. It saves me money by turning my gas furnace on and off just like it always has. Every time I realize it's still working, I save over $100 by not purchasing a tech gadget that does the same thing.
  • Be careful...many systems might have multiple wires in the wall, but their current thermostat is only connected by 2 wires. If your current thermostat is connected by only 2-wires regardless of how many are actually coming out of the wall, your system is NOT compatible with ANY of these smart thermostats. Smart thermostats rely on the age-old ANALOG AC management systems...2-wire systems are DIGITAL, serial thermostat interfaces used in the latest generation AC/Heat units that have been offered for the last 10 years or so...think Bryant Evolution/Carrier Infinity solutions.
  • Bryant/Carrier can be rewired at the air handler to use the old analog connections. You can't use both at the same time. This requires opening up a panel on the air handler and disconnecting the serial connection and finding the old analog connection and rewiring.
  • I installed a Nest E thermostat at our lake house. Ended up that it was not working correctly on the first day. Determined that the battery was not charging. I added a common wire and all is well. My wife and I love it! I have the thermostat set to 50° during the week when we are not there. I turn the heat up during the day on Friday from my smartphone and the house is all warmed up when we get therw Friday evening. I know a simple programmable thermostat would take care of turning it up but if we miss a weekend I don't have to waste energy by allowing the heat to run with no one there. I can also check to see how much the heat is running during the week and I get monthly usage emails. Also reminds me via the app on my phone to replace the filter. Been a very useful tool for me this winter. Where I live the gas and electric company offers a rebate that almost pays for the thermostat.