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Best smart thermostats of 2021

We tested smart thermostats from Amazon, Ecobee, Honeywell, Nest and more. Here's what you need to know.

smart thermostat is an app-enabled device that does more than manage your home's heating and cooling system. You can adjust your thermostat remotely anywhere your phone has a Wi-Fi or cellular connection. That way, you can manage your heat and AC whether you're at the grocery store, on vacation -- or just hanging out at home. Many models can also be controlled via SiriAlexa or Google Assistant voice commands.

Some smart thermostats also use occupancy sensors to determine if you're home or away to automatically change the temperature for you. Other thermostats automatically switch between home and away mode based on your phone's location. Some even employ remote temperature and proximity sensors to extend the detection range of your thermostat to other parts of your home. 

To accompany these modern features, many connected thermostats offer innovative designs. From a rounded shape to a responsive touchscreen, smart thermostats look a lot different than traditional models. They can also send you smart alerts, sync with the rest of your smart home devices and provide details on your HVAC system's energy usage over time.

Without further ado, let's explore the best smart thermostats.

Chris Monroe/CNET

The $60 Amazon Smart Thermostat is the least expensive smart thermostat I've tested. It works via the Alexa app and with Alexa voice commands. You need a compatible Alexa-enabled smart speaker or display to use voice commands, but you don't have to enable an Alexa skill since this is an Amazon-branded product.

This thermostat also looks nice. It has a simple, modern design and an optional wall plate if you need to cover any old paint or holes. The touchscreen interface is minimal, but makes it easy to adjust thermostat and switch among heat, air conditioning and other basic settings. 

The Amazon Smart Thermostat isn't compatible with Google Assistant or Apple HomeKit and there's no remote temperature sensor accessory. You also either need a C-wire or you have to buy and install the C-wire adapter.

This is a solid product overall, but ultimately its amazing value is what sets it apart and makes it our current favorite. Read our Amazon Smart Thermostat review.

Chris Monroe/CNET

At $249, the Ecobee SmartThermostat with Voice Control is expensive, but it has the performance and features to back it up -- especially if you want to talk to Alexa without having to buy an Amazon Echo. This model also works with Google Assistant and Apple HomeKit, as well as Spotify. If you want a connected thermostat, Ecobee's SmartThermostat with Voice Control is the smartest around.

Read our Ecobee SmartThermostat with Voice Control review.

 

Chris Monroe/CNET

The Honeywell Home T9 is a $200 smart thermostat from Resideo. The T9 works with Alexa, Google Assistant and Apple HomeKit and offers reliable performance and a solid app. The device also comes with remote humidity, proximity and temperature sensors, making it the smartest sensor accessory around. Nest's sensor only provides ambient temperature readings, while Ecobee's sensor only has temperature and proximity detection capabilities.

Read our Resideo Honeywell Home T9 Smart Thermostat review.

 

Tyler Lizenby/CNET

I hold that the $249 Nest Learning Thermostat is still the best-looking smart thermostat out there. Its rounded design harkens back to old-school thermostats, but the device has a modern look that fits in with nearly any home decor. The $169 Nest Thermostat E looks nice too, but it has more plastic components that aren't as appealing as the Learning Thermostat's stainless steel.

Read our Nest Learning Thermostat Third Generation review.

 

Smart thermostat FAQs

What is the most reliable smart thermostat?

Since thermostat performance can vary based on different HVAC systems, electrical wiring and other factors, I can't definitively say one particular model is more reliable than any other. 

I can say that the four smart thermostats I recommend above -- the Amazon Smart Thermostat, the Ecobee SmartThermostat with Voice Control, the Resideo Honeywell Home T9 and the Nest Learning Thermostat -- all performed reliably during my testing.

By that I mean, each of those smart thermostats consistently adjusted the temperature, setting and mode as expected over the days I tested them. Always check with a professional electrician if you have any questions about your HVAC system's compatibility with a particular thermostat before you install it.  

Are smart thermostats really worth it?

Whether a smart thermostat is worth it or not depends on how you use it -- and what exactly you mean by "worth it."

Smart thermostats make it easier to use less energy and save money because of their advanced features, but you have to take advantage of those features in order to see a benefit. 

Options like automatic home/away modes based on your phone's location -- or sensors in the thermostat and in remote accessories that detect proximity -- can go a long way toward reducing your monthly bill. In addition, if you take the time to review the energy usage reports smart thermostat companies provide, you'll be able to identify patterns and potentially save even more money.

But smart thermostats are also more expensive than standard non-smart models. So, you have to think long-term when it comes to savings. It could take a year or more to start saving more than you spent on a smart thermostat, especially a $250 model like the Nest Learning Thermostat or the Ecobee SmartThermostat with Voice Control. 

How do I install a smart thermostat?

How to install a smart thermostat can vary widely depending on your HVAC system. Hire a professional electrician to handle the installation or to answer any questions before you attempt the installation yourself.

That said, all of the smart thermostats I've tested follow a pretty consistent step-by-step process. If you're comfortable with basic electrical work and know whether your system is compatible with the specific model you want to buy, it's a simple DIY process.

Check out my article about how to install the Nest Thermostat for a basic overview of the steps, but remember it could vary based on the system you have at home. 

Testing a thermostat

Let's talk about testing. Smart thermostats start with the installation. Installations can vary widely from thermostat to thermostat and between HVAC systems, but there are some basic steps required for installing these devices. As always, consult a professional installer if you have any questions about the setup process. Here are the general steps:

  • Turn off power to your thermostat at the circuit breaker
  • Remove the old thermostat
  • Install the thermostat's base plate with the included screws
  • Attach the wires to the wire terminals 
  • Snap on the faceplate
  • Turn on power at the circuit breaker

Was the thermostat setup especially difficult to install? If so, why? Certain models require a C-wire, for example, which can complicate the installation if you don't have one. Not sure what a C-wire is? Start here

From there, I move on to the app. Every smart thermostat has one. I download the app and create an account if I don't already have one. Then I configure the thermostat following the steps in the app. This usually means connecting to the local Wi-Fi network, giving your thermostat a name like "Hallway" or "Bedroom" and then you can start using your thermostat.

How well does the app work? Is it easy to navigate to the thermostat settings you need? Is it simple to create a schedule or enable geofencing? This factors into the thermostat's usability score, along with how simple the thermostat hardware itself is to control manually. 

I also test smart home integration, especially voice-enabled systems you can access through voice assistants like Alexa, Google Assistant or Siri. Most connected thermostats have compatibility with at least one voice assistant and some work with all three. Do the voice commands flow naturally, like they would in an actual conversation? Did the thermostat actually adjust the temperature -- heating and cooling -- according to your commands? 

All of these things determine a smart thermostat's overall score and how likely I am to recommend it. Here's a running list of the models we've tested lately:

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