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Which smart thermostat is right for you? With choices from Amazon, Ecobee, Honeywell, Nest and more, there are more options than ever before.

Megan Wollerton has covered technology for CNET since 2013. Before that, she wrote for NBC's Dvice.com (now SyFy). Megan has a master's degree from the University of Louisville and a bachelor's degree from Connecticut College, both in international relations. She is a board member of the Louisville chapter of the Society of Professional Journalists. When Megan isn't writing, she's planning far-flung adventures.

A smart thermostat  does more than just manage your home's heating and cooling: It's an app-enabled device that comes with tons of different features. It allows you to control your home's temperature from anywhere, whether you want to turn on the heat on before your commute home from the office from a vacation spot halfway across the world. And because it's a smart device, many leading thermostats can be controlled using a compatible smart display  or speaker  using voice commands through Alexa , Google Assistant  or Siri .

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 modes 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 other connected devices in your home and provide details on your HVAC system's energy usage over time.

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

The 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 is Energy Star-certified, saving an average of $50 on a yearly energy bill. 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 the 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.

With a list price of $250, the Ecobee Smart Thermostat Premium is expensive, arguably too expensive given the current trend of more affordable models out there. Still, this model has a lot to recommend it, especially if you want to talk to Alexa without having to buy an Alexa speaker or display. This model also works with Google Assistant and Apple HomeKit, as well as Spotify. If you want a connected thermostat, Ecobee's Smart Thermostat Premium is the smartest around.

Read our Ecobee Smart Thermostat Premium review.

The Honeywell Home T9 is a $200 Wi-Fi thermostat with a touchscreen and one smart room sensor. 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.

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.

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 Smart Thermostat Premium, 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.

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 Smart Thermostat Premium.

Smart thermostats can handle a lot of the heavy lifting for you, but you also have to put in some effort. Make sure to answer all of the questions when you configure your thermostat. Most likely you'll be asked to set minimum and maximum temperatures, comfortable temperature ranges when you're home and away and more.

The more details you can provide, the better chance you have of actually saving money with a smart thermostat. 

How to install a smart thermostat can vary widely depending on your HVAC system. You can 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. 

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:

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: