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What is a smart thermostat?

Smart thermostats explained: How they work and how they save you money

As utility bills continue to rise, many homeowners have turned to smart thermostats as a way to cut their expenses. Not only do they look more elegant and advanced than a standard thermostat, but they come with a variety of powerful features that can help optimize your heating and cooling schedules — and save you a bundle of cash in the process. But what exactly is a smart thermostat, and why should you consider adding one to your home? Here’s a closer look at these versatile gadgets and how they stack up to the competition.

What exactly is a smart thermostat?

A smart thermostat is a thermostat that can be controlled with a phone, tablet, smart speaker, or another internet-connected device. Smart thermostats typically allow you to schedule your desired temperature settings, and you can also incorporate them into home automation systems. They also tend to feature sleek, modern designs — which are a vast improvement over the clunky rectangles offered by traditional thermostats.

What else can a smart thermostat do?

Depending on the specific model, smart thermostats can offer a plethora of cool features. Some thermostats, like the Nest Learning Thermostat, can learn your heating and cooling preferences and automatically adjust based on said learning. Many of the best smart thermostats have diagnostic features, which can detect when there’s a problem with your ductwork or HVAC system. Your smart thermostat may also be able to remind you of when it’s time to perform system maintenance, like when it’s time to change your air filter. Your thermostat may also be able to provide you with details regarding your energy consumption or even give you a reading on your indoor humidity levels.

Some thermostats also include room sensors that can measure the temperature in a specific room or area of the home and heat or cool that room specifically based on the temperature in that local area, reducing hot or cold spots in the home. If your thermostat has geofencing, it can recognize when you enter the home and save on heating and cooling costs when you’re away from home.

How does a smart thermostat work?

Terry Walsh/Digital Trends

To understand how a smart thermostat works, you’ll first need to understand how a regular thermostat works. A thermostat uses temperature to determine when it needs to turn the fan and AC or heat on and off. It actually works kind of like a light switch, except it incorporates temperature into the equation. A typical thermostat has a hot wire, a common wire, a wire that connects to the fan blower, and wires that connect to your HVAC system for heating and cooling. It may also have additional wires for things like auxiliary heat, emergency heat, two-stage heating or cooling, or wires for systems that have separate or standalone AC or heat. When you set a specific temperature on your thermostat, the fan and heating or cooling shut off once the internal thermometer reaches the desired temperature. Here’s how to test your thermostat.

Smart thermostats work similarly, except they also connect to the home’s Wi-Fi. This allows you to change the thermostat’s settings remotely using a companion app. When you input a temperature setting into the app, it transmits that setting through your Wi-Fi network to the thermostat, and the thermostat then sends that signal to the blower and HVAC system. When you use a smart speaker like Google Home and say, “OK Google, set temperature to 70 degrees,” the Google Home app communicates the command to the thermostat’s companion app, which travels through your Wi-Fi network to the thermostat. It all happens so quickly that you’ll probably never notice all of the components involved in simply adjusting the temperature in your home.

How does a smart thermostat save you money?

Smart thermostats save you money simply by cooling and heating the home only as much as needed. Using features like learning, scheduling, geofencing, as well as the ability to diagnose problems with the system and remind you of when it’s time to perform maintenance, your HVAC system runs more efficiently and uses less energy. Room sensors can also reduce energy consumption by heating and cooling specific areas more accurately.

What’s the difference between a smart thermostat and a programmable thermostat?

A programmable thermostat allows the user to input schedule and program settings. A smart thermostat is a step up from a programmable thermostat, as it typically allows the user to program desired settings and it connects to Wi-Fi for more advanced features and functionality. In other words, smart thermostats make it easier to program schedules or adjust the temperature, as you can access your thermostat remotely from a smartphone app or other device.

What are the requirements for installing a smart thermostat?

Most homes with modern HVAC systems can upgrade to a smart thermostat, provided there’s a Wi-Fi connection. However, given that there are a variety of different types of heating and cooling setups, it’s prudent to confirm your system’s compatibility before purchasing a smart thermostat. You may also need a C-wire (or common wire) in your existing thermostat’s wiring setup. If you don’t have a C-wire, you can purchase a smart thermostat that includes an adapter kit.

Adapter kits can be installed by anyone, although they do require a bit of rewiring. If you’re uncomfortable opening up your furnace and tinkering with cables, consider contacting a professional for assistance or opting for a smart thermostat that doesn’t need a C-wire.

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Erika Rawes
Smart Home Evergreen Coordinator
Erika became a professional writer in 2010, and her work is published all over the web on sites ranging from USA Today to…
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