What Happens If My Smart Thermostat Stops Working?

By Craig Lloyd on February 4th, 2017

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Many people might feel a bit wary installing a smart thermostat in their home, considering how often modern technology screws up. But don’t worry, manufacturers have thought of that: here’s what happens if your smart thermostat ever stops working.

Thermostats are one of the most important devices in your house, as they regulate the indoor temperature so that it doesn’t get too cold or too hot. This isn’t just for your comfort, but also so that your water pipes don’t freeze during the winter and cause an even bigger problem.

Many fear that smart thermostats are a disaster waiting to happen, whether it’s the internet going down or the thermostat itself glitching out. However, there’s really not too much to worry about. Here are some things to keep in mind if something should ever happen.

If Your Internet Goes Down

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Some homeowners think that if your internet goes down, then you won’t be able to adjust the temperature on a smart thermostat. In reality, when smart thermostats lose their internet connection, they simply act as a normal thermostat—the only functionality they lose is the ability to control them from your smartphone.

That means if you’re on vacation and your home internet goes down, the thermostat won’t fail. You just won’t be able to check on your home’s temperature from afar. Whatever you had the thermostat set to when the internet went down is what it will stay at, unless you have a schedule set up, in which case the thermostat will continue to abide even if it’s not connected to the internet.

If the Power Goes Out

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When the power goes out at your house, a smart thermostat isn’t any worse off than a dumb thermostat—neither will work if the power goes out.

Unless your HVAC system has some kind of power backup that it can use, your thermostat will be useless during a power outage, whether it’s smart or not. This is why it’s always important to have a propane-powered heater available during the winter whenever the power goes out. Or if you have a fireplace, make sure it’s ready to go and you have a stockpile of wood available.

Your thermostat might have a battery backup, but that’s simply to keep the memory saved. So if you have it programmed and on a schedule, the battery would keep the memory from getting wiped. Your HVAC system itself would still need its own backup power in order to use the entire system during a power outage. Dumb thermostats don’t make this any better.

If Your Smart Thermostat Completely Fails

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Any thermostat, smart or dumb, can fail at any time. Even mechanical thermostats that completely rely on analog technology can still malfunction (although there’s a less of a chance of that happening). If a smart thermostat ever goes offline, it can at least send you a notification warning you (though that’s not 100% reliable either).

There have been plenty of horror stories about smart thermostats completely failing and letting homes get way too cold, resulting in burst water pipes and causing thousands of dollars in damage.

There’s not a whole lot you can do to keep a thermostat from failing, but wiring in a second thermostat as a failsafe can make for a great backup. Basically, you would connect a cheap, mechanical thermostat in between your main thermostat and the HVAC circuit board. From there, set it to a low, but safe temperature like 50F. Then, if your smart thermostat ever did crap out, the backup thermostat would kick in once the indoor temperature reached 50F.

Some newer HVAC systems come with failsafes built in, but they’re not incredibly common, so if you have the knowledge and know-how, wiring in a backup thermostat is never a bad idea—it’s good to have one even if you don’t use a smart thermostat.

Craig Lloyd writes about smarthome for How-To Geek, and is an aspiring handyman who loves tinkering with anything and everything around the house. He's also a mediocre gamer, aviation geek, baseball fan, motorcyclist, and proud introvert.

  • Published 02/4/17
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