Line voltage or low voltage: What thermostat do you need?

The back of a Honeywell low-voltage thermostat, left, and a Cadet line voltage thermostat.
The back of a Honeywell low-voltage thermostat, left, and a Cadet line voltage thermostat. Take note of the different size of wires between the two types of thermostats. Line-voltage thermostats have much thicker wires.

We hear a lot of questions from customers about thermostats. One of the most frequently asked ones is: “Do I need a low voltage or line voltage thermostat?”

Here’s a quick guide to help you find the answer.

Line voltage thermostats
Line voltage thermostats are typically used for radiant, convection or resistance heaters that are powered by electricity. They’re the type of thermostats to use with our baseboard and wall heaters. Also, you will use a line voltage stat for cove heaters and in-ceiling radiant heat.

If you’re replacing a thermostat in your home, one of the best ways to find out which one you need is to check your wiring. Line-voltage units have two or four thick wires coming out of the back that are attached with wire nuts to wires in the wall. (Sometimes the thermostats are attached to the heater themselves.)

Line voltage thermostats typically have two or four wires coming out of the back of them, which are much larger than the wires you'll see on low-voltage thermostats.
Line-voltage thermostats typically have two or four wires coming out of the back of them, which are much larger than the wires you’ll see on low-voltage thermostats.

Low voltage thermostats
Low voltage thermostats are more common across the country. These thermostats are used with central heating systems including furnaces, boilers, air conditioning, heat pumps and split systems. The giveaway for these types of stats is that they have multiple wires going into them and the wires aren’t as thick as you’ll find on line-voltage stats.

low-voltage thermostat back
Low-voltage thermostats, like this Honeywell Lyric, have a variety of small wires connected to the back.

So here’s the rundown if you’re looking for a thermostat: if you’re using our products or other radiant heat in your home, you’ll probably need a line voltage thermostat. If you’re using a central system, you’ll want a low voltage one.

Or — maybe you’ll have both in your home. There’s no rule against using baseboard or wall heaters to complement a central system by warming up a  in a cold room or basement.

 

Paul Suarez

Paul Suarez

Paul is a highly caffeinated, uber organized family man that keeps himself busy finding and sharing the stories that make Cadet a great company. When he isn't writing, or shooting photos and videos, you'll likely find him searching for killer deals on Craigslist, playing classic Nintendo games or quoting his favorite movies and TV shows.

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