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How to test a thermostat and save a buck on repair costs

Do you know how to test your thermostat? 

It can really be a drag if your HVAC system isn’t circulating the right air temperature. Hot air when you’re already trying to avoid the sleep sweats simply will not work for most folks. It’d be ridiculous to ignore it and rely instead on your bedsheet’s cooling materials to get you through the night. But hold on before calling in the repair squad — turns out there are few things you can check yourself. Come learn the ins and outs of testing your own home thermostat:

First things first: Is your switch set accurately to cooling or heating? A quick change of direction may be all that’s needed in this situation.  Flip it to the other side and see if that helps.

Check batteries. If any element of your HVAC runs on batteries, it’s best to check those now, if you haven’t already. It can save you time and a little embarrassment later.

Is your air conditioning or furnace not turning on? This is probably one for the repairman, as it’s likely a wiring issue or something wrong with the unit itself — but give it a quick flip on and off just to see if it works first. 

Is your thermostat in a good spot? Placing it near cold, drafty windows or in direct, hot, beaming sun may cause erroneous readings and other issues. 

Is your HVAC system running constantly without stopping at the assigned temperatures? This is likely a wiring issue, best handled by a professional unless you’ve done it before yourself. 

What type of thermostat do you have? If it’s programmable, see if it’s allowing the settings you’re programming in, i.e. temperature. If not, why not? Are you entering them correctly according to unit instructions?

Other issues besides the above-mentioned are probably due to wiring, and best left to the pros unless you’ve got experience:

  • Thermostat is entirely without power; this could be due to bad batteries or something else. Run a test for clues.
  • The furnace or air conditioner won’t turn on, even though it looks like there’s power reaching it. While there may be an issue with the unit itself, it’s also possible there’s a thermostat wiring defect.
  • There’s no evident change in your home’s temperature after you adjust the temperature setting, or the setting and the temp don’t match up.

Follow these basic steps to test your thermostat:

If you have a smart system, maneuver through your settings to find Test. Read and follow the instructions for the test, and run it!

For standard thermostats, have someone help you. Ask them to stand by the furnace while you stand by the thermostat. When you turn the thermostat on to heat, see if your helper also feels warmth coming from the furnace. While you’re turning the heat up to higher temperatures, both the furnace and the thermostat should make a clicking type sound — not just one or the other. If one doesn’t make a sound, look within that unit for the problem. (*If you don’t have a partner to help you, try using a walkie-talkie with the speaker button taped down, or a cell phone, or even a baby monitor with two units — anything that allows you to hear what the other person would hear standing close to the furnace).

Older mechanical thermostats may gather more than their fair share of dust over time. Give it a thorough dusting both in and out by removing the cover and clearing out debris with a cloth.

Replace batteries in any units powered by battery; switch these out regularly, or at least on a yearly basis.

If you find it’s time to get a new thermostat, you’ll have plenty of choices. To save a buck, the U.S. Department of Energy recommends setting a programmable thermostat down by around seven to 10 degrees for eight hours per day. This would be the time most folks are out at work or school, but it can also be the time you’re up and most active, and can easily throw on a sweater (or on warmer, air-conditioned days, you can wear a lighter shirt or tank top). Doing so will save you up to 10% annually on your utility bill.

You can also choose a smart or manual thermostat, with each type having its advantages and disadvantages. If you need more information on energy-saving or thermostats, try our section on household thermostats, energy saving in garages and other workspaces, and more.

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