How To Test A Home Thermostat?

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If your thermostat does not appear to be working, when the summer or winter comes along, you might have some serious problems. Maybe your heater is failing to turn on during the winter or your air conditioning does not come on during the summer.

Not only is this uncomfortable and potentially even dangerous, but it might cost you a lot of money to repair. However, it might not be your furnace or air conditioning system that does not work, but the thermostat itself.

The thermostat might not be sending out a signal as it should, or the thermometer on it may be broken as well. More often than not, the issue is going to lay with your thermostat, not the heating or cooling system, which is thankful because it’s much cheaper to repair than a furnace or AC.

 Let’s figure out how to test a home thermostat so you can get back to living in comfort and hopefully save a bit of cash too.

How To Test A Home Thermostat Thermometer

Ok, so the problem with your thermostat may rest with the thermometer itself. In other words, the thermostat thermometer is registering a different temperature than what it actually is, and therefore it is causing your thermostat to not send a signal to your heating or air conditioning units.

This means that you need to test to see if the thermometer itself is actually working or not. Let’s figure out how to do this right now in a simple step by step manner.

  • Tape a piece of thick paper towel to the wall beside the thermostat, and then tape a normal household thermometer, one that is properly calibrated, to the paper towel. You want there to be paper towel between the wall and the thermometer, so that the thermometer reads the ambient air temperature, not the temperature of the wall.
  • Leave the thermometer taped to the wall for about 15 minutes and then take a reading. If the household thermometer and the thermostat are providing you with different temperature readouts, then you have a problem with your thermostat, and will need to perform a bit of maintenance. However, leave the thermometer and paper towel taped to the wall for the maintenance and testing process.
  • Go to your fuse box or breaker box and shut the power to the thermostat off. Go to the thermostat and ensure that it is indeed not receiving any power, just so you can accurately fix and test it without any risk to yourself.
  • Now you want to clean the thermostat. To do this, remove the cover of the thermostat and use pressurized air to clean the various components. You will also want to use a good piece of tape or even a $10 bill and get in between the contact points of the thermostat, just to ensure that there is no debris in between the contact points.
  • Now you can turn the power to the thermostat back on and repeat the test with the household thermometer and the paper towel. The readings on the thermometer and the thermostat should now be the same. If the thermostat is still not providing you with a correct temperature reading, you may need to replace the batteries in the thermostat. Make sure to use the correct batteries, and once they have been replaced, repeat the thermometer test one more time.
  • If the problem persists, you may not have a problem with the thermometer in the thermostat. It could be that the heat anticipator is no longer working properly. The heat anticipator is the item which shuts the thermostat off when the proper temperature has been reached or turns it on when the temperature gets too low.
  • Sometimes a thermostat may not read the temperature properly because this heat anticipator is loose. In other words, over time, the screws holding everything in place may come loose, and this will then affect the readings and the function of the thermostat. Get a screwdriver and make sure to tighten all screws so the thermostat is completely level and secure against the wall. This should in all reality fix the problem.
  • If you still have an issue, it may be that the thermostat is not sending a signal to the furnace or AC unit, which requires a different solution. To test to see if the thermostat is sending a signal to your furnace, you need to remove the thermostat cover to expose the wiring. Turn the breaker to the furnace off.
  • Untwist the “R” and “W” wires, take them out of their connecters, and then twist the ends of the wires together. Now turn the breaker to the furnace on. If the turns on, it means that the thermostat is not sending a signal to the furnace. Keep in mind that if the furnace does not turn on, it is a problem with the furnace.
  • If you are still having problems at this point, you may need to hire a professional to do some electrical repairs, or you may need to just purchase a new thermostat.


No, living in the cold or extreme heat is not fun, and this means that you need a thermostat that is doing its job. If your thermostat is broken or needs testing, the above steps should get the job done, and if all else fails, you might just need a new thermostat.

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