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How To Calibrate Your Thermostat Properly

You can set the thermostat in your home or office on the perfect temperature – whatever that means to you personally – but how do you guarantee that the thermostat is reading the room’s temperature correctly?

If the thermostat isn’t calibrated correctly, you could still find yourself uncomfortable with the indoor temperature, and even more alarming, you could be driving your cooling costs way up trying to find the perfect temperature to set the thermostat.

Your thermostat can lose its calibration if dirt gets inside it or if it gets bumped. The result is that you may set it on 75, but it will only cool the room to 78. Constantly readjusting the thermostat can raise your utility bill by up to 10 percent. The same is true for an incorrectly calibrated thermostat that thinks it’s running at a lower temperature than it actually is.

Calibrating your thermostat can be done easily by a general contractor, air conditioning pros like ABC Home & Commercial Services, or you can do it yourself. We’ve explained the steps below.

Check The Thermostat’s Accuracy

Tape a glass thermometer to the wall. Be sure that the thermometer isn’t touching the wall. You can put paper towels behind it to keep this from happening. Let the air condition work for about 15 minutes, and then compare the temperature reading of the thermostat and the thermometer. If the reading is more than 1 degree off what your thermostat is, you should keep reading.

If there’s no difference, your thermostat is properly calibrated. It’s a good practice to do this at least every month during the summertime, just to make sure you aren’t losing efficiency.

Clean The Inside…Gently!

First, remove the thermostat cover and clean the inside. They all look a little different, so proceed with caution. Use soft brushes or cloths to clean the components, especially delicate coils. Some people find that a new dollar bill works well for cleaning between magnetic connections since it is soft yet slightly abrasive and very thin.

Don’t use a vacuum cleaner for this, since their suction can be too strong for the delicate parts inside. And if something is broken inside, you don’t want to suck it up into the vacuum’s reservoir, no matter what type it is.

Straighten The Mercury Vial

If your thermostat is equipped with a mercury vial, make sure that it is completely straight. This may require using a level. You should be able to adjust the vial with your fingers, but remember that there’s actual mercury inside, which should never come in contact with your skin. Be extremely careful!

If you get this far and realize that your thermostat has a mercury vial, it’s perfectly ok to stop right there and call a professional. There’s no reason to put yourself or your loved ones in danger.

Or, Tighten The Calibration Screw

Instead of a mercury vial, your thermostat may have a calibration screw instead. It will be located inside a curled piece of metal within the thermostat. Once you’ve located it, determine the size screwdriver you will need. Don’t use anything besides a screwdriver to turn the calibration screw.

Using an appropriate-sized screwdriver, turn the screw back and forth slowly until the contacts open. Wait a few seconds and turn the calibration screw until the contacts close again. This simply resets the contacts, making sure that there wasn’t a bad connection between them, causing your thermostat to become uncalibrated.

Check All The Wiring Connections

Just to be sure, while you’re inside the thermostat you can check to see if all the wiring is connected securely. Dirt and corrosion are big problems for wiring and connections. You can remove any signs of corrosion at the connection sites with a cotton swab, then check them again before you close up the thermostat.

Re-Check The Temperature

Repeat the first step, checking the temperature with a glass thermometer again. Remember to give the thermostat about 15 minutes before taking your final reading. Hopefully, these simple steps will fix your thermostat calibration issue.

If you follow these steps to the letter and you still see a difference of more than 1 degree between your thermostat and the thermometer, some bigger problem may be preventing your thermostat from calibrating.

At this point, the best thing to do is call in an expert like ABC Home & Commercial Services before the summer’s hottest temperatures get here! A professional can evaluate your entire air conditioning system to see where the problem is.

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