As chilly days and evenings settle over Santa Fe and Albuquerque, home heaters are firing often. Once you set your thermostat (the main interface between you and your HVAC system), you likely assume it’s guiding your heating system to warm your home to the set temperature. It may not be. Thermostats can lose calibration over time from being accidentally bumped or from dirt accumulating.

An improperly calibrated thermostat can cause discomfort because it’s not heating your home accurately. It can also cause your HVAC system to work inefficiently, which leads to greater costs and more wear and tear on your unit. As with all aspects of your HVAC system, thermostats require occasional maintenance and, if needed, repairs to keep them working accurately and efficiently. Read on to discover everything you need to know about calibrating your thermostat yourself — and when to call in a professional service such as Aztec Mechanical.

How to Check Thermostat Calibration

Whether your home has a manual, programmable, or smart thermostat, ensuring you have a properly working system starts with checking thermostat calibration. You should plan to perform this test at least once a year; we recommend conducting it in the fall. If you have a programmable or smart thermostat, perform the test at set points for when your home is occupied and unoccupied. This will ensure the thermostat is regulating properly through these automated functions.

To conduct the test, tape or place an accurate thermometer near the wall thermostat. Wait at least 15 minutes, then check the readings on both devices. If they match, your thermostat is calibrated accurately, and you don’t need to take further action. If the readings vary more than a few degrees, it’s time to troubleshoot. If you don’t feel comfortable conducting any of the following maintenance, it’s time to call in a professional.

Easy Maintenance: Clean the Thermostat

Over time, dust can accumulate in your thermostat. This is particularly true in New Mexico! Dust in the unit can cause it to malfunction and not provide accurate readings.

Carefully remove the cover and gently brush away dust or dirt. Many homeowners and commercial property owners use a soft cloth or Q-tip. When cleaning the coils, grab a new dollar. The thin, and soft yet slightly abrasive texture will allow you to easily slide it between coils or pluck debris off the coils. Don’t use sandpaper or emery cloth; these are too abrasive. Vacuum cleaners are also too powerful for this delicate work, so don’t use one. You may accidentally disrupt wire connections.

Easy Maintenance: Straighten the Mercury Vial

If your thermostat continues to measure inaccurately, make sure the mercury vial is straight. Using a level and your hands, adjust the vial with your fingers. Keep in mind that the mercury inside should never touch your skin. It’s a gentle operation! If you’re concerned about this, contact Aztec Mechanical to help.

Easy Maintenance: Tighten the Calibration Screw

If none of the above steps have worked — or you don’t have a mercury vial in your unit — adjust the connections via the calibration screw. It’s located inside a curled piece of metal inside the thermostat. Using an appropriately sized screwdriver, turn the calibration screw to open the contacts. Wait a few seconds, then turn the screw to close the contacts. This will reset the contacts and make sure a bad connection wasn’t causing your thermostat to become uncalibrated.

Repair: Recalibrate the Thermostat

If further tests show your thermostat still isn’t reading accurately, you may need to recalibrate it. Different thermostat models have different procedures, so consult your owner’s manual for a step-by-step guide to recalibration. The process has a few universal steps, including determining the temperature difference needed for adjustment, accessing the calibration settings on your thermostat, adjusting the calibration, and exiting the function. Once complete, you should retest the thermostat against your thermometer to ensure you’re now getting an accurate reading. If you’re not, or if any of the steps above fail, it’s time to call in a professional.

How Aztec Mechanical Can Help

As full-service HVAC experts for home and commercial properties, Aztec Mechanical can ensure your heating system is working safely and efficiently. Contact us to get started today.