You shouldn't need to calibrate a programmable thermostat too often, but occasionally, your system might be a little off. Your thermostat works by sensing the temperature in your home and sending a signal to your HVAC system to start running. If the sensor is off, your home won't be as warm or cool as you want it to be. Calibrating the thermostat can adjust it to make it more accurate.
Reasons to Calibrate a Thermostat
Most programmable thermostats come already calibrated from the manufacturer, and you don't need to calibrate them again. Some situations can cause the thermostat to lose its calibration, though. One example is too much dust in the thermostat. Some can lose calibration if they get bumped or lose power.
Checking the Calibration
Before you start adjusting your programmable thermostat's settings, verify that there's a calibration issue. You can do this simply with a household thermometer that you know is accurate. Place the thermometer or its sensor as close to the thermostat as possible since there can be temperature fluctuations throughout your house. Wait at least 15 minutes and check for a difference between the thermostat and your thermometer. If it's more than a few degrees different, calibrating your thermostat can help it work more accurately.
Cleaning the Thermostat
Cleaning the thermostat might help with the calibration. Remove the cover and gently use a soft brush, cotton swab or compressed air on the contact points and internal parts. Replace the cover and check the calibration again with your thermometer.
Calibrate a Programmable Thermostat
Keep in mind that every programmable thermostat will be slightly different in its controls and how you calibrate it. The difference is often in how you access the calibration option from the programmable keypad. Refer to your owner's manual to determine how you can reach the calibration adjustment option.
Step 1: Determine the Temperature Difference
Calculate the difference in temperature readings between the thermostat and thermometer. You need to know the number of degrees and if the thermostat is higher or lower than the actual temperature. If your thermostat says it's 70 degrees Fahrenheit but your thermometer reads 73 degrees, the thermostat is reading 3 degrees lower than the actual temperature.
Step 2: Access the Calibration Setting
Enter the calibration mode based on your thermostat's instructions. For example, on some Lux thermostat models, you turn the thermostat to "off" and hold the up and down buttons simultaneously until a number displays on the screen. On other Lux models, you press "menu," scroll to "set review swing value," press "ok," press "next" to skip swing and press "next" again to skip offset to reach "adjust value cal." Other brands and models might have different steps or buttons to push.
Step 3: Adjust the Calibration
Press the up and down arrows to adjust the temperature change based on your calculations. You can adjust it to negative and positive numbers. If you choose a negative number, it lowers the temperature show on the screen. If you adjust it to -3, it will lower what the screen reads by 3 degrees. If it previously read 70 degrees, it will now read 67 degrees. If you choose +3, it would change the display to 73 degrees.
Step 4: Exit the Calibration Setting
Go back to the main screen on your programmable thermostat. Look for an "exit" or "back" button that returns you to the main screen.
Step 5: Recheck the Calibration
Use the same thermometer you used previously to see if the calibration worked. Wait at least 15 minutes and see if the thermostat and thermometer have the same readings. Continue adjusting the calibration if needed to get the thermostat where you want it.
Shelley Frost combines her love of DIY and writing in her freelance career. She has first-hand experience with tiling, painting, refinishing hardwood floors, installing lighting, roofing and many other home improvement projects. She keeps her DIY skills fresh with regular projects around the house and extensive writing work on the topic.