Temperature inaccuracies in your thermostat interfere with your HVAC system cycling. This not only makes it difficult to maintain your comfort level, it can increase the system's energy consumption or eventually cause an unexpected component breakdown or failure. Here are some possible causes of an incorrect thermostat temperature reading and what you can do:
Sometimes, the sensor inside a thermostat malfunctions. You may be able to get it operating correctly by recalibrating the unit, but if there's no improvement in its temperature reading capabilities, it's time to replace it.
Position Shift/Off Level
Older mercury thermostats need to sit level to function accurately. If yours was bumped and looks off level, try putting a regular carpenter's level above it as a guide to reposition it. If this doesn't work, you should take the opportunity to buy a new, modern thermostat.
The thermostat needs to be in the right location to read and control your indoor temperature correctly. Make sure yours is centrally situated, and away from anything that can alter how it functions. It shouldn't be in direct sunlight or exposed to drafts, airflow from HVAC registers or heat sources. Getting it moved to a better location may be necessary before you can judge if it's working properly.
Dirt and dust accumulations under the thermostat's cover can have an impact on its ability to read and control the temperature in your home. If you haven't cleaned it recently, take off the cover and use a soft brush to gently remove any buildup on the components. Then, put a dab of electrical contact cleaner on a cotton swab and remove any corrosion from the metal contacts.
Thermostats tend to become unreliable as they age. If you've tried all of the above suggestions and nothing worked, it's time to replace the unit. You can benefit from better thermostat temperature and energy consumption control and the latest convenience features when you install a new Wi-Fi or programmable model.
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Our goal is to help educate our customers in the South Bay Peninsula and Santa Cruz areas of California about energy and home comfort issues (specific to HVAC systems).