Is your thermostat showing the wrong temperature? Thermostats control the heating, ventilation and cooling (HVAC) systems with which they are used. Your air conditioning system and furnace – or heat pump – will turn on and turn off depending on the temperature displayed by the thermostat.
Thermostats, of course, display the ambient room temperature. Your furnace will turn on if the ambient room temperature drops below the temperature for which you set the thermostat. And your air conditioning system will turn on if the ambient room temperature rises above the temperature for which you set the thermostat. Thermostats may not show the correct ambient room temperature. Rather, they may show the wrong temperature in the following circumstances.
Poorly Placed Thermostat
The placement of your thermostat can affect its ability to sense, as well as show, the correct ambient room temperature. All thermostats rely on a sensor to measure the ambient room temperature. With the exception of smart thermostats, most models feature a built-in sensor. They will use this sensor to constantly measure the surrounding temperature.
Different areas of your home, however, may have different ambient temperatures. Attics and crawlspaces may be cooler during the winter and warmer during the summer than the rest of your home. Walls near heat-generating appliances like ovens and fireplaces may also be warmer than the rest of your home. If your thermostat is placed in one of these areas, it may show a temperature that’s different than your home’s true ambient temperature.
Even if your thermostat is placed in the right area, a faulty sensor may result in it showing the wrong temperature. Temperature sensors can fail. Most thermostats use an electro-mechanical sensor. These electro-mechanical sensors can rust and degrade over time. And eventually, they may fail.
If your thermostat has a faulty temperature sensor, it may show the wrong temperature. You may notice a temperature that’s higher or lower than your home’s true ambient temperature. Alternatively, your thermostat may not show any temperature if the sensor has failed.
Depending on the type of thermostat you have, it may show the wrong temperature if it’s not level. Old thermostats contain a small amount of mercury. If they aren’t level, they won’t be able to sense the correct temperature. This isn’t a concern for new thermostats. New thermostats don’t use mercury, so an unlevel placement won’t affect their ability to sense the correct temperature.