When the weather is cooling off, you are probably thinking about how you’ll prepare your heating and cooling. After all, HVAC costs frequently make up a big portion of your monthly electric bill. To try and find ways to save, some owners look closely at their thermostat. Maybe there’s a setting they should use to improve efficiency?

The bulk of thermostats come with a ‘Fan’ or ‘Fan On’ setting. But if the fan is running during a regular cycle, what can the fan setting provide for an HVAC system? This guide should help. We’ll share what exactly the fan setting is and when you can use it to save money in the summer or winter.

What Is the Fan Setting on My Thermostat?

For the bulk of thermostats, the fan setting indicates that the HVAC blower fan remains on. Certain furnaces may continue to run at a low level in this setting, but in most cases heating or cooling isn’t being produced. The ‘Auto’ setting, conversely, will run the fan over a heating or cooling cycle and shut it off once the cycle is finished.

There are advantages and disadvantages to trying the fan setting on your thermostat, and whether you do or don’t {will|can|should]] depend on your unique comfort requirements.

Advantages to trying the Fan/On setting:

  • You can keep the temperature in every room more uniform by permitting the fan to keep circulating air.
  • Indoor air quality can increase as constant airflow will keep passing airborne particles through the air filter.
  • A smaller number of start-stop cycles for the system's fan helps expand its life span. Because the air handler is typically part of the furnace, this means you can avoid needing furnace repair.

Downsides to using the Fan/On setting:

  • A nonstop fan can increase your energy bills by a small margin.
  • Nonstop airflow may clog your air filter in a shorter amount of time, increasing the frequency you should replace it.

Should My Thermostat Be on Fan or Auto in Summer/Winter

In the summer, warm air can stick around in unfinished spaces like the attic or an attached garage. If you use the fan setting, your HVAC system might draw this warm air into the rest of your home, forcing the HVAC system to work more to maintain the set temperature. In extreme heat, this can lead to needing AC repair more quickly as wear and tear grows.

The reverse can take place during the winter. Cooler spaces such as a basement will hold onto cooler air, which can eventually flow into the rest of your home. Leaving the fan setting on may pump more cold air upward, increasing the amount of heating you need to remain warm.

If you’re still trying to determine if you should use the fan/on setting, remember that every home and family’s comfort needs are different. Leaving the HVAC system’s fan on may work for you if:

Someone in your household deals with allergies. Allergies and other respiratory conditions can be stressful on the family. Leaving the fan on should help to enhance indoor air quality, helping your family breathe easier.

Your home has hot and cold spots. Lots of homes wrestle with stubborn hot and cold spots that quickly return to a temperature different from the rest of the house. The fan setting might help minimize these changes by constantly refreshing each room’s ventilation.