As the weather is cooling off, you may be concerned about how you’ll make the most of your heating and cooling. After all, HVAC bills frequently contribute a big piece of your monthly electric bill. To learn new ways to save, some homeowners look closer at their thermostat. Maybe there’s a setting they can use to improve efficiency?

Most thermostats come with a ‘Fan’ or ‘Fan On’ setting. But if the fan is on during a normal cycle, what will the fan setting offer for your HVAC system? This guide can help. We’ll share what exactly the fan setting is and when you can use it to reduce costs over the summer or winter.

What Is the Fan Setting on My Thermostat?

For the bulk of thermostats, the fan setting indicates that the system’s blower fan remains on. Some furnaces may continue to run at a low level in this setting, but for the most part heating or cooling isn’t being produced. The ‘Auto’ setting, conversely, will turn on the fan through a heating or cooling cycle and shut it off after the cycle is over.

There are pros and cons to trying the fan setting on your thermostat, and whether you do or don’t {will|can|should]] depend on your personal comfort preferences.

Advantages to trying the Fan/On setting:

  • You can keep the temperature in every room more consistent by permitting the fan to keep generating airflow.
  • Indoor air quality will be highest because constant airflow will keep passing airborne contaminants into 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 a component of the furnace, this means you might avoid needing furnace repair.

Downsides to switching to the Fan/On setting:

  • A constant fan could add to your energy bills by a small margin.
  • Constant airflow may clog your air filter up more quickly, increasing the frequency you should replace it.

{Choosing Between|Should My Thermostat Be on|Which Setting for My Thermostat? Fan or Auto in Summer/Winter

Through the summer, warm air may stick around in unfinished spaces such as 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, compelling the HVAC system to work more to maintain the desired temperature. In severe heat, this could lead to needing AC repair more quickly as wear and tear gets worse.

The reverse can happen in the winter. Cooler spaces such as a basement will hold onto cooler air, which may eventually flow into the rest of your home. Keeping the fan on will sometimes pull more cold air upward, increasing the amount of heating you need to stay warm.

If you’re still trying to figure out if you should try the fan/on setting, don’t forget that every home and family’s comfort needs are different. Leaving the HVAC system’s fan on might be best for you if:

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

Your home experiences hot and cold spots. All kinds of homes deal with persistent hot and cold spots that quickly shift to a temperature different from the rest of the house. The fan setting might help limit these changes by constantly refreshing each room’s supply of air.