Once the weather is cooling off, you are probably concerned about how you’ll prepare your heating and cooling. After all, HVAC bills routinely add up to a large chunk of your monthly electric bill. To figure out new ways to reduce costs, some people look closely at their thermostat. Maybe there’s a setting they can use to improve efficiency?

The bulk of thermostats come with a ‘Fan’ or ‘Fan On’ setting. But if the fan is going during a normal cycle, what does the fan setting offer for your HVAC system? This guide should help. We’ll walk through what exactly the fan setting is and how you can use it to cut costs in the summer or winter.

What Is the Fan Setting on My Thermostat?

For most thermostats, the fan setting means that the air handler’s blower fan remains on. A few furnaces may continue to operate at a low level with this setting, but for the most part heating or cooling isn’t being generated. The ‘Auto’ setting, conversely, will start the fan through a heating or cooling cycle and shut it off when the cycle is finished.

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

Advantages to utilizing the Fan/On setting:

  • You can keep the temperature in every room more balanced by enabling the fan to keep running.
  • Indoor air quality should improve since constant airflow will keep passing airborne contaminants through the air filter.
  • Fewer start-stop cycles for the system's fan helps lengthen its life span. As the air handler is usually a component of the furnace, this means you can minimize the risk of needing furnace repair.

Downsides to using the Fan/On setting:

  • A continuous fan will likely raise your energy bills somewhat.
  • Constant airflow may clog your air filter soon, increasing the frequency you’ll need to 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 can linger in unfinished spaces such as the attic or an attached garage. If you leave the fan on, your HVAC system might gradually move this warm air into the rest of your home, forcing the HVAC system to run longer to keep up with the preferred temperature. In serious heat, this can result in needing AC repair more quickly as wear and tear gets worse.

The opposite can take place over the winter. Cooler spaces like a basement will hold onto cooler air, which will eventually drift into the rest of your home. Leaving the fan setting on will sometimes draw more cold air upward, increasing the amount of heating you need to remain warm.

If you’re still trying to determine if you should switch to the fan/on setting, don’t forget that every home and family’s comfort needs are not the same. Leaving the HVAC system’s fan on may be ideal for you if:

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

Your home deals with hot and cold spots. Lots of homes deal with persistent hot and cold spots that quickly evolve to a temperature different from the rest of the house. The fan setting should help limit these changes by steadily refreshing each room’s supply of air.