When the weather is cooling off, you might be thinking about how you’ll take full advantage of your heating and cooling. After all, HVAC costs routinely contribute a big chunk of your monthly electric bill. To try and find ways to save, some homeowners look closer at their thermostat. Is there a setting they should use to boost efficiency?

The majority of thermostats have a ‘Fan’ or ‘Fan On’ setting. But if the fan is running during a regular cycle, what can the fan setting offer for the HVAC system? This guide will help. We’ll walk through just what the fan setting is and when you can use it to cut costs in the summer or winter.

My Thermostat Has a Fan Setting?

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

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 distinct comfort preferences.

Advantages to utilizing the Fan/On setting:

  • You can keep the temperature throughout your home more uniform by allowing the fan to keep running.
  • Indoor air quality will be highest since steady airflow will keep moving airborne pollutants into the air filter.
  • A smaller number of start-stop cycles for the system’s fan helps extend its life span. Because the air handler is usually connected to the furnace, this means you could avoid needing furnace repair.

Downsides to using the Fan/On setting:

  • A constant fan can raise your energy expenses slightly.
  • Continuous airflow can clog your air filter up more quickly, increasing the frequency you will want 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 including 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, compelling the HVAC system to work harder to preserve the desired temperature. In extreme heat, this may result in needing AC repair more regularly as wear and tear gets worse.

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

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

Someone in your household has allergies. Allergies and similar respiratory conditions can be hard on the family. Leaving the fan on should help to enhance 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 shift to a temperature different from the rest of the house. The fan setting should help limit these changes by steadily refreshing each room’s ventilation.