Once the weather is cooling off, you may be wondering about how you’ll take full advantage of your heating and cooling. After all, HVAC costs frequently make up a significant piece of your monthly electric bill. To figure out new ways to reduce costs, some owners look closely at their thermostat. Maybe there’s a setting they should use to improve efficiency?

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

Should I Use My Thermostat’s Fan Setting?

For the bulk of thermostats, the fan setting indicates that the HVAC blower fan remains on. Some furnaces will run at a low level in this setting, but for the most part heating or cooling isn’t being produced. The ‘Auto’ setting, in contrast, will run the fan over a heating or cooling cycle and shut it off when 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 unique comfort preferences.

Advantages to using the Fan/On setting:

  • You can keep the temperature in each room more balanced by allowing the fan to keep generating airflow.
  • Indoor air quality should improve as steady airflow will keep forcing airborne particles through the air filter.
  • Fewer start-stop cycles for the system’s fan helps expand its life span. As the air handler is typically connected to the furnace, this means you can minimize the risk of needing furnace repair.

Disadvantages to using the Fan/On setting:

  • A constant fan will likely increase your energy costs somewhat.
  • Constant airflow can clog your air filter soon, 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 will sometimes stick around in unfinished spaces including the attic or an attached garage. If you keep the fan running, 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 desired temperature. In severe heat, this could lead to needing AC repair more regularly as wear and tear gets worse.

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

If you’re still trying to figure out if you should switch to the fan/on setting, don’t forget that every home and family’s comfort needs are different. Leaving the HVAC system’s fan on may 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 improve indoor air quality, helping your family breathe easier.

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