As the weather is cooling off, you might be wondering about how you’ll prepare your heating and cooling. After all, HVAC bills can add up to a big portion of your monthly electric bill. To learn new ways to save, some people look closer at their thermostat. Is there a setting they should use to boost efficiency?

Most thermostats come with a ‘Fan’ or ‘Fan On’ setting. But if the fan is running during a typical cycle, what does the fan setting provide for your HVAC system? This guide will help. We’ll walk through just what the fan setting is and how you can use it to reduce costs over the summer or winter.

What Is the Fan Setting on My Thermostat?

For most thermostats, the fan setting signifies that the system's blower fan stays on. A few furnaces can run at a low level in this setting, but in general heating or cooling isn’t being produced. The ‘Auto’ setting, conversely, will start the fan during a heating or cooling cycle and shut it off once the cycle is over.

There are pros and cons to using the fan setting on your thermostat, and the ideal option {will|can|should]] depend on your distinct comfort preferences.

Advantages to trying the Fan/On setting:

  • You can keep the temperature throughout your home more uniform by allowing the fan to keep circulating air.
  • Indoor air quality can increase because constant airflow will keep forcing airborne pollutants into the air filter.
  • Fewer start-stop cycles for the blower fan helps expand its life span. Because the air handler is usually part of the furnace, this means you can prevent the need for furnace repair.

Drawbacks to switching to the Fan/On setting:

  • A nonstop fan will likely raise your energy expenses somewhat.
  • Continuous airflow could clog your air filter soon, increasing the frequency you should replace it.

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

Through the summer, warm air will sometimes stick around in unfinished spaces such as the attic or an attached garage. If you use the fan setting, your HVAC system can draw 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 could result in needing AC repair more often as wear and tear gets worse.

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

If you’re still trying to decide if you should use the fan/on setting, keep in mind that every home and family’s comfort needs are different. 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 tough on the family. Leaving the fan on should help to increase indoor air quality, helping your family breathe easier.

Your home has hot and cold spots. Lots of homes deal with difficult hot and cold spots that quickly shift 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.