As the weather begins to cool off, you may be wondering about how you’ll take full advantage of your heating and cooling. After all, HVAC expenses routinely contribute a significant chunk of your monthly electric bill. To figure out new ways to save, some homeowners look closer at their thermostat. Maybe there’s a setting they can use to boost efficiency?

Most thermostats include both a ‘Fan’ or ‘Fan On’ setting. But if the fan is on during a normal cycle, what does the fan setting provide for an HVAC system? This guide can help. We’ll walk through precisely what the fan setting is and how you can use it to save money during the summer or winter.

My Thermostat Has a Fan Setting?

For most thermostats, the fan setting signifies that the system’s blower fan remains on. A few furnaces will operate at a low level in this setting, but for the most part heating or cooling isn’t being generated. The ‘Auto’ setting, in contrast, will run the fan over a heating or cooling cycle and turn it off when the cycle is over.

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 using the Fan/On setting:

  • You can keep the temperature in every room more consistent by allowing the fan to keep generating airflow.
  • Indoor air quality will be highest because steady airflow will keep moving airborne pollutants through the air filter.
  • A smaller number of start-stop cycles for the system’s fan helps expand its life span. Since the air handler is typically a component of the furnace, this means you can minimize the risk of needing furnace repair.

Disadvantages to switching to the Fan/On setting:

  • A nonstop fan can add to your energy costs somewhat.
  • Nonstop airflow can 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 can stick around in unfinished spaces such as the attic or an attached garage. If you use the fan setting, your HVAC system might pull this warm air into the rest of your home, compelling the HVAC system to work more to maintain the desired temperature. In extreme heat, this may lead to needing AC repair more often as wear and tear gets worse.

The reverse 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 keep warm.

If you’re still trying to determine if you should switch to the fan/on setting, keep in mind that every home and family’s comfort needs will vary. 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 is more likely to improve indoor air quality, helping your family breathe easier.

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