When the weather begins to cool off, you are probably thinking about how you’ll prepare your heating and cooling. After all, HVAC costs can contribute a big portion of your monthly electric bill. To figure out new ways to lower their HVAC bill, some homeowners look closer at their thermostat. Maybe there’s a setting they should use to boost efficiency?

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

What Is the Fan Setting on My Thermostat?

For the majority of thermostats, the fan setting means that the system's blower fan keeps running. A few furnaces may continue to run at a low level with this setting, but in most cases heating or cooling isn’t being generated. The ‘Auto’ setting, conversely, will run the fan during a heating or cooling cycle and shut it off once the cycle is finished.

There are benefits and drawbacks to using the fan setting on your thermostat, and what's ideal {will|can|should]] depend on your personal comfort requirements.

Advantages to switching to the Fan/On setting:

  • You can keep the temperature in every room more uniform by enabling the fan to keep circulating air.
  • Indoor air quality can increase as continuous airflow will keep forcing airborne pollutants into the air filter.
  • A smaller amount of start-stop cycles for the HVAC fan helps lengthen its life span. Because the air handler is typically part of the furnace, this means you can minimize the risk of needing furnace repair.

Drawbacks to using the Fan/On setting:

  • A constant fan will likely increase your energy bills slightly.
  • Nonstop airflow may clog your air filter up more quickly, increasing the frequency you will want to replace it.

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

In the summer, warm air will sometimes persist in unfinished spaces such as the attic or an attached garage. If you leave the fan on, your HVAC system can draw this warm air into the rest of your home, pushing the HVAC system to run longer to maintain the set temperature. In serious heat, this can lead to needing AC repair more regularly as wear and tear gets worse.

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

If you’re still trying to determine 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 might be ideal for you if:

Someone in your household suffers from 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 deals with hot and cold spots. Lots of homes deal with stubborn hot and cold spots that quickly return to a temperature different from the rest of the house. The fan setting might help minimize these changes by constantly refreshing each room’s airflow.