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

The majority of thermostats include both a ‘Fan’ or ‘Fan On’ setting. But if the fan is on during a regular cycle, what will the fan setting provide for your HVAC system? This guide can help. We’ll share precisely what the fan setting is and how you can use it to cut costs over the summer or winter.

What Is the Fan Setting on My Thermostat?

For the bulk of thermostats, the fan setting indicates that the system's blower fan keeps running. A few furnaces can operate at a low level in this setting, but in general heating or cooling isn’t being produced. The ‘Auto’ setting, conversely, will run the fan over a heating or cooling cycle and shut it off when the cycle is over.

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

Advantages to using the Fan/On setting:

  • You can keep the temperature in each room more uniform by permitting the fan to keep running.
  • Indoor air quality should improve because continuous airflow will keep moving airborne pollutants into the air filter.
  • A smaller number of start-stop cycles for the HVAC fan helps lengthen its life span. As the air handler is typically a component of the furnace, this means you could minimize the risk of needing furnace repair.

Disadvantages to using the Fan/On setting:

  • A nonstop fan could increase your energy bills slightly.
  • Constant airflow could clog your air filter soon, increasing the frequency you’ll need to replace it.

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

Through the summer, warm air may stick around in unfinished spaces like 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, compelling the HVAC system to work harder to maintain the desired temperature. In extreme heat, this could result in needing AC repair more often as wear and tear grows.

The reverse can occur during the winter. Cooler spaces like a basement will hold onto cooler air, which can eventually flow into the rest of your home. Leaving the fan running will sometimes 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 try the fan/on setting, remember that every home and family’s comfort needs are not the same. Leaving the HVAC system’s fan on might work for you if:

Someone in your household has allergies. Allergies and other respiratory conditions can be hard on the family. Leaving the fan on is more likely to increase indoor air quality, helping your family breathe easier.

Your home experiences hot and cold spots. Lots of homes deal with persistent hot and cold spots that quickly return to a temperature different from the rest of the house. The fan setting might help lessen these changes by constantly refreshing each room’s supply of air.