When the weather starts to cool off, you are probably thinking about how you’ll prepare your heating and cooling. After all, HVAC expenses can contribute a big portion 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 could use to increase efficiency?

Most thermostats come with a ‘Fan’ or ‘Fan On’ setting. But if the fan is going during a normal cycle, what will the fan setting provide for the HVAC system? This guide should help. We’ll share just what the fan setting is and whether you can use it to save money in the summer or winter.

What Is the Fan Setting on My Thermostat?

For the bulk of thermostats, the fan setting means that the system's blower fan remains on. Some furnaces may continue to run at a low level with this setting, but in general heating or cooling isn’t being produced. The ‘Auto’ setting, on the other hand, will run the fan over a heating or cooling cycle and shut it off once the cycle is complete.

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

Advantages to using the Fan/On setting:

  • You can keep the temperature in every room more uniform by allowing the fan to keep circulating air.
  • Indoor air quality should improve since constant airflow will keep forcing airborne contaminants through the air filter.
  • A smaller number of start-stop cycles for the blower fan helps expand its life span. Since the air handler is typically connected to the furnace, this means you can minimize the risk of needing furnace repair.

Drawbacks to utilizing the Fan/On setting:

  • A nonstop fan can increase your energy expenses by a small margin.
  • Continuous airflow can clog your air filter up more quickly, increasing the frequency you should replace it.

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

In the summer, warm air may linger in unfinished spaces such as the attic or an attached garage. If you keep the fan running, your HVAC system can draw this warm air into the rest of your home, forcing the HVAC system to work more to preserve the desired temperature. In severe heat, this may lead to needing AC repair more often as wear and tear grows.

The opposite can take place in the winter. Cooler spaces like a basement will hold onto cooler air, which may eventually drift into the rest of your home. Keeping the fan on will sometimes draw 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 try the fan/on setting, keep in mind that every home and family’s comfort needs are not the same. Leaving the HVAC system’s fan on might be best for you if:

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

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