When the weather begins to cool off, you might be concerned about how you’ll take full advantage of your heating and cooling. After all, HVAC costs routinely make up a significant chunk of your monthly electric bill. To figure out new ways to save, some owners take a closer look at their thermostat. Maybe there’s a setting they can use to increase efficiency?

Most thermostats come with a ‘Fan’ or ‘Fan On’ setting. But if the fan is on during a regular 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 cut costs during the summer or winter.

My Thermostat Has a Fan Setting?

For most thermostats, the fan setting signifies that the HVAC blower fan keeps running. A few furnaces may continue to operate at a low level with 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 once the cycle is finished.

There are advantages and disadvantages to trying the fan setting on your thermostat, and whether you do or don’t {will|can|should]] depend on your personal comfort preferences.

Advantages to switching to the Fan/On setting:

  • You can keep the temperature in each room more consistent by allowing the fan to keep running.
  • Indoor air quality should improve because constant airflow will keep passing airborne pollutants into the air filter.
  • A smaller number of start-stop cycles for the system’s fan helps extend its life span. Since the air handler is often part of the furnace, this means you can prevent the need for furnace repair.

Downsides to utilizing the Fan/On setting:

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

{Choosing Between|Should My Thermostat Be on|Which Setting for My Thermostat? Fan or Auto in Summer/Winter

Through the summer, warm air may linger in unfinished spaces including the attic or an attached garage. If you keep the fan running, your HVAC system may draw this warm air into the rest of your home, pushing the HVAC system to run longer to preserve the set temperature. In severe heat, this may lead to needing AC repair more regularly as wear and tear increases.

The opposite can occur in the winter. Cooler spaces such as a basement will hold onto cooler air, which will eventually flow into the rest of your home. Keeping the fan on may 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 switch to the fan/on setting, remember that every home and family’s comfort needs are not the same. Leaving the HVAC system’s fan on may work for you if:

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

Your home experiences hot and cold spots. All kinds of homes deal with difficult hot and cold spots that quickly return to a temperature different from the rest of the house. The fan setting should help minimize these changes by constantly refreshing each room’s airflow.