Once the weather is cooling off, you may be thinking about how you’ll prepare your heating and cooling. After all, HVAC costs routinely make up a large portion of your monthly electric bill. To learn new ways to lower their HVAC bill, some homeowners look closely at their thermostat. Could there be a setting they should use to boost efficiency?

The majority of thermostats have a ‘Fan’ or ‘Fan On’ setting. But if the fan is running during a normal cycle, what will the fan setting offer for your HVAC system? This guide can help. We’ll walk through what exactly the fan setting is and when 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 HVAC blower fan keeps running. A few furnaces will operate at a low level in this setting, but in general heating or cooling isn’t being generated. The ‘Auto’ setting, in contrast, will turn on the fan through a heating or cooling cycle and shut it off when the cycle is finished.

There are advantages and disadvantages 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 throughout your home more consistent by enabling the fan to keep circulating air.
  • Indoor air quality should improve as continuous airflow will keep forcing airborne particles into the air filter.
  • A smaller number of start-stop cycles for the HVAC fan helps extend its life span. As the air handler is usually 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 could raise your energy costs by a small margin.
  • Constant airflow could clog your air filter in a shorter amount of time, increasing the frequency you’ll need to replace it.

{Choosing Between|Should My Thermostat Be on|Which Setting for My Thermostat? Fan or Auto in Each Season

In the summer, warm air can stick around in unfinished spaces such as the attic or an attached garage. If you keep the fan running, your HVAC system might draw this warm air into the rest of your home, pushing the HVAC system to run longer to preserve the desired temperature. In serious heat, this could lead to needing AC repair more regularly as wear and tear increases.

The reverse can occur in the winter. Cooler spaces like a basement will hold onto cooler air, which will eventually drift into the rest of your home. Keeping the fan on may pump 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 use the fan/on setting, don’t forget that every home and family’s comfort needs are different. Leaving the HVAC system’s fan on might be best for you if:

Someone in your household suffers from allergies. Allergies and similar respiratory conditions can be stressful on the family. Leaving the fan on should help to improve indoor air quality, helping your family breathe easier.

Your home has hot and cold spots. Many homes deal with persistent hot and cold spots that quickly shift to a temperature different from the rest of the house. The fan setting might help lessen these changes by consistently refreshing each room’s ventilation.