When the weather starts to cool off, you might be wondering about how you’ll prepare your heating and cooling. After all, HVAC costs routinely add up to a large chunk of your monthly electric bill. To try and find ways to reduce costs, some people look closely at their thermostat. Is there a setting they can use to improve efficiency?

The bulk of thermostats have a ‘Fan’ or ‘Fan On’ setting. But if the fan is on during a typical cycle, what will the fan setting offer for an HVAC system? This guide can help. We’ll review just what the fan setting is and whether you can use it to reduce costs during the summer or winter.

My Thermostat Has a Fan Setting?

For most thermostats, the fan setting means that the HVAC blower fan keeps running. Some furnaces will generate heat at a low level with this setting, but for the most part heating or cooling isn’t being generated. The ‘Auto’ setting, in contrast, will turn on the fan over a heating or cooling cycle and turn it off when the cycle is complete.

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

Advantages to trying the Fan/On setting:

  • You can keep the temperature throughout your home more uniform by allowing the fan to keep circulating air.
  • Indoor air quality should improve because steady airflow will keep moving airborne contaminants through the air filter.
  • A smaller number of start-stop cycles for the blower fan helps extend its life span. Because the air handler is usually connected to the furnace, this means you could prevent the need for furnace repair.

Downsides to using the Fan/On setting:

  • A constant fan can increase your energy costs slightly.
  • Constant airflow may clog your air filter up more quickly, 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 Summer/Winter

During the summer, warm air can persist in unfinished spaces such as the attic or an attached garage. If you keep the fan running, your HVAC system may gradually move this warm air into the rest of your home, forcing the HVAC system to run longer to keep up with the preferred temperature. In serious heat, this may result in needing AC repair more quickly as wear and tear grows.

The opposite can happen during the winter. Cooler spaces like a basement will hold onto cooler air, which will eventually make its way into the rest of your home. Keeping the fan on may draw more cold air upward, increasing the amount of heating you need to keep warm.

If you’re still trying to determine if you should switch to the fan/on setting, keep in mind that every home and family’s comfort needs are different. Leaving the HVAC system’s fan on could work for you if:

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

Your home has hot and cold spots. All kinds of 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 steadily refreshing each room’s ventilation.