When the weather starts to cool off, you may be thinking about how you’ll make the most of your heating and cooling. After all, HVAC bills routinely contribute a big piece of your monthly electric bill. To figure out new ways to save, some people look closer at their thermostat. Maybe there’s a setting they should use to boost efficiency?

The bulk of thermostats have a ‘Fan’ or ‘Fan On’ setting. But if the fan is running during a regular cycle, what does the fan setting offer for an HVAC system? This guide can help. We’ll review what exactly the fan setting is and whether you can use it to save money during the summer or winter.

How Do I Access the Fan Setting on My Thermostat?

For the bulk of thermostats, the fan setting indicates that the HVAC blower fan keeps running. Some furnaces may continue to generate heat at a low level with this setting, but for the most part heating or cooling isn’t being made. The ‘Auto’ setting, in contrast, will run the fan during a heating or cooling cycle and turn it off when the cycle is complete.

There are pros and cons to trying the fan setting on your thermostat, and whether you do or don’t {will|can|should]] depend on your distinct 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 as constant airflow will keep moving airborne particles through the air filter.
  • A smaller amount of start-stop cycles for the blower fan helps extend its life span. Because the air handler is often a component of the furnace, this means you can prevent the need for furnace repair.

Drawbacks to using the Fan/On setting:

  • A constant fan will likely increase your energy bills slightly.
  • Continuous airflow could clog your air filter soon, increasing the frequency you will want to 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 like the attic or an attached garage. If you keep the fan running, your HVAC system might gradually move this warm air into the rest of your home, pushing the HVAC system to work more to preserve the desired temperature. In serious heat, this could result in needing AC repair more often as wear and tear grows.

The opposite can occur during the winter. Cooler spaces such as a basement will hold onto cooler air, which may eventually flow into the rest of your home. Leaving the fan running will sometimes pump more cold air upward, increasing the amount of heating you need to stay warm.

If you’re still trying to decide if you should try the fan/on setting, don’t forget 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 suffers from allergies. Allergies and similar respiratory conditions can be hard on the family. Leaving the fan on can help to improve indoor air quality, helping your family breathe easier.

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