Once the weather starts to cool off, you might be concerned about how you’ll make the most of your heating and cooling. After all, HVAC costs routinely contribute a large chunk of your monthly electric bill. To try and find ways to lower their HVAC bill, some homeowners look closer at their thermostat. Could there be a setting they can use to improve efficiency?

Most thermostats include both a ‘Fan’ or ‘Fan On’ setting. But if the fan is running during a regular cycle, what will the fan setting provide for your HVAC system? This guide will help. We’ll share precisely what the fan setting is and how you can use it to save money over the summer or winter.

What Is the Fan Setting on My Thermostat?

For most thermostats, the fan setting indicates that the air handler’s blower fan keeps running. A few furnaces will generate heat at a low level in this setting, but in general heating or cooling isn’t being produced. The ‘Auto’ setting, in contrast, will run the fan during a heating or cooling cycle and switch it off after the cycle is over.

There are pros and cons to switching on the fan setting on your thermostat, and whether you do or don’t {will|can|should]] depend on your personal comfort needs.

Advantages to trying the Fan/On setting:

  • You can keep the temperature in each room more uniform by enabling the fan to keep generating airflow.
  • Indoor air quality will be highest since constant airflow will keep moving 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 typically a component of the furnace, this means you can minimize the risk of needing furnace repair.

Downsides to utilizing the Fan/On setting:

  • A constant fan could increase your energy costs slightly.
  • Constant airflow can clog your air filter up more quickly, increasing the frequency you will want to replace it.

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

Through the summer, warm air will sometimes persist in unfinished spaces including the attic or an attached garage. If you use the fan setting, your HVAC system can gradually move this warm air into the rest of your home, pushing the HVAC system to work more to keep up with the preferred temperature. In serious heat, this could lead to needing AC repair more quickly as wear and tear grows.

The reverse can take place during 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 could pump more cold air upward, increasing the amount of heating you need to keep warm.

If you’re still trying to determine if you should try the fan/on setting, don’t forget that every home and family’s comfort needs are different. Leaving the HVAC system’s fan on may be best for you if:

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

Your home experiences hot and cold spots. Lots of homes wrestle with difficult 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 steadily refreshing each room’s airflow.