When the weather is cooling off, you may be thinking about how you’ll take full advantage of your heating and cooling. After all, HVAC costs frequently contribute a large piece of your monthly electric bill. To figure out new ways to lower their HVAC bill, some people look closer at their thermostat. Maybe there’s a setting they can use to improve efficiency?

The bulk of 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 an HVAC system? This guide should help. We’ll review what exactly the fan setting is and whether you can use it to save money over 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 system's blower fan keeps running. Some furnaces can run at a low level in this setting, but for the most part heating or cooling isn’t being generated. The ‘Auto’ setting, conversely, will start the fan over a heating or cooling cycle and shut it off once the cycle is complete.

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

Advantages to using the Fan/On setting:

  • You can keep the temperature throughout your home more uniform by enabling the fan to keep running.
  • Indoor air quality can increase since continuous airflow will keep moving airborne contaminants into the air filter.
  • A smaller number of start-stop cycles for the blower fan helps lengthen its life span. As the air handler is often a component of the furnace, this means you might avoid needing furnace repair.

Drawbacks to switching to the Fan/On setting:

  • A continuous fan can raise your energy costs somewhat.
  • Continuous airflow may clog your air filter soon, 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

Through the summer, warm air may stick around in unfinished spaces including the attic or an attached garage. If you use the fan setting, your HVAC system may gradually move this warm air into the rest of your home, pushing the HVAC system to run longer to keep up with the preferred temperature. In severe heat, this can lead to needing AC repair more regularly as wear and tear grows.

The reverse can happen over the winter. Cooler spaces such as a basement will hold onto cooler air, which can eventually drift into the rest of your home. Keeping the fan on will sometimes pull more cold air upward, increasing the amount of heating you need to stay warm.

If you’re still trying to figure out if you should try the fan/on setting, keep in mind 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 has 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 experiences hot and cold spots. Lots of homes wrestle with difficult hot and cold spots that quickly shift to a temperature different from the rest of the house. The fan setting can help minimize these changes by consistently refreshing each room’s ventilation.