Once the weather begins to cool off, you might be wondering about how you’ll take full advantage of your heating and cooling. After all, HVAC bills routinely make up a large chunk of your monthly electric bill. To figure out new ways to save, some owners take a closer look at their thermostat. Is there a setting they should use to boost efficiency?

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

What Is the Fan Setting on My Thermostat?

For the bulk of thermostats, the fan setting indicates that the HVAC blower fan stays on. Some furnaces may continue to generate heat at a low level with this setting, but in most cases 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 after the cycle is finished.

There are advantages and disadvantages to switching on the fan setting on your thermostat, and the ideal option {will|can|should]] depend on your distinct comfort needs.

Advantages to switching to the Fan/On setting:

  • You can keep the temperature in every room more consistent by allowing the fan to keep generating airflow.
  • Indoor air quality can increase as constant airflow will keep passing airborne pollutants into the air filter.
  • Fewer start-stop cycles for the system's fan helps expand its life span. Since the air handler is often connected to the furnace, this means you can prevent the need for furnace repair.

Disadvantages to using the Fan/On setting:

  • A constant fan can add to your energy bills somewhat.
  • Constant airflow may clog your air filter in a shorter amount of time, increasing the frequency you will want to replace it.

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

In the summer, warm air can stick around in unfinished spaces like 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, forcing the HVAC system to work harder to keep up with the preferred temperature. In severe heat, this can lead to needing AC repair more often as wear and tear gets worse.

The reverse can take place over the winter. Cooler spaces such as a basement will hold onto cooler air, which will eventually drift into the rest of your home. Leaving the fan setting on could draw more cold air upward, increasing the amount of heating you need to stay 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 not the same. Leaving the HVAC system’s fan on might be ideal for you if:

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

Your home deals with hot and cold spots. Lots of homes wrestle with persistent hot and cold spots that quickly shift to a temperature different from the rest of the house. The fan setting should help limit these changes by consistently refreshing each room’s airflow.