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

Most thermostats come with a ‘Fan’ or ‘Fan On’ setting. But if the fan is on during a typical cycle, what can the fan setting offer for an HVAC system? This guide should help. We’ll review precisely what the fan setting is and whether you can use it to cut costs over the summer or winter.

What Is the Fan Setting on My Thermostat?

For the bulk of thermostats, the fan setting signifies that the system's blower fan remains on. A few furnaces may continue to generate heat at a low level in this setting, but in most cases heating or cooling isn’t being generated. The ‘Auto’ setting, on the other hand, will run the fan over a heating or cooling cycle and turn it off once the cycle is finished.

There are advantages and disadvantages to trying the fan setting on your thermostat, and what's ideal {will|can|should]] depend on your unique comfort preferences.

Advantages to utilizing the Fan/On setting:

  • You can keep the temperature in each room more uniform by enabling the fan to keep circulating air.
  • Indoor air quality should improve since continuous airflow will keep passing airborne particles through the air filter.
  • Fewer start-stop cycles for the system's fan helps lengthen its life span. As the air handler is usually part of the furnace, this means you can minimize the risk of needing furnace repair.

Drawbacks to utilizing the Fan/On setting:

  • A nonstop fan could raise your energy expenses somewhat.
  • Continuous airflow may clog your air filter soon, increasing the frequency you should replace it.

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

In the summer, warm air will sometimes stick around in unfinished spaces such as the attic or an attached garage. If you use the fan setting, your HVAC system might gradually move this warm air into the rest of your home, compelling the HVAC system to run longer to maintain the preferred temperature. In extreme heat, this can result in needing AC repair more often as wear and tear grows.

The reverse can happen over the winter. Cooler spaces like a basement will hold onto cooler air, which can eventually make its way into the rest of your home. Leaving the fan running 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 use the fan/on setting, remember that every home and family’s comfort needs will vary. 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 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 evolve to a temperature different from the rest of the house. The fan setting can help lessen these changes by steadily refreshing each room’s airflow.