As the weather is cooling off, you may be concerned about how you’ll take full advantage of your heating and cooling. After all, HVAC costs routinely add up to a big piece 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 should use to improve efficiency?

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

What Is the Fan Setting on My Thermostat?

For most thermostats, the fan setting signifies that the system's blower fan keeps running. Some furnaces may continue to operate at a low level with this setting, but for the most part heating or cooling isn’t being made. The ‘Auto’ setting, on the other hand, will turn on the fan over a heating or cooling cycle and shut it off when the cycle is finished.

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

Advantages to switching to the Fan/On setting:

  • You can keep the temperature throughout your home more consistent by permitting the fan to keep running.
  • Indoor air quality will be highest since constant airflow will keep forcing airborne contaminants into the air filter.
  • A smaller amount of start-stop cycles for the HVAC fan helps extend its life span. Because the air handler is often part of the furnace, this means you can avoid needing furnace repair.

Drawbacks to switching to the Fan/On setting:

  • A constant fan could add to your energy costs by a small margin.
  • Constant airflow can clog your air filter up more quickly, increasing the frequency you should replace it.

{Choosing Between|Should My Thermostat Be on|Which Setting for My Thermostat? Fan or Auto in Summer/Winter

During the summer, warm air will sometimes stick around in unfinished spaces including the attic or an attached garage. If you keep the fan running, your HVAC system may pull this warm air into the rest of your home, pushing the HVAC system to run longer to preserve the desired temperature. In severe heat, this may lead to needing AC repair more quickly as wear and tear gets worse.

The reverse can take place during the winter. Cooler spaces like a basement will hold onto cooler air, which will eventually flow 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 remain warm.

If you’re still trying to decide if you should try the fan/on setting, keep in mind that every home and family’s comfort needs are different. Leaving the HVAC system’s fan on could be best for you if:

Someone in your household suffers from allergies. Allergies and similar respiratory conditions can be stressful on the family. Leaving the fan on is more likely to improve indoor air quality, helping your family breathe easier.

Your home deals with hot and cold spots. Lots of homes deal with persistent 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 constantly refreshing each room’s supply of air.