When the weather is cooling off, you are probably concerned about how you’ll take full advantage of your heating and cooling. After all, HVAC costs routinely make up a large chunk of your monthly electric bill. To try and find ways to reduce costs, some homeowners look closely at their thermostat. Could there be a setting they could use to improve efficiency?

Most thermostats include both a ‘Fan’ or ‘Fan On’ setting. But if the fan is going during a normal cycle, what does the fan setting provide for your HVAC system? This guide can help. We’ll walk through just what the fan setting is and when you can use it to cut costs during 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 air handler’s blower fan keeps running. A few furnaces will generate heat at a low level with this setting, but for the most part heating or cooling isn’t being generated. The ‘Auto’ setting, on the other hand, will turn on the fan over a heating or cooling cycle and shut it off after the cycle is over.

There are benefits and drawbacks to using the fan setting on your thermostat, and whether you do or don’t {will|can|should]] depend on your unique comfort preferences.

Advantages to switching to the Fan/On setting:

  • You can keep the temperature throughout your home more uniform by permitting the fan to keep generating airflow.
  • Indoor air quality should improve as constant airflow will keep forcing airborne pollutants through the air filter.
  • A smaller amount of start-stop cycles for the HVAC fan helps lengthen its life span. As the air handler is usually a component of the furnace, this means you can minimize the risk of needing furnace repair.

Downsides to switching to the Fan/On setting:

  • A constant fan can increase your energy costs by a small margin.
  • Nonstop airflow could 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 Each Season

During the summer, warm air will sometimes stick around in unfinished spaces such as the attic or an attached garage. If you leave the fan on, your HVAC system might gradually move this warm air into the rest of your home, forcing the HVAC system to work harder to maintain the desired temperature. In extreme heat, this can result in needing AC repair more regularly as wear and tear gets worse.

The opposite can occur in the winter. Cooler spaces such as a basement will hold onto cooler air, which will eventually flow into the rest of your home. Leaving the fan setting on could pull more cold air upward, increasing the amount of heating you need to stay 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 are not the same. Leaving the HVAC system’s fan on could work for you if:

Someone in your household deals with allergies. Allergies and other respiratory conditions can be tough 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. All kinds of homes deal with difficult hot and cold spots that quickly return to a temperature different from the rest of the house. The fan setting can help minimize these changes by constantly refreshing each room’s ventilation.