Once the weather begins to cool off, you are probably concerned about how you’ll take full advantage of your heating and cooling. After all, HVAC expenses frequently make up a large chunk of your monthly electric bill. To figure out new ways to save, some owners look closer at their thermostat. Maybe there’s a setting they could use to improve efficiency?

Most thermostats include both a ‘Fan’ or ‘Fan On’ setting. But if the fan is on during a typical cycle, what will the fan setting offer for an HVAC system? This guide can help. We’ll walk through precisely what the fan setting is and whether 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 means that the HVAC blower fan remains on. Some furnaces will operate at a low level in this setting, but for the most part heating or cooling isn’t being produced. The ‘Auto’ setting, in contrast, will run the fan over a heating or cooling cycle and turn it off once the cycle is over.

There are pros and cons to switching on the fan setting on your thermostat, and whether you do or don’t {will|can|should]] depend on your unique comfort needs.

Advantages to utilizing the Fan/On setting:

  • You can keep the temperature in every room more consistent by enabling the fan to keep running.
  • Indoor air quality should improve as constant airflow will keep forcing airborne pollutants into the air filter.
  • A smaller number of start-stop cycles for the system's fan helps extend its life span. As the air handler is often a component of the furnace, this means you can minimize the risk of needing furnace repair.

Disadvantages to utilizing the Fan/On setting:

  • A nonstop fan could add to your energy expenses somewhat.
  • Constant airflow may clog your air filter soon, 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

In the summer, warm air can persist in unfinished spaces including the attic or an attached garage. If you leave the fan on, your HVAC system may pull this warm air into the rest of your home, compelling the HVAC system to run longer to preserve the set temperature. In severe heat, this may lead to needing AC repair more often as wear and tear gets worse.

The opposite can happen during the winter. Cooler spaces like a basement will hold onto cooler air, which may eventually flow into the rest of your home. Keeping the fan on could pull more cold air upward, increasing the amount of heating you need to remain warm.

If you’re still trying to decide if you should switch to the fan/on setting, remember that every home and family’s comfort needs will vary. Leaving the HVAC system’s fan on may be best for you if:

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

Your home has hot and cold spots. All kinds 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 might help minimize these changes by steadily refreshing each room’s airflow.