When the weather starts to cool off, you are probably thinking about how you’ll prepare your heating and cooling. After all, HVAC expenses frequently make up a significant portion of your monthly electric bill. To figure out new ways to lower their HVAC bill, some people look closer at their thermostat. Is there a setting they can use to boost efficiency?

Most thermostats come with a ‘Fan’ or ‘Fan On’ setting. But if the fan is going during a typical cycle, what can the fan setting offer for the HVAC system? This guide can help. We’ll share what exactly the fan setting is and when you can use it to cut costs during the summer or winter.

Should I Use My Thermostat's Fan Setting?

For most thermostats, the fan setting signifies that the air handler’s blower fan keeps running. Some furnaces will generate heat at a low level in this setting, but for the most part 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 after 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 distinct comfort preferences.

Advantages to using the Fan/On setting:

  • You can keep the temperature in each room more uniform by allowing the fan to keep circulating air.
  • Indoor air quality can increase because continuous airflow will keep passing airborne contaminants into the air filter.
  • A smaller number of start-stop cycles for the system's fan helps expand its life span. As the air handler is usually a component of the furnace, this means you could minimize the risk of needing furnace repair.

Disadvantages to using the Fan/On setting:

  • A nonstop fan could add to your energy bills slightly.
  • Nonstop airflow could clog your air filter up more quickly, increasing the frequency you’ll need to 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 will sometimes stick around in unfinished spaces like the attic or an attached garage. If you leave the fan on, your HVAC system can pull this warm air into the rest of your home, compelling the HVAC system to work more to keep up with the desired temperature. In serious heat, this could result in needing AC repair more regularly as wear and tear grows.

The reverse can take place in the winter. Cooler spaces like a basement will hold onto cooler air, which may eventually drift into the rest of your home. Leaving the fan running will sometimes pump 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 might be best for you if:

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

Your home has hot and cold spots. Many 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 limit these changes by consistently refreshing each room’s airflow.