As the weather starts to cool off, you might be thinking about how you’ll make the most of your heating and cooling. After all, HVAC expenses routinely make up a big portion of your monthly electric bill. To figure out new ways to save, some owners take a closer look at their thermostat. Maybe there’s a setting they can use to improve efficiency?

The majority of thermostats come with a ‘Fan’ or ‘Fan On’ setting. But if the fan is on during a normal cycle, what does the fan setting provide for your HVAC system? This guide will help. We’ll review what exactly the fan setting is and how you can use it to save money over the summer or winter.

What Is the Fan Setting on My Thermostat?

For the bulk of thermostats, the fan setting indicates that the system's blower fan stays on. A few furnaces can operate at a low level in this setting, but in most cases heating or cooling isn’t being produced. The ‘Auto’ setting, in contrast, will start the fan during a heating or cooling cycle and shut it off after the cycle is finished.

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

Advantages to using the Fan/On setting:

  • You can keep the temperature in each room more balanced by enabling the fan to keep circulating air.
  • Indoor air quality will be highest since steady airflow will keep forcing airborne pollutants into the air filter.
  • A smaller number of start-stop cycles for the HVAC fan helps extend its life span. Since the air handler is typically connected to the furnace, this means you could minimize the risk of needing furnace repair.

Drawbacks to utilizing the Fan/On setting:

  • A constant fan can add to your energy bills by a small margin.
  • Constant airflow can clog your air filter in a shorter amount of time, increasing the frequency you will want to replace it.

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

Through the summer, warm air may stick around in unfinished spaces like the attic or an attached garage. If you keep the fan running, your HVAC system can gradually move this warm air into the rest of your home, compelling the HVAC system to run longer to preserve the desired temperature. In severe heat, this may result in needing AC repair more quickly as wear and tear gets worse.

The opposite can occur over the winter. Cooler spaces such as a basement will hold onto cooler air, which will eventually make its way into the rest of your home. Leaving the fan running may pull more cold air upward, increasing the amount of heating you need to keep warm.

If you’re still trying to decide if you should use the fan/on setting, keep in mind that every home and family’s comfort needs are not the same. Leaving the HVAC system’s fan on may be ideal for you if:

Someone in your household has allergies. Allergies and other respiratory conditions can be hard on the family. Leaving the fan on is more likely to enhance indoor air quality, helping your family breathe easier.

Your home has hot and cold spots. All kinds of homes wrestle with difficult hot and cold spots that quickly return to a temperature different from the rest of the house. The fan setting should help minimize these changes by steadily refreshing each room’s supply of air.