Once the weather begins to cool off, you might be thinking about how you’ll make the most of your heating and cooling. After all, HVAC bills can make up a significant chunk of your monthly electric bill. To try and find ways to reduce costs, some owners take a closer look at their thermostat. Maybe there’s a setting they should use to increase efficiency?

Most thermostats have a ‘Fan’ or ‘Fan On’ setting. But if the fan is going during a regular cycle, what will the fan setting provide for an HVAC system? This guide can help. We’ll walk through just what the fan setting is and whether you can use it to reduce costs during the summer or winter.

Should I Use My Thermostat's Fan Setting?

For most thermostats, the fan setting means that the system's blower fan stays on. Certain furnaces may continue to operate at a low level in this setting, but in general heating or cooling isn’t being made. The ‘Auto’ setting, in contrast, will run the fan through a heating or cooling cycle and switch it off after the cycle is over.

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

Advantages to using the Fan/On setting:

  • You can keep the temperature in every room more uniform by enabling the fan to keep generating airflow.
  • Indoor air quality should improve because steady airflow will keep forcing airborne pollutants into the air filter.
  • Fewer start-stop cycles for the blower fan helps extend its life span. Since the air handler is typically connected to the furnace, this means you might prevent the need for furnace repair.

Downsides to utilizing the Fan/On setting:

  • A constant fan will likely raise your energy bills 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 Each Season

In the summer, warm air will sometimes persist 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, compelling the HVAC system to work more to preserve the desired temperature. In serious heat, this may result in needing AC repair more quickly as wear and tear grows.

The opposite can take place over 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 setting on may pump more cold air upward, increasing the amount of heating you need to keep warm.

If you’re still trying to figure out if you should try the fan/on setting, keep in mind that every home and family’s comfort needs will vary. Leaving the HVAC system’s fan on may work for you if:

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

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