As the weather is cooling off, you might be concerned about how you’ll prepare your heating and cooling. After all, HVAC costs frequently contribute a large chunk of your monthly electric bill. To figure out new ways to reduce costs, some people look closer at their thermostat. Maybe there’s a setting they should use to boost efficiency?

The bulk of thermostats have a ‘Fan’ or ‘Fan On’ setting. But if the fan is on during a typical cycle, what does the fan setting provide for an HVAC system? This guide can help. We’ll walk through what exactly the fan setting is and whether you can use it to cut costs during the summer or winter.

My Thermostat Has a Fan Setting?

For most thermostats, the fan setting indicates that the air handler’s blower fan stays on. Certain furnaces may continue to generate heat at a low level with this setting, but in general heating or cooling isn’t being generated. The ‘Auto’ setting, in contrast, will turn on the fan over a heating or cooling cycle and turn it off when the cycle is finished.

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

Advantages to switching to the Fan/On setting:

  • You can keep the temperature in each room more uniform by allowing the fan to keep generating airflow.
  • Indoor air quality can increase since continuous airflow will keep forcing airborne pollutants into the air filter.
  • A smaller amount of start-stop cycles for the blower fan helps lengthen its life span. As the air handler is often connected to the furnace, this means you can avoid needing furnace repair.

Drawbacks to using the Fan/On setting:

  • A nonstop fan can increase your energy costs slightly.
  • Constant airflow may clog your air filter in a shorter amount of time, 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

Through the summer, warm air may persist in unfinished spaces including the attic or an attached garage. If you keep the fan running, your HVAC system might draw 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 increases.

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

If you’re still trying to determine if you should switch to 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 be best for you if:

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

Your home experiences hot and cold spots. Lots of homes deal with stubborn hot and cold spots that quickly return to a temperature different from the rest of the house. The fan setting might help minimize these changes by steadily refreshing each room’s ventilation.