Once the weather starts to cool off, you may be concerned about how you’ll prepare your heating and cooling. After all, HVAC expenses can add up to a big portion of your monthly electric bill. To figure out new ways to lower their HVAC bill, some homeowners look closely at their thermostat. Could there be a setting they can use to improve efficiency?

Most thermostats come with a ‘Fan’ or ‘Fan On’ setting. But if the fan is going during a normal cycle, what can the fan setting provide for your HVAC system? This guide should help. We’ll share precisely what the fan setting is and how you can use it to reduce costs in 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 remains on. Certain furnaces will operate at a low level in this setting, but for the most part heating or cooling isn’t being made. The ‘Auto’ setting, in contrast, will start the fan over a heating or cooling cycle and turn it off when the cycle is over.

There are advantages and disadvantages to switching on the fan setting on your thermostat, and whether you do or don’t {will|can|should]] depend on your distinct comfort preferences.

Advantages to switching to the Fan/On setting:

  • You can keep the temperature throughout your home more balanced by enabling the fan to keep generating airflow.
  • Indoor air quality should improve as steady airflow will keep moving airborne particles into the air filter.
  • A smaller amount of start-stop cycles for the blower fan helps extend its life span. As the air handler is usually connected to the furnace, this means you could minimize the risk of needing furnace repair.

Downsides to switching to the Fan/On setting:

  • A constant fan will likely increase your energy expenses somewhat.
  • Constant airflow may clog your air filter soon, increasing the frequency you will want to replace it.

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 keep the fan running, your HVAC system can draw this warm air into the rest of your home, pushing the HVAC system to work harder to maintain the desired temperature. In severe heat, this could result in needing AC repair more often as wear and tear grows.

The reverse can happen during the winter. Cooler spaces like a basement will hold onto cooler air, which can eventually drift into the rest of your home. Leaving the fan running may pump more cold air upward, increasing the amount of heating you need to stay warm.

If you’re still trying to figure out 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 ideal for you if:

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

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