Once the weather starts to cool off, you may be wondering about how you’ll take full advantage of your heating and cooling. After all, HVAC bills frequently add up to a large chunk of your monthly electric bill. To figure out new ways to lower their HVAC bill, some people look closer at their thermostat. Maybe there’s a setting they should use to improve efficiency?

The majority of thermostats come with a ‘Fan’ or ‘Fan On’ setting. But if the fan is running during a regular cycle, what does the fan setting offer for an HVAC system? This guide can help. We’ll walk through precisely what the fan setting is and when you can use it to reduce costs during the summer or winter.

My Thermostat Has a Fan Setting?

For most thermostats, the fan setting indicates that the system’s blower fan remains on. A few furnaces can operate at a low level with this setting, but in general heating or cooling isn’t being made. The ‘Auto’ setting, conversely, will run the fan during a heating or cooling cycle and switch it off after the cycle is over.

There are pros and cons to using the fan setting on your thermostat, and whether you do or don’t {will|can|should]] depend on your personal comfort requirements.

Advantages to using the Fan/On setting:

  • You can keep the temperature in every room more uniform by enabling the fan to keep circulating air.
  • Indoor air quality will be highest as continuous airflow will keep forcing airborne contaminants through the air filter.
  • Fewer start-stop cycles for the system’s fan helps extend its life span. Since the air handler is usually connected to the furnace, this means you could prevent the need for furnace repair.

Disadvantages to utilizing the Fan/On setting:

  • A nonstop fan will likely increase your energy costs slightly.
  • Nonstop airflow may clog your air filter in a shorter amount of time, increasing the frequency you will want to replace it.

{Choosing Between|Should My Thermostat Be on|Which Setting for My Thermostat? Fan or Auto in Summer/Winter

During the summer, warm air will sometimes linger in unfinished spaces like the attic or an attached garage. If you use the fan setting, your HVAC system may draw this warm air into the rest of your home, pushing the HVAC system to run longer to maintain the preferred temperature. In extreme heat, this could lead to needing AC repair more quickly as wear and tear grows.

The opposite can happen over the winter. Cooler spaces like a basement will hold onto cooler air, which will eventually flow 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 remain warm.

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

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

Your home deals with hot and cold spots. All kinds of homes deal with difficult hot and cold spots that quickly evolve 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.