When 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 costs routinely add up to a large piece of your monthly electric bill. To try and find ways to save, some people look closely at their thermostat. Maybe there’s a setting they could use to improve efficiency?

The bulk of thermostats have a ‘Fan’ or ‘Fan On’ setting. But if the fan is running during a normal cycle, what will the fan setting offer for an HVAC system? This guide will help. We’ll share precisely what the fan setting is and whether you can use it to cut costs over the summer or winter.

What Is the Fan Setting on My Thermostat?

For the majority of thermostats, the fan setting indicates that the HVAC blower fan keeps running. Some furnaces will generate heat at a low level in this setting, but in most cases heating or cooling isn’t being made. The ‘Auto’ setting, conversely, will start the fan through a heating or cooling cycle and shut it off after the cycle is complete.

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 personal comfort needs.

Advantages to trying the Fan/On setting:

  • You can keep the temperature in each room more uniform by permitting the fan to keep circulating air.
  • Indoor air quality should improve because continuous airflow will keep passing airborne particles into the air filter.
  • A smaller number of start-stop cycles for the HVAC fan helps expand its life span. As 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 nonstop fan will likely increase your energy costs by a small margin.
  • Nonstop airflow can clog your air filter in a shorter amount of time, increasing the frequency you should replace it.

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

Through the summer, warm air will sometimes stick around in unfinished spaces including the attic or an attached garage. If you keep the fan running, your HVAC system may 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 severe heat, this could lead to needing AC repair more quickly as wear and tear gets worse.

The opposite can happen in 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 setting on could pull more cold air upward, increasing the amount of heating you need to remain warm.

If you’re still trying to determine if you should try 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 has allergies. Allergies and other 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 experiences hot and cold spots. Many homes deal with persistent hot and cold spots that quickly evolve to a temperature different from the rest of the house. The fan setting can help minimize these changes by consistently refreshing each room’s supply of air.