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 bills can contribute a big chunk of your monthly electric bill. To learn new ways to save, some homeowners look closely at their thermostat. Maybe there’s a setting they should use to increase efficiency?

The bulk of thermostats have a ‘Fan’ or ‘Fan On’ setting. But if the fan is running during a typical cycle, what does the fan setting provide for your HVAC system? This guide can help. We’ll review what exactly the fan setting is and how you can use it to save money during the summer or winter.

What Is the Fan Setting on My Thermostat?

For the bulk of thermostats, the fan setting signifies that the air handler’s blower fan keeps running. Certain furnaces will generate heat at a low level with this setting, but in general heating or cooling isn’t being made. The ‘Auto’ setting, conversely, will start the fan during a heating or cooling cycle and shut it off after the cycle is over.

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

Advantages to trying the Fan/On setting:

  • You can keep the temperature in each room more balanced by allowing the fan to keep running.
  • Indoor air quality should improve because continuous airflow will keep moving airborne contaminants through the air filter.
  • A smaller number of start-stop cycles for the HVAC fan helps lengthen its life span. As the air handler is often a component of the furnace, this means you could prevent the need for furnace repair.

Disadvantages to utilizing the Fan/On setting:

  • A continuous fan can increase your energy costs by a small margin.
  • Nonstop airflow may clog your air filter soon, increasing the frequency you will want to replace it.

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

During the summer, warm air will sometimes persist in unfinished spaces including the attic or an attached garage. If you leave the fan on, your HVAC system may draw this warm air into the rest of your home, compelling the HVAC system to run longer to keep up with the set temperature. In serious heat, this could lead to needing AC repair more regularly as wear and tear gets worse.

The reverse can happen in the winter. Cooler spaces such as a basement will hold onto cooler air, which can eventually make its way into the rest of your home. Keeping the fan on will sometimes draw more cold air upward, increasing the amount of heating you need to stay warm.

If you’re still trying to decide 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 could be best for you if:

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

Your home experiences hot and cold spots. Lots of homes deal with difficult hot and cold spots that quickly shift to a temperature different from the rest of the house. The fan setting can help limit these changes by consistently refreshing each room’s supply of air.