When the weather starts to cool off, you may be thinking about how you’ll make the most of your heating and cooling. After all, HVAC bills can add up to a big chunk of your monthly electric bill. To learn new ways to lower their HVAC bill, some owners look closer at their thermostat. Could there be a setting they could use to improve efficiency?

Most thermostats come with a ‘Fan’ or ‘Fan On’ setting. But if the fan is going during a regular cycle, what does the fan setting provide for your HVAC system? This guide should help. We’ll share just what the fan setting is and whether you can use it to reduce 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 remains on. Certain furnaces may continue to generate heat at a low level in this setting, but for the most part heating or cooling isn’t being generated. The ‘Auto’ setting, on the other hand, will run the fan through a heating or cooling cycle and shut it off when the cycle is complete.

There are pros and cons to trying the fan setting on your thermostat, and what's ideal {will|can|should]] depend on your distinct comfort preferences.

Advantages to utilizing the Fan/On setting:

  • You can keep the temperature in every room more balanced by enabling the fan to keep generating airflow.
  • Indoor air quality will be highest as steady airflow will keep moving airborne pollutants into the air filter.
  • Fewer start-stop cycles for the blower fan helps extend its life span. Since the air handler is usually part of the furnace, this means you could avoid needing furnace repair.

Disadvantages to using the Fan/On setting:

  • A constant fan will likely increase your energy bills by a small margin.
  • Continuous airflow can clog your air filter soon, increasing the frequency you should replace it.

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

During the summer, warm air will sometimes stick around in unfinished spaces including the attic or an attached garage. If you leave the fan on, your HVAC system might draw this warm air into the rest of your home, compelling the HVAC system to run longer to preserve the preferred temperature. In serious heat, this may lead to needing AC repair more quickly as wear and tear grows.

The reverse can take place over the winter. Cooler spaces such as a basement will hold onto cooler air, which can eventually flow 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 remain warm.

If you’re still trying to decide if you should switch to the fan/on setting, don’t forget that every home and family’s comfort needs will vary. Leaving the HVAC system’s fan on might be best for you if:

Someone in your household deals with allergies. Allergies and similar respiratory conditions can be hard on the family. Leaving the fan on is more likely to increase indoor air quality, helping your family breathe easier.

Your home has hot and cold spots. Many 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 ventilation.