Once the weather is cooling off, you may be concerned about how you’ll prepare your heating and cooling. After all, HVAC expenses routinely contribute a big portion of your monthly electric bill. To figure out new ways to lower their HVAC bill, some homeowners take a closer look at their thermostat. Is there a setting they should use to increase efficiency?

The bulk of thermostats include both a ‘Fan’ or ‘Fan On’ setting. But if the fan is going during a normal cycle, what can the fan setting offer for the HVAC system? This guide can help. We’ll review what exactly the fan setting is and when you can use it to save money over the summer or winter.

What Is the Fan Setting on My Thermostat?

For most thermostats, the fan setting means that the air handler’s blower fan stays on. A few furnaces may continue to 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 run the fan over a heating or cooling cycle and turn it off once the cycle is over.

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

Advantages to using the Fan/On setting:

  • You can keep the temperature in each room more balanced by allowing the fan to keep generating airflow.
  • Indoor air quality should improve as constant airflow will keep moving airborne contaminants 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 part of the furnace, this means you could prevent the need for furnace repair.

Downsides to switching to the Fan/On setting:

  • A nonstop fan could raise your energy expenses somewhat.
  • Constant airflow could clog your air filter in a shorter amount of time, increasing the frequency you will want to replace it.

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

In the summer, warm air may linger in unfinished spaces like 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, forcing the HVAC system to work more to maintain the set temperature. In serious heat, this may lead to needing AC repair more quickly as wear and tear grows.

The opposite can occur in the winter. Cooler spaces like a basement will hold onto cooler air, which can eventually flow 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 determine if you should try the fan/on setting, keep in mind that every home and family’s comfort needs are not the same. Leaving the HVAC system’s fan on might be best for you if:

Someone in your household deals with allergies. Allergies and other 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 experiences hot and cold spots. Lots of homes wrestle with stubborn hot and cold spots that quickly shift to a temperature different from the rest of the house. The fan setting can help lessen these changes by constantly refreshing each room’s ventilation.