When the weather starts to cool off, you may be wondering about how you’ll prepare your heating and cooling. After all, HVAC expenses routinely make up a big chunk of your monthly electric bill. To try and find ways to reduce costs, some people look closer at their thermostat. Maybe there’s a setting they could use to boost efficiency?

Most thermostats have a ‘Fan’ or ‘Fan On’ setting. But if the fan is going during a regular cycle, what will the fan setting offer for the HVAC system? This guide can help. We’ll walk through precisely what the fan setting is and whether you can use it to reduce costs in the summer or winter.

What Is the Fan Setting on My Thermostat?

For the majority of thermostats, the fan setting indicates that the air handler’s blower fan keeps running. Some furnaces can generate heat at a low level with this setting, but in most cases heating or cooling isn’t being generated. The ‘Auto’ setting, on the other hand, will run the fan during a heating or cooling cycle and shut it off once the cycle is over.

There are pros and cons to using the fan setting on your thermostat, and the ideal option {will|can|should]] depend on your personal comfort requirements.

Advantages to utilizing the Fan/On setting:

  • You can keep the temperature in each room more consistent by allowing the fan to keep circulating air.
  • Indoor air quality should improve because constant airflow will keep passing airborne particles through the air filter.
  • A smaller number of start-stop cycles for the system's fan helps extend its life span. As the air handler is typically a component of the furnace, this means you could prevent the need for furnace repair.

Disadvantages to using the Fan/On setting:

  • A continuous fan could add to your energy expenses somewhat.
  • Continuous airflow can clog your air filter soon, increasing the frequency you should 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 can linger in unfinished spaces like the attic or an attached garage. If you leave the fan on, your HVAC system might gradually move this warm air into the rest of your home, forcing the HVAC system to run longer to maintain the preferred temperature. In extreme heat, this could result in needing AC repair more often as wear and tear increases.

The reverse can happen in the winter. Cooler spaces like 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 draw more cold air upward, increasing the amount of heating you need to keep warm.

If you’re still trying to decide if you should use the fan/on setting, don’t forget that every home and family’s comfort needs are not the same. Leaving the HVAC system’s fan on may 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 is more likely to enhance indoor air quality, helping your family breathe easier.

Your home experiences hot and cold spots. All kinds of homes deal with stubborn hot and cold spots that quickly return to a temperature different from the rest of the house. The fan setting might help limit these changes by steadily refreshing each room’s ventilation.