As the weather starts to cool off, you might be concerned about how you’ll prepare your heating and cooling. After all, HVAC bills frequently add up to a significant chunk of your monthly electric bill. To try and find ways to lower their HVAC bill, some homeowners look closely at their thermostat. Could there be a setting they could use to boost efficiency?

The bulk of thermostats come with a ‘Fan’ or ‘Fan On’ setting. But if the fan is on during a normal cycle, what will the fan setting offer for the HVAC system? This guide will help. We’ll walk through what exactly 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 most thermostats, the fan setting indicates that the air handler’s blower fan stays on. Certain furnaces can generate heat at a low level with this setting, but in most cases heating or cooling isn’t being made. The ‘Auto’ setting, in contrast, will start the fan over a heating or cooling cycle and switch it off after the cycle is complete.

There are benefits and drawbacks to switching on the fan setting on your thermostat, and the ideal option {will|can|should]] depend on your unique comfort preferences.

Advantages to using the Fan/On setting:

  • You can keep the temperature in each room more uniform by permitting the fan to keep running.
  • Indoor air quality can increase since continuous airflow will keep forcing airborne particles into the air filter.
  • Fewer start-stop cycles for the system's fan helps extend its life span. Because the air handler is usually connected to the furnace, this means you could avoid needing furnace repair.

Downsides to using the Fan/On setting:

  • A constant fan can raise your energy bills by a small margin.
  • Continuous airflow could 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

During the summer, warm air may linger in unfinished spaces including the attic or an attached garage. If you use the fan setting, your HVAC system can pull this warm air into the rest of your home, compelling the HVAC system to run longer to keep up with the set temperature. In severe heat, this may result in needing AC repair more quickly as wear and tear gets worse.

The reverse can take place 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. Keeping the fan 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, keep in mind that every home and family’s comfort needs will vary. 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 tough on the family. Leaving the fan on is more likely to improve indoor air quality, helping your family breathe easier.

Your home has hot and cold spots. Many homes deal with stubborn hot and cold spots that quickly evolve to a temperature different from the rest of the house. The fan setting should help lessen these changes by constantly refreshing each room’s supply of air.