As the weather begins to cool off, you may be wondering about how you’ll prepare your heating and cooling. After all, HVAC bills can contribute a large piece of your monthly electric bill. To figure out new ways to save, some people 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 on during a normal cycle, what does the fan setting provide for the HVAC system? This guide will help. We’ll walk through what exactly the fan setting is and when you can use it to save money in the summer or winter.

What Is the Fan Setting on My Thermostat?

For most thermostats, the fan setting indicates that the system’s blower fan stays on. Certain furnaces will generate heat at a low level with this setting, but for the most part heating or cooling isn’t being generated. The ‘Auto’ setting, in contrast, will run the fan over a heating or cooling cycle and shut it off when the cycle is finished.

There are benefits and drawbacks to switching on the fan setting on your thermostat, and whether you do or don’t {will|can|should]] depend on your distinct comfort preferences.

Advantages to using the Fan/On setting:

  • You can keep the temperature in every room more uniform by allowing the fan to keep generating airflow.
  • Indoor air quality will be highest as continuous airflow will keep forcing airborne pollutants through the air filter.
  • Fewer start-stop cycles for the blower fan helps extend its life span. As the air handler is typically a component of the furnace, this means you might prevent the need for furnace repair.

Downsides to using the Fan/On setting:

  • A continuous fan can add to your energy costs slightly.
  • Nonstop airflow could clog your air filter in a shorter amount of time, increasing the frequency you will want to replace it.

Which Setting for My Thermostat? Fan or Auto in Each Season

During the summer, warm air can linger in unfinished spaces including the attic or an attached garage. If you use the fan setting, your HVAC system may gradually move this warm air into the rest of your home, forcing the HVAC system to work harder to preserve the preferred temperature. In severe heat, this may lead to needing AC repair more quickly as wear and tear gets worse.

The reverse can occur during 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. Leaving the fan running may 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 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 could be ideal for you if:

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

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