As the weather starts to cool off, you might be concerned about how you’ll take full advantage of your heating and cooling. After all, HVAC bills routinely make up a significant chunk of your monthly electric bill. To learn new ways to lower their HVAC bill, some people look closely at their thermostat. Maybe there’s a setting they should use to improve efficiency?

The bulk of thermostats have a ‘Fan’ or ‘Fan On’ setting. But if the fan is on during a normal cycle, what can the fan setting provide for an HVAC system? This guide should help. We’ll walk through what exactly the fan setting is and when you can use it to cut costs over the summer or winter.

Should I Use My Thermostat’s Fan Setting?

For the majority of thermostats, the fan setting signifies that the air handler’s blower fan stays on. Certain furnaces can run at a low level with this setting, but for the most part heating or cooling isn’t being produced. The ‘Auto’ setting, conversely, will turn on the fan through a heating or cooling cycle and turn it off when the cycle is over.

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 personal comfort requirements.

Advantages to using 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 should improve since constant airflow will keep moving 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 often a component of the furnace, this means you could avoid needing furnace repair.

Drawbacks to switching to the Fan/On setting:

  • A constant fan will likely increase your energy bills slightly.
  • Nonstop airflow could clog your air filter up more quickly, increasing the frequency you’ll need to replace it.

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

In the summer, warm air will sometimes persist in unfinished spaces such as the attic or an attached garage. If you use the fan setting, your HVAC system might pull this warm air into the rest of your home, forcing the HVAC system to work harder to preserve the preferred temperature. In extreme heat, this could lead to needing AC repair more quickly as wear and tear gets worse.

The opposite can happen 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 will sometimes pump more cold air upward, increasing the amount of heating you need to stay warm.

If you’re still trying to figure out if you should switch to the fan/on setting, don’t forget that every home and family’s comfort needs are different. Leaving the HVAC system’s fan on might be ideal for you if:

Someone in your household deals with allergies. Allergies and similar 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 has hot and cold spots. Lots of homes deal with difficult hot and cold spots that quickly return to a temperature different from the rest of the house. The fan setting can help lessen these changes by constantly refreshing each room’s supply of air.