Once the weather is cooling off, you might be thinking about how you’ll prepare your heating and cooling. After all, HVAC costs routinely make up a large piece of your monthly electric bill. To learn new ways to lower their HVAC bill, some people look closer at their thermostat. Maybe there’s a setting they should use to boost efficiency?

Most thermostats include both a ‘Fan’ or ‘Fan On’ setting. But if the fan is on during a normal cycle, what does the fan setting offer for an HVAC system? This guide will help. We’ll walk through just what the fan setting is and when you can use it to cut costs during the summer or winter.

What Is the Fan Setting on My Thermostat?

For most thermostats, the fan setting indicates that the HVAC blower fan keeps running. Some furnaces may continue to operate at a low level with this setting, but in general heating or cooling isn’t being produced. The ‘Auto’ setting, conversely, will turn on the fan during a heating or cooling cycle and turn it off once the cycle is complete.

There are pros and cons to using the fan setting on your thermostat, and whether you do or don’t {will|can|should]] depend on your unique comfort needs.

Advantages to utilizing the Fan/On setting:

  • You can keep the temperature throughout your home more balanced by enabling the fan to keep circulating air.
  • Indoor air quality can increase because constant airflow will keep forcing airborne pollutants through the air filter.
  • A smaller number of start-stop cycles for the blower fan helps extend its life span. Because the air handler is typically a component of the furnace, this means you can prevent the need for furnace repair.

Disadvantages to switching to the Fan/On setting:

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

{Choosing Between|Should My Thermostat Be on|Which Setting for My Thermostat? Fan or Auto in Each Season

Through the summer, warm air will sometimes persist 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, forcing the HVAC system to work more to maintain the desired temperature. In severe heat, this can lead to needing AC repair more quickly as wear and tear gets worse.

The opposite can occur during the winter. Cooler spaces like a basement will hold onto cooler air, which may eventually drift 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 figure out if you should switch to the fan/on setting, remember that every home and family’s comfort needs are different. Leaving the HVAC system’s fan on could be best for you if:

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

Your home has hot and cold spots. Lots of homes wrestle with persistent hot and cold spots that quickly return to a temperature different from the rest of the house. The fan setting might help lessen these changes by consistently refreshing each room’s ventilation.