Once the weather begins to cool off, you may be thinking about how you’ll prepare your heating and cooling. After all, HVAC bills routinely make up a big piece of your monthly electric bill. To try and find ways to save, some people look closely at their thermostat. Maybe there’s a setting they can use to improve efficiency?

The bulk of thermostats include both a ‘Fan’ or ‘Fan On’ setting. But if the fan is going during a normal cycle, what does the fan setting provide for your HVAC system? This guide should help. We’ll walk through just what the fan setting is and when 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 signifies that the system’s blower fan remains on. Certain furnaces may continue to run at a low level with this setting, but in most cases heating or cooling isn’t being produced. The ‘Auto’ setting, in contrast, will run the fan over a heating or cooling cycle and shut it off once the cycle is over.

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

Advantages to using the Fan/On setting:

  • You can keep the temperature in each room more uniform by enabling the fan to keep running.
  • Indoor air quality should improve as 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. Since the air handler is usually part of the furnace, this means you could minimize the risk of needing furnace repair.

Drawbacks to using the Fan/On setting:

  • A constant fan could raise your energy expenses by a small margin.
  • Constant airflow may clog your air filter soon, increasing the frequency you’ll need to replace it.

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

In the summer, warm air will sometimes linger in unfinished spaces like the attic or an attached garage. If you keep the fan running, your HVAC system can gradually move this warm air into the rest of your home, compelling the HVAC system to work harder to maintain the desired temperature. In severe heat, this could lead to needing AC repair more quickly as wear and tear gets worse.

The opposite can take place in the winter. Cooler spaces like a basement will hold onto cooler air, which can eventually flow into the rest of your home. Keeping the fan on could 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 use the fan/on setting, keep in mind that every home and family’s comfort needs are different. Leaving the HVAC system’s fan on could work for you if:

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

Your home has hot and cold spots. All kinds 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 limit these changes by steadily refreshing each room’s supply of air.