When the weather is cooling off, you might be concerned about how you’ll prepare your heating and cooling. After all, HVAC expenses frequently make up a large piece of your monthly electric bill. To learn new ways to save, some people look closely at their thermostat. Maybe there’s a setting they can use to improve efficiency?

The majority of thermostats have a ‘Fan’ or ‘Fan On’ setting. But if the fan is running during a typical cycle, what can the fan setting provide for an HVAC system? This guide should help. We’ll walk through precisely what the fan setting is and how 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 air handler’s blower fan keeps running. A few furnaces will 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 start the fan during a heating or cooling cycle and switch it off once the cycle is finished.

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

Advantages to trying the Fan/On setting:

  • You can keep the temperature throughout your home more balanced by permitting the fan to keep circulating air.
  • Indoor air quality can increase as steady airflow will keep forcing airborne pollutants into the air filter.
  • Fewer start-stop cycles for the system's fan helps expand its life span. As the air handler is often a component of the furnace, this means you can avoid needing furnace repair.

Disadvantages to using the Fan/On setting:

  • A constant fan could increase your energy expenses slightly.
  • Constant airflow can 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

In the summer, warm air will sometimes linger in unfinished spaces including the attic or an attached garage. If you use the fan setting, your HVAC system can draw this warm air into the rest of your home, compelling the HVAC system to work harder to preserve the set temperature. In serious heat, this may result in needing AC repair more often as wear and tear grows.

The opposite can occur in the winter. Cooler spaces such as a basement will hold onto cooler air, which may eventually flow into the rest of your home. Leaving the fan setting on could pump 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 try the fan/on setting, don’t forget that every home and family’s comfort needs are not the same. Leaving the HVAC system’s fan on could work for you if:

Someone in your household suffers from allergies. Allergies and similar respiratory conditions can be tough on the family. Leaving the fan on should help to enhance 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 return to a temperature different from the rest of the house. The fan setting can help lessen these changes by steadily refreshing each room’s ventilation.