Once the weather starts to cool off, you may be concerned about how you’ll take full advantage of your heating and cooling. After all, HVAC expenses can contribute a big chunk of your monthly electric bill. To try and find ways to lower their HVAC bill, some homeowners take a closer look at their thermostat. Is there a setting they could use to increase efficiency?

The bulk of thermostats come with a ‘Fan’ or ‘Fan On’ setting. But if the fan is going during a regular cycle, what does the fan setting provide for the HVAC system? This guide should help. We’ll share just what the fan setting is and how you can use it to save money during the summer or winter.

What Is the Fan Setting on My Thermostat?

For the bulk of thermostats, the fan setting means that the air handler’s blower fan keeps running. Some furnaces may continue to generate heat at a low level in this setting, but in most cases heating or cooling isn’t being generated. The ‘Auto’ setting, in contrast, will start the fan through a heating or cooling cycle and switch it off when the cycle is over.

There are advantages and disadvantages to trying the fan setting on your thermostat, and what's ideal {will|can|should]] depend on your distinct comfort requirements.

Advantages to using the Fan/On setting:

  • You can keep the temperature in every room more balanced by permitting the fan to keep running.
  • Indoor air quality should improve as continuous airflow will keep moving airborne particles into the air filter.
  • A smaller number of start-stop cycles for the HVAC fan helps expand its life span. Since the air handler is usually part of the furnace, this means you can prevent the need for furnace repair.

Downsides to using the Fan/On setting:

  • A constant fan could increase your energy bills by a small margin.
  • Constant airflow can clog your air filter up more quickly, increasing the frequency you should replace it.

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

Through the summer, warm air may stick around in unfinished spaces including the attic or an attached garage. If you keep the fan running, your HVAC system may draw this warm air into the rest of your home, compelling the HVAC system to run longer to preserve the desired temperature. In severe heat, this may result in needing AC repair more regularly as wear and tear gets worse.

The opposite can occur in the winter. Cooler spaces such as a basement will hold onto cooler air, which can eventually flow into the rest of your home. Keeping the fan on may pump more cold air upward, increasing the amount of heating you need to remain warm.

If you’re still trying to figure out if you should try the fan/on setting, remember that every home and family’s comfort needs are different. Leaving the HVAC system’s fan on may 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 is more likely to enhance indoor air quality, helping your family breathe easier.

Your home deals with hot and cold spots. All kinds of homes wrestle with persistent hot and cold spots that quickly shift 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.