As the weather is cooling off, you may be wondering about how you’ll make the most of your heating and cooling. After all, HVAC costs can make up a significant portion of your monthly electric bill. To try and find ways to lower their HVAC bill, some homeowners look closer at their thermostat. Maybe there’s a setting they can 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 will the fan setting offer for the 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.

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 will run at a low level with this setting, but in most cases heating or cooling isn’t being produced. The ‘Auto’ setting, on the other hand, will turn on the fan over a heating or cooling cycle and shut it off after the cycle is complete.

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

Advantages to utilizing the Fan/On setting:

  • You can keep the temperature in every room more uniform by enabling the fan to keep running.
  • Indoor air quality will be highest as continuous airflow will keep passing airborne particles into 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 typically a component of the furnace, this means you might avoid needing furnace repair.

Downsides to utilizing the Fan/On setting:

  • A constant fan can add to your energy costs by a small margin.
  • Constant airflow could clog your air filter soon, increasing the frequency you will want to replace it.

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

Through the summer, warm air may persist in unfinished spaces including the attic or an attached garage. If you keep the fan running, your HVAC system may gradually move this warm air into the rest of your home, pushing the HVAC system to work harder to keep up with the desired temperature. In serious heat, this could result in needing AC repair more regularly as wear and tear increases.

The reverse can take place during the winter. Cooler spaces such as a basement will hold onto cooler air, which may eventually make its way into the rest of your home. Leaving the fan running will sometimes pull more cold air upward, increasing the amount of heating you need to remain warm.

If you’re still trying to determine 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 be ideal 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 can help to improve indoor air quality, helping your family breathe easier.

Your home experiences hot and cold spots. All kinds of homes deal with difficult hot and cold spots that quickly evolve to a temperature different from the rest of the house. The fan setting can help lessen these changes by constantly refreshing each room’s airflow.