woman adjusting her smart thermostat

When the weather is cooling off, you are probably thinking about how you’ll prepare your heating and cooling. After all, HVAC costs can contribute a large piece of your monthly electric bill. To figure out new ways to lower their HVAC bill, some owners take a closer look at their thermostat. Is there a setting they can use to improve efficiency?

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

Should I Use My Thermostat's Fan Setting?

For the majority of thermostats, the fan setting indicates that the air handler’s blower fan remains on. Some furnaces may continue to generate heat at a low level in this setting, but for the most part heating or cooling isn’t being produced. The ‘Auto’ setting, on the other hand, will start the fan during a heating or cooling cycle and shut it off when the cycle is over.

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

Advantages to trying the Fan/On setting:

  • You can keep the temperature throughout your home more consistent by allowing the fan to keep circulating air.
  • Indoor air quality will be highest since continuous airflow will keep forcing airborne contaminants into the air filter.
  • A smaller amount of start-stop cycles for the HVAC fan helps lengthen its life span. Because the air handler is usually 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 bills by a small margin.
  • Nonstop airflow can clog your air filter up more quickly, 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 Summer/Winter

Through the summer, warm air may stick around in unfinished spaces including the attic or an attached garage. If you use the fan setting, your HVAC system can gradually move this warm air into the rest of your home, forcing the HVAC system to work harder to keep up with the preferred temperature. In severe heat, this could lead to needing AC repair more quickly as wear and tear gets worse.

The reverse can happen 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. Keeping the fan on will sometimes draw more cold air upward, increasing the amount of heating you need to stay warm.

If you’re still trying to decide if you should switch to the fan/on setting, remember that every home and family’s comfort needs will vary. Leaving the HVAC system’s fan on might be ideal for you if:

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

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