When the weather is cooling off, you might be thinking about how you’ll make the most of your heating and cooling. After all, HVAC costs frequently add up to a big piece of your monthly electric bill. To figure out new ways to lower their HVAC bill, some people take a closer look at their thermostat. Is there a setting they should use to improve efficiency?

Most thermostats come with a ‘Fan’ or ‘Fan On’ setting. But if the fan is on during a typical cycle, what will the fan setting provide for your HVAC system? This guide can help. We’ll share what exactly the fan setting is and whether you can use it to reduce costs over the summer or winter.

What Is the Fan Setting on My Thermostat?

For the majority of thermostats, the fan setting means that the air handler’s blower fan keeps running. A few furnaces can operate at a low level with this setting, but for the most part heating or cooling isn’t being generated. The ‘Auto’ setting, conversely, will start the fan over a heating or cooling cycle and shut it off after the cycle is complete.

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

Advantages to switching to the Fan/On setting:

  • You can keep the temperature throughout your home more uniform by permitting the fan to keep generating airflow.
  • Indoor air quality can increase because continuous airflow will keep passing airborne particles into the air filter.
  • Fewer start-stop cycles for the HVAC fan helps expand its life span. As the air handler is usually a component of the furnace, this means you could avoid needing furnace repair.

Downsides to using the Fan/On setting:

  • A continuous fan could increase your energy costs slightly.
  • Continuous 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 will sometimes persist in unfinished spaces like the attic or an attached garage. If you leave the fan on, your HVAC system may pull this warm air into the rest of your home, forcing the HVAC system to work more to preserve the desired temperature. In severe heat, this may result in needing AC repair more often as wear and tear gets worse.

The reverse can happen in the winter. Cooler spaces such as a basement will hold onto cooler air, which will eventually make its way into the rest of your home. Leaving the fan setting on may 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, don’t forget that every home and family’s comfort needs will vary. Leaving the HVAC system’s fan on may be ideal 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 experiences hot and cold spots. Many homes deal with stubborn hot and cold spots that quickly evolve to a temperature different from the rest of the house. The fan setting can help limit these changes by constantly refreshing each room’s supply of air.