When the weather begins to cool off, you might be concerned about how you’ll take full advantage of your heating and cooling. After all, HVAC costs frequently add up to a large piece of your monthly electric bill. To figure out new ways to lower their HVAC bill, some owners look closer at their thermostat. Maybe there’s a setting they should use to improve efficiency?

Most thermostats come with a ‘Fan’ or ‘Fan On’ setting. But if the fan is running during a normal cycle, what can the fan setting offer for the HVAC system? This guide will help. We’ll walk through precisely 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 indicates that the HVAC blower fan keeps running. A few furnaces may continue to generate heat at a low level with this setting, but in general heating or cooling isn’t being generated. The ‘Auto’ setting, on the other hand, will turn on the fan over a heating or cooling cycle and turn it off after the cycle is finished.

There are advantages and disadvantages to switching on 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 in each room more balanced by allowing the fan to keep running.
  • Indoor air quality will be highest because steady airflow will keep forcing airborne contaminants 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 part of the furnace, this means you can minimize the risk of needing furnace repair.

Drawbacks to using the Fan/On setting:

  • A continuous fan could add to your energy costs slightly.
  • Constant airflow may clog your air filter soon, increasing the frequency you’ll need to replace it.

Which Setting for My Thermostat? Fan or Auto in Summer/Winter

During the summer, warm air can persist in unfinished spaces such as the attic or an attached garage. If you leave the fan on, your HVAC system can gradually move this warm air into the rest of your home, compelling the HVAC system to work harder to keep up with the desired temperature. In severe heat, this may result in needing AC repair more regularly as wear and tear grows.

The opposite can happen over 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. Keeping the fan on could pull more cold air upward, increasing the amount of heating you need to stay 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 are different. Leaving the HVAC system’s fan on may work for you if:

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

Your home has hot and cold spots. Lots 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 limit these changes by consistently refreshing each room’s supply of air.