As the weather starts to cool off, you may be thinking about how you’ll take full advantage of your heating and cooling. After all, HVAC expenses routinely contribute a large piece of your monthly electric bill. To figure out new ways to reduce costs, some owners look closer at their thermostat. Maybe there’s a setting they can use to increase efficiency?

The bulk of thermostats include both a ‘Fan’ or ‘Fan On’ setting. But if the fan is on during a normal cycle, what does the fan setting provide for an HVAC system? This guide can help. We’ll review just what the fan setting is and when you can use it to cut costs in the summer or winter.

What Is the Fan Setting on My Thermostat?

For most thermostats, the fan setting means that the air handler’s blower fan stays on. A few furnaces may continue to generate heat at a low level with this setting, but for the most part heating or cooling isn’t being made. The ‘Auto’ setting, on the other hand, will start the fan during a heating or cooling cycle and turn 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 requirements.

Advantages to switching to the Fan/On setting:

  • You can keep the temperature in each room more balanced by permitting the fan to keep running.
  • Indoor air quality should improve because steady airflow will keep passing airborne contaminants into the air filter.
  • Fewer start-stop cycles for the system's fan helps lengthen its life span. As the air handler is often connected to the furnace, this means you might prevent the need for furnace repair.

Drawbacks to utilizing the Fan/On setting:

  • A constant fan will likely raise your energy costs slightly.
  • Nonstop airflow can clog your air filter soon, 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 Each Season

During the summer, warm air may stick around in unfinished spaces like the attic or an attached garage. If you leave the fan on, your HVAC system might gradually move this warm air into the rest of your home, compelling the HVAC system to run longer to keep up with the preferred temperature. In extreme heat, this may lead to needing AC repair more often as wear and tear increases.

The reverse can take place over the winter. Cooler spaces like a basement will hold onto cooler air, which will eventually flow into the rest of your home. Leaving the fan setting on could pull more cold air upward, increasing the amount of heating you need to stay warm.

If you’re still trying to decide if you should try the fan/on setting, don’t forget that every home and family’s comfort needs are not the same. Leaving the HVAC system’s fan on could work 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 is more likely to increase indoor air quality, helping your family breathe easier.

Your home experiences hot and cold spots. All kinds of homes wrestle with stubborn hot and cold spots that quickly return to a temperature different from the rest of the house. The fan setting should help lessen these changes by constantly refreshing each room’s supply of air.