As the weather starts to cool off, you may be concerned about how you’ll take full advantage of your heating and cooling. After all, HVAC bills routinely add up to a significant chunk of your monthly electric bill. To try and find ways to reduce costs, some owners look closely at their thermostat. Maybe there’s a setting they can use to increase efficiency?

Most thermostats come with a ‘Fan’ or ‘Fan On’ setting. But if the fan is running during a normal cycle, what does the fan setting offer for the HVAC system? This guide will help. We’ll walk through precisely what the fan setting is and when you can use it to reduce costs over the summer or winter.

Should I Use My Thermostat's Fan Setting?

For the bulk of thermostats, the fan setting means that the system's blower fan stays on. Certain furnaces will generate heat at a low level in this setting, but in general heating or cooling isn’t being generated. 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 finished.

There are pros and cons to switching on the fan setting on your thermostat, and whether you do or don’t {will|can|should]] depend on your distinct comfort requirements.

Advantages to trying the Fan/On setting:

  • You can keep the temperature throughout your home more uniform by permitting the fan to keep running.
  • Indoor air quality can increase as constant airflow will keep passing airborne particles through the air filter.
  • Fewer start-stop cycles for the system's fan helps expand its life span. As the air handler is typically a component of the furnace, this means you can prevent the need for furnace repair.

Downsides to switching to the Fan/On setting:

  • A continuous fan could increase your energy bills by a small margin.
  • Constant airflow may clog your air filter soon, increasing the frequency you should replace it.

{Choosing Between|Should My Thermostat Be on|Which Setting for My Thermostat? Fan or Auto in Summer/Winter

In the summer, warm air may stick around in unfinished spaces like the attic or an attached garage. If you keep the fan running, your HVAC system can pull this warm air into the rest of your home, forcing the HVAC system to run longer to keep up with the set temperature. In extreme heat, this may lead to needing AC repair more quickly as wear and tear gets worse.

The reverse can happen during the winter. Cooler spaces like a basement will hold onto cooler air, which can 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 keep warm.

If you’re still trying to figure out if you should switch to 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 be ideal for you if:

Someone in your household has allergies. Allergies and other respiratory conditions can be stressful on the family. Leaving the fan on is more likely to enhance indoor air quality, helping your family breathe easier.

Your home deals with hot and cold spots. Many homes deal with persistent hot and cold spots that quickly evolve to a temperature different from the rest of the house. The fan setting should help minimize these changes by steadily refreshing each room’s airflow.