As the weather begins to cool off, you might be thinking about how you’ll prepare your heating and cooling. After all, HVAC costs frequently contribute a large chunk of your monthly electric bill. To figure out new ways to lower their HVAC bill, some people look closer at their thermostat. Maybe there’s a setting they could 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 can the fan setting offer for an HVAC system? This guide will help. We’ll review 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 majority of thermostats, the fan setting indicates that the HVAC blower fan stays on. A few furnaces can generate heat at a low level in this setting, but in most cases heating or cooling isn’t being generated. The ‘Auto’ setting, in contrast, will start the fan during a heating or cooling cycle and turn it off when the cycle is over.

There are pros and cons to using the fan setting on your thermostat, and what's ideal {will|can|should]] depend on your personal comfort requirements.

Advantages to using the Fan/On setting:

  • You can keep the temperature in every room more uniform by permitting the fan to keep running.
  • Indoor air quality should improve because steady airflow will keep passing airborne contaminants through the air filter.
  • A smaller number of start-stop cycles for the system's fan helps extend its life span. Because the air handler is often a component of the furnace, this means you can minimize the risk of needing furnace repair.

Downsides to switching to the Fan/On setting:

  • A nonstop fan can add to your energy bills by a small margin.
  • Nonstop airflow could clog your air filter up more quickly, increasing the frequency you will want to replace it.

Should My Thermostat Be on Fan or Auto in Summer/Winter

During the summer, warm air may linger in unfinished spaces such as the attic or an attached garage. If you use the fan setting, your HVAC system may pull this warm air into the rest of your home, compelling the HVAC system to work harder to maintain the desired temperature. In severe heat, this could result in needing AC repair more often as wear and tear gets worse.

The opposite can occur 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 running could draw more cold air upward, increasing the amount of heating you need to remain warm.

If you’re still trying to determine if you should switch to the fan/on setting, keep in mind 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 deals with allergies. Allergies and similar respiratory conditions can be stressful on the family. Leaving the fan on should help to improve indoor air quality, helping your family breathe easier.

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