Once the weather is cooling off, you may be wondering about how you’ll make the most of your heating and cooling. After all, HVAC costs frequently make up a big portion of your monthly electric bill. To try and find ways to reduce costs, some owners look closer at their thermostat. Could there be a setting they can use to increase efficiency?

The majority of thermostats have a ‘Fan’ or ‘Fan On’ setting. But if the fan is going during a normal cycle, what will the fan setting provide for your HVAC system? This guide will help. We’ll review what exactly the fan setting is and how you can use it to cut costs in the summer or winter.

What Is the Fan Setting on My Thermostat?

For the bulk of thermostats, the fan setting signifies that the system's blower fan remains on. A few furnaces may continue to run at a low level in this setting, but in general heating or cooling isn’t being produced. The ‘Auto’ setting, in contrast, will start the fan through a heating or cooling cycle and switch it off after the cycle is finished.

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

Advantages to using the Fan/On setting:

  • You can keep the temperature in every room more uniform by allowing the fan to keep running.
  • Indoor air quality should improve as constant airflow will keep forcing airborne pollutants into the air filter.
  • Fewer start-stop cycles for the blower fan helps extend its life span. Since the air handler is usually part of the furnace, this means you could prevent the need for furnace repair.

Downsides to switching to the Fan/On setting:

  • A continuous fan could raise your energy bills by a small margin.
  • Nonstop airflow can clog your air filter in a shorter amount of time, 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 will sometimes persist in unfinished spaces including the attic or an attached garage. If you keep the fan running, your HVAC system can draw this warm air into the rest of your home, forcing the HVAC system to work more to preserve the desired temperature. In extreme heat, this may lead to needing AC repair more often as wear and tear gets worse.

The reverse can happen over the winter. Cooler spaces like 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 draw more cold air upward, increasing the amount of heating you need to stay warm.

If you’re still trying to figure out if you should use the fan/on setting, remember that every home and family’s comfort needs will vary. Leaving the HVAC system’s fan on may work for you if:

Someone in your household deals with allergies. Allergies and other respiratory conditions can be hard 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. All kinds of homes deal with difficult hot and cold spots that quickly return to a temperature different from the rest of the house. The fan setting might help lessen these changes by constantly refreshing each room’s supply of air.