Once the weather is cooling off, you may be thinking about how you’ll make the most of your heating and cooling. After all, HVAC bills can contribute a big chunk of your monthly electric bill. To try and find ways to lower their HVAC bill, some owners look closely at their thermostat. Could there be a setting they can use to improve efficiency?

Most thermostats have a ‘Fan’ or ‘Fan On’ setting. But if the fan is running during a normal cycle, what will the fan setting provide for your HVAC system? This guide will help. We’ll share precisely what the fan setting is and how you can use it to save money over the summer or winter.

What Is the Fan Setting on My Thermostat?

For the majority of thermostats, the fan setting signifies that the system's blower fan remains on. Certain furnaces can operate at a low level with this setting, but in most cases heating or cooling isn’t being generated. The ‘Auto’ setting, in contrast, will run the fan over a heating or cooling cycle and shut it off after the cycle is finished.

There are advantages and disadvantages to trying the fan setting on your thermostat, and the ideal option {will|can|should]] depend on your personal comfort needs.

Advantages to switching to the Fan/On setting:

  • You can keep the temperature in each room more consistent by enabling the fan to keep running.
  • Indoor air quality can increase since steady airflow will keep moving airborne contaminants through the air filter.
  • Fewer start-stop cycles for the blower fan helps expand its life span. Since the air handler is typically part of the furnace, this means you can minimize the risk of needing furnace repair.

Disadvantages to switching to the Fan/On setting:

  • A nonstop fan could increase your energy expenses by a small margin.
  • Continuous airflow can clog your air filter in a shorter amount of time, increasing the frequency you’ll need to replace it.

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

In the summer, warm air can persist in unfinished spaces including the attic or an attached garage. If you leave the fan on, your HVAC system might pull this warm air into the rest of your home, compelling the HVAC system to run longer to keep up with the desired temperature. In extreme heat, this could result in needing AC repair more regularly as wear and tear grows.

The opposite can happen during the winter. Cooler spaces such as a basement will hold onto cooler air, which may eventually flow into the rest of your home. Leaving the fan setting on will sometimes pump more cold air upward, increasing the amount of heating you need to keep warm.

If you’re still trying to decide if you should use the fan/on setting, remember that every home and family’s comfort needs are different. Leaving the HVAC system’s fan on could be best for you if:

Someone in your household has allergies. Allergies and other respiratory conditions can be tough 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. Lots of homes deal with difficult 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 steadily refreshing each room’s airflow.