As the weather is cooling off, you are probably concerned about how you’ll take full advantage of your heating and cooling. After all, HVAC costs routinely make up a large chunk of your monthly electric bill. To figure out new ways to reduce costs, some homeowners take a closer look at their thermostat. Could there be a setting they can use to improve efficiency?

The majority 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 the HVAC system? This guide will help. We’ll review just what the fan setting is and when you can use it to cut costs during the summer or winter.

Should I Use My Thermostat's Fan Setting?

For most thermostats, the fan setting indicates that the HVAC blower fan keeps running. Certain furnaces may continue to generate heat at a low level in this setting, but for the most part heating or cooling isn’t being generated. The ‘Auto’ setting, in contrast, will turn on the fan over a heating or cooling cycle and shut it off once the cycle is finished.

There are pros and cons to using the fan setting on your thermostat, and the ideal option {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 allowing the fan to keep generating airflow.
  • Indoor air quality will be highest as continuous airflow will keep forcing airborne contaminants through the air filter.
  • A smaller amount of start-stop cycles for the HVAC fan helps expand its life span. Because the air handler is often part of the furnace, this means you can minimize the risk of needing furnace repair.

Drawbacks to using the Fan/On setting:

  • A nonstop fan will likely raise your energy costs somewhat.
  • Constant airflow may clog your air filter in a shorter amount of time, increasing the frequency you’ll need to replace it.

{Choosing Between|Should My Thermostat Be on|Which Setting for My Thermostat? Fan or Auto in Each Season

In the summer, warm air may persist in unfinished spaces including the attic or an attached garage. If you use the fan setting, your HVAC system might gradually move this warm air into the rest of your home, forcing the HVAC system to work more to maintain the set temperature. In extreme heat, this could result in needing AC repair more regularly as wear and tear gets worse.

The reverse can occur in the winter. Cooler spaces like a basement will hold onto cooler air, which can eventually flow into the rest of your home. Leaving the fan running will sometimes draw more cold air upward, increasing the amount of heating you need to stay warm.

If you’re still trying to decide if you should switch to the fan/on setting, don’t forget that every home and family’s comfort needs will vary. Leaving the HVAC system’s fan on may be best for you if:

Someone in your household deals with allergies. Allergies and similar 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. Many homes wrestle with persistent 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 constantly refreshing each room’s supply of air.