When the weather begins to cool off, you are probably thinking about how you’ll take full advantage of your heating and cooling. After all, HVAC bills routinely add up to a large piece of your monthly electric bill. To try and find ways to save, some owners take a closer look at their thermostat. Could there be a setting they can use to improve efficiency?

Most thermostats include both a ‘Fan’ or ‘Fan On’ setting. But if the fan is going during a normal cycle, what does the fan setting provide for the HVAC system? This guide can help. We’ll walk through just what the fan setting is and how 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 signifies that the system’s blower fan stays on. Some furnaces will run at a low level with this setting, but in most cases heating or cooling isn’t being generated. The ‘Auto’ setting, on the other hand, will start the fan over a heating or cooling cycle and shut it off after the cycle is over.

There are benefits and drawbacks to trying the fan setting on your thermostat, and what’s ideal {will|can|should]] depend on your unique comfort requirements.

Advantages to trying the Fan/On setting:

  • You can keep the temperature in each room more consistent by permitting the fan to keep generating airflow.
  • Indoor air quality should improve since constant airflow will keep passing airborne contaminants through the air filter.
  • A smaller number of start-stop cycles for the HVAC fan helps extend its life span. As the air handler is typically connected to the furnace, this means you might prevent the need for furnace repair.

Drawbacks to switching to the Fan/On setting:

  • A constant fan could raise your energy bills slightly.
  • Nonstop airflow may 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 will sometimes persist in unfinished spaces like the attic or an attached garage. If you use the fan setting, your HVAC system can draw this warm air into the rest of your home, forcing the HVAC system to work more to keep up with the preferred temperature. In extreme heat, this could result in needing AC repair more regularly 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. Leaving the fan setting on could draw more cold air upward, increasing the amount of heating you need to remain 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 are different. Leaving the HVAC system’s fan on may be ideal for you if:

Someone in your household has allergies. Allergies and similar 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. Lots of homes deal with difficult hot and cold spots that quickly evolve to a temperature different from the rest of the house. The fan setting should help limit these changes by steadily refreshing each room’s supply of air.