When the weather starts to cool off, you might be thinking about how you’ll prepare your heating and cooling. After all, HVAC bills can make up a large chunk of your monthly electric bill. To figure out new ways to reduce costs, some people look closer at their thermostat. Maybe there’s a setting they should use to improve efficiency?

The bulk of thermostats include both a ‘Fan’ or ‘Fan On’ setting. But if the fan is on during a regular cycle, what can the fan setting provide for the HVAC system? This guide can help. We’ll walk through precisely what the fan setting is and whether you can use it to reduce costs in the summer or winter.

My Thermostat Has a Fan Setting?

For the majority of thermostats, the fan setting signifies that the system's blower fan stays on. Some furnaces can generate heat at a low level with this setting, but for the most part heating or cooling isn’t being generated. The ‘Auto’ setting, conversely, will run 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 unique comfort preferences.

Advantages to switching to the Fan/On setting:

  • You can keep the temperature throughout your home more balanced by enabling the fan to keep running.
  • Indoor air quality will be highest as continuous airflow will keep passing airborne contaminants through the air filter.
  • A smaller amount of start-stop cycles for the blower fan helps lengthen its life span. Because the air handler is often part of the furnace, this means you can minimize the risk of needing furnace repair.

Disadvantages to utilizing the Fan/On setting:

  • A continuous fan will likely add to your energy bills somewhat.
  • Nonstop airflow can clog your air filter up more quickly, 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 Summer/Winter

During the summer, warm air will sometimes linger in unfinished spaces including the attic or an attached garage. If you leave the fan on, your HVAC system may pull this warm air into the rest of your home, forcing the HVAC system to work harder to keep up with the desired temperature. In extreme heat, this could result in needing AC repair more quickly as wear and tear grows.

The reverse can happen over the winter. Cooler spaces like a basement will hold onto cooler air, which may eventually drift into the rest of your home. Leaving the fan setting on will sometimes pull more cold air upward, increasing the amount of heating you need to stay 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 will vary. Leaving the HVAC system’s fan on may be ideal for you if:

Someone in your household suffers from allergies. Allergies and similar respiratory conditions can be tough on the family. Leaving the fan on should help to enhance indoor air quality, helping your family breathe easier.

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