As the weather starts to cool off, you may be thinking about how you’ll prepare your heating and cooling. After all, HVAC costs frequently add up to a large portion of your monthly electric bill. To figure out new ways to reduce costs, some owners look closely at their thermostat. Maybe there’s a setting they should use to increase efficiency?

Most thermostats have a ‘Fan’ or ‘Fan On’ setting. But if the fan is on during a regular cycle, what can the fan setting offer for an HVAC system? This guide will help. We’ll walk through precisely what the fan setting is and whether you can use it to reduce costs over the summer or winter.

Should I Use My Thermostat's Fan Setting?

For the majority of thermostats, the fan setting means that the system's blower fan remains on. A few furnaces may continue to run at a low level in this setting, but in most cases heating or cooling isn’t being produced. The ‘Auto’ setting, conversely, will run the fan through a heating or cooling cycle and shut it off after the cycle is over.

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

Advantages to using the Fan/On setting:

  • You can keep the temperature throughout your home more balanced by permitting the fan to keep circulating air.
  • Indoor air quality will be highest as continuous airflow will keep passing airborne pollutants through the air filter.
  • A smaller number of start-stop cycles for the system's fan helps extend its life span. Because the air handler is typically part of the furnace, this means you can avoid needing furnace repair.

Downsides to switching to the Fan/On setting:

  • A continuous fan will likely raise your energy expenses slightly.
  • Nonstop airflow can clog your air filter up more quickly, increasing the frequency you should replace it.

{Choosing Between|Should My Thermostat Be on|Which Setting for My Thermostat? Fan or Auto in Summer/Winter

Through the summer, warm air may persist in unfinished spaces like the attic or an attached garage. If you keep the fan running, your HVAC system might draw this warm air into the rest of your home, pushing the HVAC system to work harder to maintain the desired temperature. In severe heat, this may lead to needing AC repair more regularly as wear and tear gets worse.

The reverse can happen over the winter. Cooler spaces like a basement will hold onto cooler air, which may eventually flow into the rest of your home. Keeping the fan on may pump 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 will vary. Leaving the HVAC system’s fan on could be ideal for you if:

Someone in your household deals with allergies. Allergies and other respiratory conditions can be stressful on the family. Leaving the fan on should help to improve indoor air quality, helping your family breathe easier.

Your home experiences hot and cold spots. All kinds of homes deal with persistent hot and cold spots that quickly shift to a temperature different from the rest of the house. The fan setting should help lessen these changes by consistently refreshing each room’s supply of air.