When the weather is cooling off, you might be concerned about how you’ll prepare your heating and cooling. After all, HVAC costs routinely contribute a significant piece of your monthly electric bill. To figure out new ways to save, some owners look closer at their thermostat. Is there a setting they could use to increase efficiency?

Most thermostats include both a ‘Fan’ or ‘Fan On’ setting. But if the fan is running during a normal cycle, what does the fan setting offer for your HVAC system? This guide should help. We’ll walk through just what the fan setting is and whether you can use it to reduce costs during the summer or winter.

How Do I Access the Fan Setting on My Thermostat?

For the bulk of thermostats, the fan setting means that the air handler’s blower fan stays on. Certain furnaces will generate heat at a low level in this setting, but in most cases heating or cooling isn’t being made. The ‘Auto’ setting, in contrast, will start the fan over a heating or cooling cycle and switch it off once the cycle is complete.

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

Advantages to using the Fan/On setting:

  • You can keep the temperature throughout your home more balanced by permitting the fan to keep generating airflow.
  • Indoor air quality will be highest because steady airflow will keep passing airborne contaminants through the air filter.
  • A smaller amount of start-stop cycles for the system's fan helps expand its life span. As the air handler is often a component of the furnace, this means you might prevent the need for furnace repair.

Disadvantages to using the Fan/On setting:

  • A continuous fan can increase your energy bills somewhat.
  • Continuous airflow could clog your air filter soon, increasing the frequency you will want to replace it.

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

Through the summer, warm air may persist in unfinished spaces including the attic or an attached garage. If you leave the fan on, your HVAC system may gradually move this warm air into the rest of your home, pushing the HVAC system to work more to maintain the preferred temperature. In severe heat, this could result in needing AC repair more often as wear and tear gets worse.

The reverse can take place in the winter. Cooler spaces such as a basement will hold onto cooler air, which may eventually make its way 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 keep warm.

If you’re still trying to figure out if you should use the fan/on setting, don’t forget that every home and family’s comfort needs are different. Leaving the HVAC system’s fan on might be best for you if:

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

Your home has hot and cold spots. Many homes deal with difficult hot and cold spots that quickly return 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.