Once the weather is cooling off, you may be thinking about how you’ll make the most of your heating and cooling. After all, HVAC costs can make up a big chunk of your monthly electric bill. To figure out new ways to lower their HVAC bill, some owners look closer at their thermostat. Could there be a setting they could use to boost efficiency?

Most thermostats come with a ‘Fan’ or ‘Fan On’ setting. But if the fan is running during a regular cycle, what can the fan setting provide for an HVAC system? This guide can help. We’ll review what exactly the fan setting is and when you can use it to reduce costs in the summer or winter.

Should I Use My Thermostat’s Fan Setting?

For the bulk of thermostats, the fan setting indicates that the system’s blower fan stays on. A few furnaces will run at a low level with this setting, but for the most part heating or cooling isn’t being generated. The ‘Auto’ setting, on the other hand, will turn on the fan over a heating or cooling cycle and turn it off once the cycle is complete.

There are benefits and drawbacks to trying the fan setting on your thermostat, and whether you do or don’t {will|can|should]] depend on your unique comfort requirements.

Advantages to using the Fan/On setting:

  • You can keep the temperature in every room more consistent by allowing the fan to keep circulating air.
  • Indoor air quality will be highest as steady airflow will keep moving 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 usually connected to the furnace, this means you could minimize the risk of needing furnace repair.

Drawbacks to using the Fan/On setting:

  • A nonstop fan could increase your energy expenses by a small margin.
  • Nonstop airflow can clog your air filter soon, increasing the frequency you will want to replace it.

Which Setting for My Thermostat? Fan or Auto in Each Season

In the summer, warm air will sometimes persist in unfinished spaces such as the attic or an attached garage. If you keep the fan running, your HVAC system might gradually move this warm air into the rest of your home, pushing the HVAC system to run longer to preserve the desired temperature. In severe heat, this may result in needing AC repair more quickly as wear and tear grows.

The reverse can occur 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 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 use the fan/on setting, remember that every home and family’s comfort needs are different. Leaving the HVAC system’s fan on could be best 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 improve indoor air quality, helping your family breathe easier.

Your home experiences 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 can help lessen these changes by constantly refreshing each room’s supply of air.