As the weather starts to cool off, you may be concerned about how you’ll prepare your heating and cooling. After all, HVAC bills routinely add up to a significant portion of your monthly electric bill. To figure out new ways to save, some owners take a closer look at their thermostat. Maybe there’s a setting they can use to boost efficiency?

The bulk of thermostats have a ‘Fan’ or ‘Fan On’ setting. But if the fan is on during a typical cycle, what does the fan setting offer for your HVAC system? This guide can help. We’ll walk through what exactly the fan setting is and when you can use it to save money over the summer or winter.

How Do I Access the Fan Setting on My Thermostat?

For most thermostats, the fan setting signifies that the air handler’s blower fan keeps running. A few furnaces will run at a low level in this setting, but in general heating or cooling isn’t being produced. The ‘Auto’ setting, in contrast, will start the fan through a heating or cooling cycle and switch it off after the cycle is complete.

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

Advantages to utilizing the Fan/On setting:

  • You can keep the temperature throughout your home more balanced by enabling the fan to keep generating airflow.
  • Indoor air quality can increase because steady airflow will keep moving airborne pollutants through the air filter.
  • Fewer start-stop cycles for the system’s fan helps lengthen its life span. Because the air handler is often part of the furnace, this means you can prevent the need for furnace repair.

Drawbacks to using the Fan/On setting:

  • A constant fan will likely raise your energy expenses by a small margin.
  • Constant airflow could clog your air filter up more quickly, increasing the frequency you’ll need to replace it.

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

During the summer, warm air may linger in unfinished spaces including the attic or an attached garage. If you keep the fan running, your HVAC system can pull this warm air into the rest of your home, compelling the HVAC system to work harder to preserve the set temperature. In extreme heat, this can lead to needing AC repair more often as wear and tear increases.

The reverse can occur in the winter. Cooler spaces such as a basement will hold onto cooler air, which may eventually drift into the rest of your home. Keeping the fan on could pump more cold air upward, increasing the amount of heating you need to stay warm.

If you’re still trying to determine if you should try the fan/on setting, keep in mind that every home and family’s comfort needs are different. Leaving the HVAC system’s fan on could work for you if:

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

Your home experiences hot and cold spots. Many homes wrestle with persistent hot and cold spots that quickly return to a temperature different from the rest of the house. The fan setting might help limit these changes by steadily refreshing each room’s supply of air.