Seasonal Guide: Should My Thermostat Be on Fan or Auto?

When the weather starts to cool off, you are probably wondering about how you’ll prepare your heating and cooling. After all, HVAC costs can make up a large piece of your monthly electric bill. To figure out new ways to reduce costs, some owners take a closer look at their thermostat. Maybe there’s a setting they should use to boost efficiency?

The bulk of thermostats include both a ‘Fan’ or ‘Fan On’ setting. But if the fan is running during a typical cycle, what can the fan setting offer for your HVAC system? This guide can help. We’ll walk through just what the fan setting is and when you can use it to cut costs over the summer or winter.

How Do I Access the Fan Setting on My Thermostat?

For most thermostats, the fan setting indicates that the air handler’s blower fan stays on. Certain furnaces will operate 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 when the cycle is over.

There are pros and cons to trying the fan setting on your thermostat, and whether you do or don’t {will|can|should]] depend on your distinct comfort needs.

Advantages to trying the Fan/On setting:

• You can keep the temperature in every room more balanced by enabling the fan to keep running.
• Indoor air quality will be highest since constant airflow will keep moving airborne pollutants into the air filter.
• Fewer start-stop cycles for the HVAC fan helps expand its life span. As the air handler is typically a component of the furnace, this means you can prevent the need for furnace repair.

Disadvantages to utilizing the Fan/On setting:

• A nonstop fan will likely raise your energy bills slightly.
• Continuous airflow can clog your air filter in a shorter amount of time, increasing the frequency you will want to replace it.

Which Setting for My Thermostat? Fan or Auto in Summer/Winter

Through the summer, warm air can stick around in unfinished spaces such as the attic or an attached garage. If you use the fan setting, your HVAC system may gradually move this warm air into the rest of your home, pushing the HVAC system to work harder to preserve the preferred temperature. In serious heat, this may lead to needing AC repair more regularly as wear and tear grows.

The reverse can happen during 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 could pump more cold air upward, increasing the amount of heating you need to remain warm.

If you’re still trying to determine if you should use the fan/on setting, remember that every home and family’s comfort needs are not the same. Leaving the HVAC system’s fan on may work for you if:

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

Your home has hot and cold spots. All kinds of homes deal with persistent hot and cold spots that quickly evolve to a temperature different from the rest of the house. The fan setting might help lessen these changes by steadily refreshing each room’s airflow.