When the weather begins to cool off, you may be wondering about how you’ll make the most of your heating and cooling. After all, HVAC costs routinely make up a large chunk of your monthly electric bill. To try and find ways to reduce costs, some people look closer at their thermostat. Maybe there’s 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 typical cycle, what can the fan setting offer for the HVAC system? This guide should help. We’ll review precisely what the fan setting is and how you can use it to reduce costs over the summer or winter.

What Is the Fan Setting on My Thermostat?

For the majority of thermostats, the fan setting signifies that the HVAC blower fan stays on. Certain furnaces may continue to run at a low level with this setting, but for the most part heating or cooling isn’t being generated. The ‘Auto’ setting, in contrast, will run the fan during a heating or cooling cycle and shut it off once the cycle is over.

There are pros and cons to trying the fan setting on your thermostat, and what's ideal {will|can|should]] depend on your unique comfort requirements.

Advantages to trying the Fan/On setting:

  • You can keep the temperature throughout your home more consistent by enabling the fan to keep running.
  • Indoor air quality should improve because continuous airflow will keep moving airborne contaminants into the air filter.
  • A smaller amount of start-stop cycles for the system's fan helps expand its life span. Since the air handler is typically part of the furnace, this means you could minimize the risk of needing furnace repair.

Disadvantages to utilizing the Fan/On setting:

  • A constant fan can increase your energy bills by a small margin.
  • Nonstop airflow can clog your air filter up more quickly, increasing the frequency you will want to replace it.

Should My Thermostat Be on Fan or Auto in Summer/Winter

During the summer, warm air can persist in unfinished spaces such as the attic or an attached garage. If you keep the fan running, your HVAC system may gradually move this warm air into the rest of your home, forcing the HVAC system to work more to maintain the set temperature. In serious heat, this may result in needing AC repair more quickly as wear and tear increases.

The opposite can happen during the winter. Cooler spaces like a basement will hold onto cooler air, which can eventually flow into the rest of your home. Leaving the fan setting on will sometimes draw more cold air upward, increasing the amount of heating you need to keep warm.

If you’re still trying to decide if you should use 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 increase indoor air quality, helping your family breathe easier.

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