When the weather starts to cool off, you are probably thinking about how you’ll make the most of your heating and cooling. After all, HVAC bills can contribute a significant chunk of your monthly electric bill. To try and find ways to reduce costs, some people look closer at their thermostat. Is there a setting they could use to boost efficiency?

Most thermostats include both a ‘Fan’ or ‘Fan On’ setting. But if the fan is running during a regular cycle, what does the fan setting provide for an HVAC system? This guide should help. We’ll review precisely what the fan setting is and how you can use it to cut 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 keeps running. A few furnaces may continue to operate at a low level in this setting, but in most cases heating or cooling isn’t being generated. The ‘Auto’ setting, conversely, will start the fan during a heating or cooling cycle and shut it off once the cycle is over.

There are benefits and drawbacks to using the fan setting on your thermostat, and what's ideal {will|can|should]] depend on your distinct comfort needs.

Advantages to using the Fan/On setting:

  • You can keep the temperature in every room more uniform by enabling the fan to keep generating airflow.
  • Indoor air quality will be highest as constant airflow will keep forcing airborne contaminants through the air filter.
  • Fewer start-stop cycles for the blower fan helps extend its life span. Because the air handler is typically a component of the furnace, this means you can minimize the risk of needing furnace repair.

Drawbacks to switching to the Fan/On setting:

  • A continuous fan can increase your energy expenses by a small margin.
  • Constant airflow can clog your air filter up more quickly, increasing the frequency you should replace it.

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

During the summer, warm air may linger in unfinished spaces including the attic or an attached garage. If you use the fan setting, your HVAC system might draw this warm air into the rest of your home, forcing the HVAC system to work more to preserve the set temperature. In serious heat, this can result in needing AC repair more regularly as wear and tear grows.

The reverse can take place over the winter. Cooler spaces like a basement will hold onto cooler air, which can 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 keep 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 has allergies. Allergies and similar respiratory conditions can be stressful on the family. Leaving the fan on should help to enhance indoor air quality, helping your family breathe easier.

Your home deals with hot and cold spots. Lots of homes wrestle with stubborn hot and cold spots that quickly evolve to a temperature different from the rest of the house. The fan setting might help limit these changes by consistently refreshing each room’s ventilation.