When the weather starts to cool off, you may be concerned about how you’ll take full advantage of your heating and cooling. After all, HVAC bills can make up a significant chunk of your monthly electric bill. To learn new ways to save, some homeowners look closer at their thermostat. Maybe there’s a setting they should use to increase efficiency?

The majority of thermostats include both a ‘Fan’ or ‘Fan On’ setting. But if the fan is on during a normal cycle, what can the fan setting offer for an HVAC system? This guide will help. We’ll share what exactly the fan setting is and how you can use it to cut costs in the summer or winter.

What Is the Fan Setting on My Thermostat?

For most thermostats, the fan setting indicates that the HVAC blower fan keeps running. Some furnaces can operate at a low level in this setting, but for the most part heating or cooling isn’t being made. The ‘Auto’ setting, in contrast, will start the fan during a heating or cooling cycle and switch it off when the cycle is complete.

There are pros and cons 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 throughout your home more consistent by enabling the fan to keep generating airflow.
  • Indoor air quality will be highest because constant airflow will keep moving airborne particles through the air filter.
  • Fewer start-stop cycles for the system's fan helps extend its life span. As the air handler is often part of the furnace, this means you can minimize the risk of needing furnace repair.

Downsides to using the Fan/On setting:

  • A nonstop fan could raise your energy bills by a small margin.
  • Constant airflow could clog your air filter up more quickly, increasing the frequency you should replace it.

{Choosing Between|Should My Thermostat Be on|Which Setting for My Thermostat? Fan or Auto in Summer/Winter

Through the summer, warm air can persist in unfinished spaces like the attic or an attached garage. If you use the fan setting, your HVAC system may pull this warm air into the rest of your home, pushing the HVAC system to work harder to preserve the set temperature. In serious heat, this can result in needing AC repair more regularly as wear and tear increases.

The opposite can take place over the winter. Cooler spaces like a basement will hold onto cooler air, which will eventually make its way into the rest of your home. Keeping the fan on will sometimes pull 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 could work for you if:

Someone in your household suffers from allergies. Allergies and similar respiratory conditions can be stressful on the family. Leaving the fan on is more likely to improve indoor air quality, helping your family breathe easier.

Your home experiences hot and cold spots. Many homes deal with difficult 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 supply of air.