Once the weather starts to cool off, you might be thinking about how you’ll take full advantage of your heating and cooling. After all, HVAC bills can make up a big chunk of your monthly electric bill. To try and find ways to lower their HVAC bill, some people take a closer look at their thermostat. Maybe there’s a setting they could use to boost efficiency?

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

What Is the Fan Setting on My Thermostat?

For most thermostats, the fan setting means that the HVAC blower fan keeps running. Certain furnaces can operate at a low level in this setting, but in general heating or cooling isn’t being produced. The ‘Auto’ setting, in contrast, will run the fan during a heating or cooling cycle and turn it off after the cycle is finished.

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

Advantages to switching to the Fan/On setting:

• You can keep the temperature in every room more balanced by enabling the fan to keep circulating air.
• Indoor air quality should improve as continuous airflow will keep moving airborne contaminants into the air filter.
• A smaller number of start-stop cycles for the system's fan helps lengthen its life span. Since the air handler is often connected to the furnace, this means you can prevent the need for furnace repair.

Downsides to switching to the Fan/On setting:

• A constant fan could increase your energy costs somewhat.
• Nonstop airflow could 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 use the fan setting, your HVAC system can gradually move this warm air into the rest of your home, pushing the HVAC system to work more to maintain the preferred temperature. In extreme heat, this can result in needing AC repair more regularly as wear and tear grows.

The opposite can happen over the winter. Cooler spaces like a basement will hold onto cooler air, which will eventually drift into the rest of your home. Leaving the fan running could draw more cold air upward, increasing the amount of heating you need to stay warm.

If you’re still trying to figure out if you should switch to the fan/on setting, remember that every home and family’s comfort needs will vary. Leaving the HVAC system’s fan on could be ideal 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 enhance indoor air quality, helping your family breathe easier.

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