As the weather starts to cool off, you may be wondering about how you’ll make the most of your heating and cooling. After all, HVAC costs routinely add up to a significant piece of your monthly electric bill. To try and find ways to lower their HVAC bill, some people look closer at their thermostat. Maybe there’s a setting they can use to boost efficiency?

Most thermostats come with a ‘Fan’ or ‘Fan On’ setting. But if the fan is running during a normal cycle, what will the fan setting offer for your HVAC system? This guide will help. We’ll review just what the fan setting is and when 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 indicates that the HVAC blower fan keeps running. Certain furnaces will operate at a low level with this setting, but in general heating or cooling isn’t being made. The ‘Auto’ setting, in contrast, will start the fan through a heating or cooling cycle and switch it off once the cycle is over.

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

Advantages to utilizing the Fan/On setting:

  • You can keep the temperature throughout your home more balanced by allowing the fan to keep running.
  • Indoor air quality can increase since steady airflow will keep forcing airborne pollutants into the air filter.
  • A smaller number of start-stop cycles for the system's fan helps lengthen its life span. As the air handler is usually connected to the furnace, this means you might avoid needing furnace repair.

Disadvantages to using the Fan/On setting:

  • A nonstop fan could add to your energy bills somewhat.
  • Continuous airflow could clog your air filter soon, increasing the frequency you should replace it.

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

In the summer, warm air will sometimes persist in unfinished spaces such as the attic or an attached garage. If you use the fan setting, your HVAC system can draw this warm air into the rest of your home, compelling the HVAC system to run longer to maintain the set temperature. In extreme heat, this could lead to needing AC repair more quickly as wear and tear increases.

The reverse can occur over the winter. Cooler spaces like a basement will hold onto cooler air, which will eventually flow into the rest of your home. Keeping the fan on could pump more cold air upward, increasing the amount of heating you need to stay 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 tough on the family. Leaving the fan on is more likely to improve indoor air quality, helping your family breathe easier.

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