Once the weather starts to cool off, you might be thinking about how you’ll prepare your heating and cooling. After all, HVAC bills can make up a large chunk of your monthly electric bill. To figure out new ways to save, some homeowners look closer at their thermostat. Maybe there’s a setting they can use to increase efficiency?

Most thermostats come with a ‘Fan’ or ‘Fan On’ setting. But if the fan is going during a typical cycle, what can the fan setting offer for an HVAC system? This guide will help. We’ll walk through just 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 bulk of thermostats, the fan setting signifies that the system's blower fan keeps running. Certain furnaces can generate heat at a low level in this setting, but in most cases heating or cooling isn’t being made. The ‘Auto’ setting, in contrast, will run the fan through a heating or cooling cycle and turn it off once the cycle is over.

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

Advantages to utilizing the Fan/On setting:

  • You can keep the temperature throughout your home more consistent by permitting the fan to keep generating airflow.
  • Indoor air quality can increase because steady airflow will keep forcing airborne pollutants through the air filter.
  • A smaller number of start-stop cycles for the HVAC fan helps lengthen its life span. As the air handler is typically part of the furnace, this means you might minimize the risk of needing furnace repair.

Drawbacks to using the Fan/On setting:

  • A nonstop fan could raise your energy expenses somewhat.
  • Continuous airflow can clog your air filter soon, increasing the frequency you’ll need to replace it.

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

Through the summer, warm air will sometimes persist in unfinished spaces like the attic or an attached garage. If you keep the fan running, your HVAC system may pull this warm air into the rest of your home, compelling the HVAC system to work harder to keep up with the desired temperature. In severe heat, this can lead to needing AC repair more quickly as wear and tear gets worse.

The opposite can take place over the winter. Cooler spaces like a basement will hold onto cooler air, which may eventually drift into the rest of your home. Keeping the fan on could pull more cold air upward, increasing the amount of heating you need to stay warm.

If you’re still trying to determine if you should try 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 be ideal for you if:

Someone in your household suffers from allergies. Allergies and similar respiratory conditions can be hard on the family. Leaving the fan on should help to enhance indoor air quality, helping your family breathe easier.

Your home has hot and cold spots. Many homes deal with difficult hot and cold spots that quickly shift 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.