When the weather is cooling off, you may be thinking about how you’ll make the most of your heating and cooling. After all, HVAC expenses frequently add up to a significant portion of your monthly electric bill. To try and find ways to save, some homeowners look closely at their thermostat. Could there be a setting they can use to boost efficiency?

The bulk of thermostats have a ‘Fan’ or ‘Fan On’ setting. But if the fan is on during a normal cycle, what will the fan setting offer for an HVAC system? This guide will help. We’ll review just what the fan setting is and how you can use it to save money over the summer or winter.

What Is the Fan Setting on My Thermostat?

For the majority of thermostats, the fan setting signifies that the system's blower fan remains on. Some furnaces will operate at a low level in this setting, but in most cases heating or cooling isn’t being produced. The ‘Auto’ setting, in contrast, will start the fan during a heating or cooling cycle and turn it off once the cycle is over.

There are advantages and disadvantages to trying the fan setting on your thermostat, and whether you do or don’t {will|can|should]] depend on your unique comfort needs.

Advantages to using the Fan/On setting:

  • You can keep the temperature in each room more consistent by enabling the fan to keep generating airflow.
  • Indoor air quality will be highest since continuous airflow will keep forcing airborne contaminants into the air filter.
  • Fewer start-stop cycles for the blower fan helps lengthen its life span. Since the air handler is typically a component of the furnace, this means you might minimize the risk of needing furnace repair.

Disadvantages to switching to the Fan/On setting:

  • A nonstop fan could add to your energy bills somewhat.
  • Constant airflow may clog your air filter soon, 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 will sometimes persist in unfinished spaces including the attic or an attached garage. If you use the fan setting, your HVAC system may draw this warm air into the rest of your home, compelling the HVAC system to work more to maintain the set temperature. In extreme heat, this can result in needing AC repair more often as wear and tear gets worse.

The reverse can happen during 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 could draw more cold air upward, increasing the amount of heating you need to remain warm.

If you’re still trying to decide if you should use the fan/on setting, don’t forget 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 suffers from allergies. Allergies and similar respiratory conditions can be stressful on the family. Leaving the fan on should help to increase indoor air quality, helping your family breathe easier.

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