When the weather is cooling off, you might be concerned about how you’ll make the most of your heating and cooling. After all, HVAC expenses routinely make up a large portion of your monthly electric bill. To figure out new ways to lower their HVAC bill, some homeowners look closer at their thermostat. Could there be a setting they could use to increase efficiency?

The majority of thermostats have a ‘Fan’ or ‘Fan On’ setting. But if the fan is on during a normal cycle, what can the fan setting offer for your HVAC system? This guide will help. We’ll walk through precisely what the fan setting is and when you can use it to cut costs in the summer or winter.

Should I Use My Thermostat’s Fan Setting?

For the bulk of thermostats, the fan setting means that the system’s blower fan remains on. A few furnaces may continue to generate heat at a low level in this setting, but for the most part heating or cooling isn’t being generated. The ‘Auto’ setting, on the other hand, will turn on the fan through a heating or cooling cycle and shut it off once the cycle is complete.

There are pros and cons to using the fan setting on your thermostat, and whether you do or don’t {will|can|should]] depend on your personal comfort needs.

Advantages to switching to 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 should improve since constant airflow will keep passing airborne contaminants into the air filter.
  • A smaller number of start-stop cycles for the blower fan helps extend its life span. Because the air handler is often a component of the furnace, this means you can minimize the risk of needing furnace repair.

Disadvantages to switching to the Fan/On setting:

  • A constant fan can add to your energy costs somewhat.
  • Continuous airflow can clog your air filter in a shorter amount of time, increasing the frequency you’ll need to replace it.

Should My Thermostat Be on? Fan or Auto in Each Season

In the summer, warm air can linger in unfinished spaces like the attic or an attached garage. If you use the fan setting, your HVAC system can pull this warm air into the rest of your home, compelling the HVAC system to work more to keep up with the set temperature. In serious heat, this may result in needing AC repair more often 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 will eventually make its way into the rest of your home. Leaving the fan setting on may pump more cold air upward, increasing the amount of heating you need to stay warm.

If you’re still trying to decide if you should try the fan/on setting, don’t forget that every home and family’s comfort needs will vary. Leaving the HVAC system’s fan on may be ideal for you if:

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

Your home has hot and cold spots. All kinds of homes wrestle with difficult 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 constantly refreshing each room’s ventilation.