Solved: Should My Thermostat Run on Fan or Auto?

As the weather starts to cool off, you might be wondering about how you’ll take full advantage of your heating and cooling. After all, HVAC costs routinely make up a large piece of your monthly electric bill. To figure out new ways to lower their HVAC bill, some homeowners look closer at their thermostat. Is there a setting they can use to increase efficiency?

The bulk of thermostats include both a ‘Fan’ or ‘Fan On’ setting. But if the fan is going during a normal cycle, what can the fan setting offer for an HVAC system? This guide can help. We’ll walk through precisely what the fan setting is and whether you can use it to save money over the summer or winter.

My Thermostat Has a Fan Setting?

For the bulk of thermostats, the fan setting signifies that the HVAC blower fan keeps running. Some furnaces will operate at a low level with this setting, but in most cases heating or cooling isn’t being generated. The ‘Auto’ setting, on the other hand, will run the fan through a heating or cooling cycle and shut 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 personal comfort needs.

Advantages to trying the Fan/On setting:

• You can keep the temperature throughout your home more uniform by allowing the fan to keep circulating air.
• Indoor air quality will be highest because continuous airflow will keep moving airborne contaminants into the air filter.
• Fewer start-stop cycles for the HVAC fan helps extend its life span. As the air handler is often part of the furnace, this means you might avoid needing furnace repair.

Disadvantages to utilizing the Fan/On setting:

• A constant fan will likely add to your energy bills slightly.
• Constant airflow can clog your air filter in a shorter amount of time, increasing the frequency you’ll need to replace it.

{Choosing Between|Should My Thermostat Be on|Which Setting for My Thermostat? Fan or Auto in Summer/Winter

During the summer, warm air may persist in unfinished spaces such as 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 run longer to keep up with the preferred temperature. In severe heat, this can result in needing AC repair more quickly as wear and tear gets worse.

The reverse can take place during the winter. Cooler spaces such as a basement will hold onto cooler air, which will eventually make its way into the rest of your home. Leaving the fan running may pull more cold air upward, increasing the amount of heating you need to stay warm.

If you’re still trying to decide if you should use the fan/on setting, keep in mind 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 is more likely to enhance indoor air quality, helping your family breathe easier.

Your home experiences hot and cold spots. Lots of homes wrestle with difficult hot and cold spots that quickly evolve 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.