Seasonal Settings: Should My Thermostat Be Set to Fan or Auto?

When the weather is cooling off, you might be wondering about how you’ll prepare your heating and cooling. After all, HVAC bills frequently make up a large piece of your monthly electric bill. To try and find ways to save, some owners look closer at their thermostat. Is there a setting they could use to improve efficiency?

The majority of thermostats come with a ‘Fan’ or ‘Fan On’ setting. But if the fan is going during a regular cycle, what can the fan setting provide for the HVAC system? This guide can help. We’ll review what exactly the fan setting is and when you can use it to cut costs during the summer or winter.

Should I Use My Thermostat's Fan Setting?

For the majority of thermostats, the fan setting indicates that the HVAC blower fan stays on. Some furnaces may continue to generate heat at a low level with this setting, but in general 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 after the cycle is finished.

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

Advantages to trying the Fan/On setting:

• You can keep the temperature throughout your home more consistent by allowing the fan to keep running.

• Indoor air quality should improve because steady airflow will keep moving airborne particles through the air filter.

• A smaller amount of start-stop cycles for the system's fan helps expand its life span. As the air handler is often part of the furnace, this means you might prevent the need for furnace repair.

Drawbacks to switching to the Fan/On setting:

• A constant fan will likely raise your energy costs by a small margin.

• Nonstop airflow can clog your air filter soon, 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 will sometimes persist in unfinished spaces like the attic or an attached garage. If you use the fan setting, your HVAC system might draw this warm air into the rest of your home, pushing the HVAC system to work harder to maintain the preferred temperature. In severe heat, this can lead to needing AC repair more quickly as wear and tear increases.

The reverse can happen during the winter. Cooler spaces like a basement will hold onto cooler air, which will eventually drift into the rest of your home. Keeping the fan on will sometimes draw more cold air upward, increasing the amount of heating you need to remain warm.

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

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

Your home experiences hot and cold spots. All kinds of homes deal with difficult hot and cold spots that quickly return to a temperature different from the rest of the house. The fan setting can help minimize these changes by consistently refreshing each room’s airflow.