Geothermal Fan Mode On vs Auto

When choosing between the “on” and “auto” settings for your geothermal unit’s fan, you can consider things like energy efficiency, air circulation, and comfort:

Energy efficiency

“Auto” is more energy efficient because the fan only runs when the system is heating or cooling, while “on” keeps the fan running continuously. “On” can also lead to higher energy bills, especially if you have a PSC motor that runs at full speed all the time. “Auto” can also help your air filters last longer because they don’t clog as often.

Air circulation

“On” can help air flow more evenly throughout your home and eliminate hot or cold spots. It can also be helpful in extreme heat to regulate the temperature and reduce the amount your AC unit has to work.

Comfort

Some say you can balance comfort and energy efficiency by setting the fan to “auto” when you’re not home and “on” when you’re home. Others say that “auto” can sometimes cause uncomfortable temperature differences between rooms and higher humidity levels.