When setting your thermostat, have you ever wondered about the difference between the "On" and "Auto" fan settings? If you fiddled with it, you likely figured it out quickly. What you may not know is why one setting is better than the other when it comes to energy efficiency and home comfort.
"On" vs. "Auto"
First, it's important to recognize that a central forced-air HVAC system has two interlinking modes of operation. The first is the equipment that cools or heats the air. The second is the system that distributes the air throughout the house and draws it back to the equipment to be conditioned again. The thermostat fan setting controls operation of the second part of that equation.When the fan is set to "On," the blower motor and fan run 24/7, regardless of whether the A/C, heat pump or furnace is cooling or heating the air. Setting your thermostat fan setting to "Auto," however, makes sure the fan only operates when the system is actively cooling or heating the air.
Advantages of the "Auto" Setting
Here are a few benefits of keeping your thermostat fan set to "Auto:"
If your central HVAC system is oversized, which is common in residential systems, it will cycle on and off frequently. Residual moisture removed from the air during the cooling process is left on the evaporator coil. If the fan is running continuously, the moving air will re-absorb that moisture and circulate it through the house. Your A/C ends up working harder to dehumidify the air, and the cooled air will feel clammy.
When the fan is running all the time, it uses more energy than it would if it were set to "Auto."
If your ductwork isn't tight, the constant fan operation may result in more air infiltration into the ducts. Depending on the source of that air, it could be dirty or humid if it's entering the ducts from an attached garage or crawl space.
For more help setting your thermostat, please contact us at Air Assurance. We provide quality HVAC services to residents of Broken Arrow.
Our goal is to help educate our customers in the Tulsa and Broken Arrow, Oklahoma area about energy and home comfort issues (specific to HVAC systems). Credit/Copyright Attribution: “Daniel Hodac/Shutterstock”