On or Auto: Which is the Better Thermostat Setting for Your Des Moines Home?

June 16, 2016

There are many different thermostats on the market today, and they're all equipped with a control that causes confusion for homeowners - the fan button that comes with two choices, "auto" and "on." To help you decide which thermostat setting is the best one to use, we'll answer some questions about the fan switch itself and how each of its setting choices affects HVAC system operation.

What Does the Fan Button Do? 
The fan switch on your thermostat controls how the blower operates. When it's in the "on" position, the fan operates continuously, even when the cooling coil cycles off. In the "auto" position, the blower cycles on and off in conjunction with the evaporator coil.

How Does the "Auto" Setting Impact HVAC Operation?
If your HVAC system has a single-speed fan, setting the switch to "auto" allows the blower to work in tandem with the cooling components to ensure maximum efficiency. Keeping the fan on "auto" also means air gets drawn through the air filter less often, so it won't need replacement as frequently. One of the negative aspects of not operating the fan continuously is that your home can start to get stuffy and warm when the cooling system isn't running.

How Does the "On" Setting Affect the Cooling System?
If you run the fan non-stop while using your A/C or heat pump, any humid, warm air that builds up in the ductwork during the equipment's off cycles gets distributed throughout your home. This erodes your comfort and increases the cooling equipment's workload and energy consumption. You'll also pay more to run the fan, which uses about as much electricity as a refrigerator. If you want to use the "on" setting for air circulation and filtration, it's wiser to upgrade to a variable-speed blower. With a variable-speed unit, you'll gain better filtration and actually save energy since it runs on low almost non-stop, and ramps up automatically only when extra cooling is needed.

If you have questions about which thermostat setting is best and need expert advice, contact the Des Moines home comfort pros at Lozier Heating & Cooling today. Our goal is to help educate our customers in the greater Des Moines, Iowa area about energy and home comfort issues (specific to HVAC systems). Credit/Copyright Attribution: "doomu/Shutterstock"