On or Auto? Which Setting is Best for Your Thermostat Fan?While you may be used to setting your thermostat from heating to cooling mode and back again as the seasons change, you may or may not have paid much attention to the thermostat fan controls. “On” and “auto” may be easy to understand – on means the fan is always on, regardless of whether or not the system is heating or cooling, and auto means that the fan only runs when the furnace, heat pump, or air conditioner tells it to. But understanding which is the better option can be a bit trickier. Here’s how to decide.

Keeping the Fan On

If you have a whole-house humidifier, a central air cleaner, or other systems built into your ductwork to manage indoor air quality, keeping your thermostat fan on means that you’ll always be reaping the benefits those units can offer you. It also means that heat is kept more constant throughout your home as air continually circulates.

On the other hand, it can mean constant fan noise coming through your vents. In the winter, the moving air will add a wind chill effect inside when your heating system isn’t on, which can make you less comfortable. And running the fan at all hours can be a significant energy drain, which you’ll feel on your energy bill.

Setting the Fan to Auto

When your fan is on automatic, it’ll only run when it needs to deliver heated or cooled air, which won’t waste energy. Your HVAC air filters will also last longer because they’re not constantly performing filtration – though that also means that you’re not getting as much air filtration as you could be.

On the other hand, central air cleaners and other units won’t be serving you as well, and you may have less even heat distribution. The fan will stop circulating air whenever the space near the thermostat sensor is satisfied, without regard to other areas of your home.

To learn more about how best to set your thermostat fan, contact us at Wolff Mechanical!

Our goal is to help educate our customers in the Phoenix Valley area of Arizona about energy and home comfort issues (specific to HVAC systems). 

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