About "Ask the Energy Expert"
Craig Muccio runs FPL's Conservation Research & Development Program and crunches the numbers to figure out how you can save by managing your energy use.
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Asked on: August 28, 2014 by Beverly H., Weston
Which A/C fan setting costs more, “on” or “auto?” My friend believes the “auto” setting uses more electricity.
That’s actually a common, but important question. The on/auto fan switch on your A/C thermostat will affect the price you pay to cool your home. The A/C fan circulates the cooled or heated air throughout your home. Setting the fan switch to “on” will make the A/C fan run continuously, 24 hours a day. Choosing the “auto” setting will cause the fan to shut off with the rest of the cooling system as soon as your desired temperature on your thermostat is reached.
Fan “on” costs more
Advice from friends can be helpful, but in this case your friend was mistaken to think that the auto setting used more electricity. Let’s assume your air conditioner normally cycles off 30 percent of the time. In this example, turning the fan switch to “on” will make the fan run over 200 extra hours a month. For a typical size central air conditioner, that would cost you about $8 more each month. Keep in mind, a fan that runs all the time may also wear out sooner.
Another reason to keep it on “auto”
Setting your A/C fan to auto also helps provide better dehumidification. Have you noticed how moisture from the air condenses on the outside of a cold drink on a humid day? Your A/C unit captures moisture the same way, helping your home feel more comfortable. When the fan cycles off using the auto mode, moisture has a chance to drip from the cold cooling coils into the condensation pan and then drain outside. However, when the fan runs all the time in the “on” setting, less moisture has a chance to drip and drain outside. Instead, some gets blown back into the air again.
Some people prefer the feel or sound of the fan running all the time. If that’s you, at least now you know how much that choice will cost you.
Learn how to save even more
During Florida’s hottest months, we want to remind you that you can save five percent on your monthly cooling costs for each degree you turn your thermostat up. Also, our top summer tips can help you save even more.
You can also take our Online Home Energy Survey to get a personalized savings plan filled with energy-saving tips and recommendations. It’s easy, and can save you up to $250 a year.
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