By: Brad Goar
That’s actually a common, but important question. Most people have been told to keep their thermostat set to “auto” instead of “on”. But is there really a difference?
You bet there is. The on/auto fan switch on your A/C thermostat will affect the price you pay to cool your home. And keeping your thermostat set to “on” can actually cost you more money. Before we get into why, we need to explain how they’re different.
What AUTO and ON mean
AUTO means the fan turns on “automatically” during your home’s heating and cooling cycles. Once your home reaches your desired indoor temperature, the system, including the blower fan, shuts off until the next cycle. This is the most energy efficient option.
ON means the fan is constantly running, 24 hours a day, even when your system isn’t working to heat or cool the air. When the thermostat fan is set to on, your fan is always using energy, which will increase your monthly utility bills.
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
Now, for the first time ever, you can know what it really costs to run your A/C, appliances and devices, with the new FPL Energy Manager. Plus, you get personalized tips on how to save on your bill.
Do you have an FPL business account? Now, it’s easier than ever to take control of your energy use and your bill with FPL’s new Business Energy Manager.