A ceiling fan is a great way to cool down and save money during the summer, but they have a dirty little secret and we're not talking about that dust you let it collect.

Here's the thing: fans only "work" if you are in the room. A fan does a great job of cooling you off by creating a breeze on your skin (this can work for pets as well). The warmer air is whisked away and your body has an easier time staying cooler.

However, most people turn on fans assuming the circulation will somehow lower the temp in the room. We assume that because when we are in there, that's how it feels. But the actual temp doesn't really change that much.

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In fact, that motor in the fan is creating new heat — like a little space heater. So if you turn it on and leave the room, it's not really helping you, and it's creating heat.

There are some cases where a fan can circulate cooler air below and mix with hot air above, but that only works if you have really poor insulation in your attic.

Now, if you use them correctly, they can and do work to cool you down and save money. But you have to take that extra step of raising your thermostat a few degrees. One study suggests that you can save 16% in cooling costs by using your fan correctly and increasing the temperatures on your thermostat.

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