But why even have something like this at all if it’s not going to move much air?Īllison A. If you don’t like the looks of a ceiling fan, that’s fine. Oh, and that fan with the nesting blades is a ridiculous idea because it has two problems: The blades have to be short to be able to nest together on top of the motor, and the blades are designed for nesting, not moving air. But you can certainly use more energy and make your home warmer by using one. So relax! You won’t get your head chopped off by a (normal) ceiling fan. And it can certainly happen, as you’ll see in the video below…but only if you replace the motor with a more powerful one (like a lawn mower motor) and change out the ceiling fan paddles with razor-sharp blades. Apparently some people worry about getting their heads chopped off by a ceiling fan. I didn’t even know there was a myth about this until I saw the Myth Busters video below. Here in the Southeast, that’s usually in the spring and fall because of the humidity thing we’ve got here. Better yet, use the fans instead of air conditioning when you can. I do it in my house but FSEC found that most people don’t. In short, for ceiling fans to save you money on your energy bills, you have to set the thermostat to a higher temperature. They found that even though the fans ran more than half the day in the test homes, they saw no difference in thermostat setpoints in homes with ceiling fans compared to homes without. In 1996, the Florida Solar Energy Center (FSEC) did a study of homes with ceiling fans. The hypothesis is that people will raise the AC thermostat setting if they’re feeling the breeze of the ceiling fan, but the data don’t support it.
#Ceiling fan clockwise skin
That air moving over your skin still feels good, and so does the low temperature, low humidity air produced by the air conditioner. Once you have a house with air conditioning, though, the dynamics change. You get to keep cool for a relatively low cost. If you don’t have air conditioning at all, having some kind of fans can preserve your sanity. Martin Holladay covered this in his ceiling fan article from 2010, but it’s worth reviewing. Ceiling fans probably won’t save you any money if you have air conditioning That’s why the Big Ass Fans company was originally called the HVLS Fan Company. The only logical conclusion here is to get the biggest fan you can fit into the room, leaving proper clearances, and run it on the lowest speed that keeps you comfortable. Lower speeds are more efficientĪnother thing you’ll notice when looking at fan efficacy labels is that you’ll get more cfm per watt when you run the fan on medium than on high and more still on low than on medium. If you just want cute, though, go right ahead. And it’s why you’ll want to avoid the little short-blade fans like the one above, no matter how cute, if you’re interested in air flow. That’s why the company Big Ass Fans makes big ass fans. The fans with the longest blades have the highest efficacies and those with the shortest blades have the lowest. While you’re checking those labels, you may notice a correlation. Next time you’re looking for a ceiling fan, check the label. A good fan will give you more than 100 cfm per watt a poor one might be as low as 30 cfm per watt.
Its units are cubic feet per minute (cfm) of air flow per watt (W) of electrical power. ( Efficacy is an efficiency rating where the output and input quantities have different units.) For fans, the measure of efficacy is how much air flow you get for the amount of electrical energy you put in. A fan’s efficacy tells you how well it moves airĮvery new ceiling fan being sold in the US these days is labeled with its efficacy. If the air movement created by a ceiling fan isn’t hitting anyone’s skin, it’s just making the space warmer with no cooling benefit. They cool our bodies two ways: by aiding evaporative cooling and by aiding convective cooling. Ĭeiling fans are useful for cooling only when they move air over skin. No, it’s not a lot of heat, but just be aware that the net result of running a ceiling fan is that you’re adding heat to the room, not cooling it. From the second law of thermodynamics, we know where that heat is going - into the cooler room. The infrared image below shows a ceiling fan motor that’s hotter than the room it’s in. Why? Because electric motors are devices that turn electrical energy into mechanical energy, most of which ends up as heat.
(See number 2 below.) But its effect on the room it’s in is to add heat. Sounds clever, but it’s a ridiculous idea.Īnyway, here are seven things about ceiling fans that a lot of people seem not to know. What got me on to this topic was a video of a fan with blades that hide on top of the fan when the fan is turned off.
So why don’t we chop down some myths and misconceptions about ceiling fans. Here we are in the middle of air conditioning season.
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