When you consider ceiling fans, your mind isn’t typically drawn to the science behind how they work. They are just a fan that hangs from the ceiling that blows air down on you to keep you cool. Well, things aren’t always that simple.
My wife and I are one of those couples who sleep with a ceiling fan running. We do this year-round. We like the air moving and also the small amount of white noise created by the motor and air movement. A few days ago, the ceiling fan in our bedroom started making a sort of squeeky click at a regular rhythm. This does not make a good companion sound for sleeping. So, we went to our local big-box hardware store and bought a new fan.
This new fan is 52” and has seven blades. That’s right, seven blades. It is rated as one of the top air-movers. (Air movement for ceiling fans is measured in CFM, or cubic feet per minute)
We brought the fan home and I installed it. I’ve installed many ceiling fans in my life and I will say that they have become much easier over the years. This one even included a nice quick-connect for the wiring which was very nice.
Once it was installed, I tested it to be sure I hadn’t wired it wrong. We certainly don’t want sparks or flames. After everything was thoroughly tested, we went to bed.
We discovered that our fancy new fan did not keep us cool. In fact, we couldn’t feel any air moving at all. This was in spite of the fact that it looked like the propeller on the front of a Sopwith Camel biplane. It was a blur of movement and you could hear the air whooshing above.
So, I started troubleshooting. Why wasn’t the fan moving air. I thought perhaps I had switched it to reverse, which pulls air up instead of pushing it down. Nope. My troubleshooting ended there. As I said in the first part of this article, its just a fan. Not much science there, right?
We thought about packing the fan up and returning it to the big-box store. Maybe a different model would work better. After all, the one we had before had done a good job of moving air, and it probably had a lower CFM than this new one. The new one had to be defective, right?
Prepare yourself for some simple science related to ceiling fans.
The ceiling in my bedroom is trayed. That means that it has tiers the are gradually taller as you get closer to the middle of the room. It is purely decorative and gives the room the appearance of being bigger. The new ceiling fan came with what I would call a “stubby” down rod. (The down rod is the metal pipe that connects the ceiling fan motor to the mount on the ceiling) We thought it would look sleeker to have the ceiling fan recessed in the upper-most tray of the ceiling.
As it turns out, this wasn’t a good idea. Ceiling fans require a certain amount of free space around them from which to pull air. Since our fan was up against the ceiling and the sides of the “tray” were fairly close to the end of the fan blades, the fan couldn’t “breathe.” It was basically just stirring the air around up in the trayed ceiling. No air was moving down.
To remedy this situation, I bought a 12” down rod from the same big-box store we purchased the fan from. This was a whopping $7.00.
The down rod was a relatively easy install. The downside was that I had to take all of the fan blades off again before taking the ceiling fan down to install the new down rod.
After installing the new down rod, I went to the wall switch and held my breath.
Switch on. Fan moving.
I could now feel the wonderful breeze from the fan! In fact, it was really moving the air! Success!
So, now you and I know more about ceiling fans than I would have thought necessary. They’ve got to have room to breathe!
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