Ceiling fan blade pitch

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  #1  
Old 08-08-05, 08:10 PM
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Ceiling fan blade pitch

I'd like to replace a pair of ceiling fans in my great room. There's been much written about the perfect blade pitch or angle. I've read that 12 is the best pitch for circulation, but then why do some manufacturers tout their 14, or 16?

Any input would be welcome.
 
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Old 08-09-05, 02:44 PM
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Blade pitch is only one variable; it needs to factor nicely with number, shape, sweep, and motor speed *and* motor horsepower... then we can say if the fan is truly efficient. A really good blade will not even have a definable "pitch" - because it won't be flat or simply twisted.

The quietest fans have a large blade surface set at a very aggressive angle, so they can turn slowly without vibration, while moving the same air volume as a faster fan without alot of turbulence. It costs no different to set the blades at 10, 16, or 45 degrees. The cost is in the motor.

Fast little motors are cheaper to manufacture and cost less to run. You can plop one of these in a shallow pitched, lightweight fan without fear of it burning out. You can score the same CFM as the heavier (large ponderous bite) fans at less cost.

In either case the first engineering challenge is in keeping the fan from biting air so quickly the motor overloads. Then, assuming all components fit well together, the "best" open air fan, at a given CFM or horsepower, will be the *slower* one - because it's quieter.

Because the engineering starts at the motor, I would start there in choosing a fan. A higher watt rating roughly translates into work done by the fan. A heavier motor is better too.
 
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Old 08-09-05, 07:22 PM
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Talking Thanks so much

What a wealth of information. Thank you so much.
Now, at least I have a place to start from. And a way to cull the best from so many different ones.
 
 

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