Message text written by Joe Curry
>Fan rotation may be changed by one of two methods (depending on the
particular fan.
1. Since DC fans run in the direction of the current flow, reversing the
wiring will change the direction of rotation.
2. Some (if not most) of these fans have a reversible blade assembly that
can be removed and turned around to change a "sucker" to a "blower". Check
the fan's instruction sheet for notes on this possibility.
That's my story and I'm stickin'' to it!!!
<
Well, Joe, stick this!
1) True. At least for permanent magnet motors which virtually all fan
motors are.
2) Removing the fan blades and reinstalling them the other way around will
not reverse air flow. However, fan blades are optimized for a particular
direction and will perform poorly when run in the other direction. If you
look at a fan blade from the side you will see that it is not straight. It
starts out fairly flat (where it grabs the air) and becomes increasingly
sharp toward the end where it "flings" the air in the direction of air
flow. When you reverse the rotation (by swapping the leads) it will not
move as much air but by reversing the fan blades you restore the optimized
rotation of the blades.
So, what you meant to say is that to reverse fan rotation you must do 1.
AND 2. , right?
Dave
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