Originally Posted by Retired_AF
Before doing this, make sure the motors can handle the reduced voltage. I'm not sure about power heads, but we some cooling fans installed in the equipment racks at work and one of the guys tried that when they started blowing dust everywhere. The fan motors burned up overnight. I'm not saying not to do it, but just be sure your motors can handle it before you do.
Yeah I would have never done that... (more than 1 fan to a dimmer)
Actually I got the idea from a ceiling fan, and The only reason why I suggested the dimmer is because I have tried it before (it doesn't look good but works) and because those power heads work at 110 V which is the same as a regular light (or at least in the US they both do) so even if you use the maximum brightness/speed the maximum voltage would be 110 V. There is a certain range in which they won't work (not enough current) but it won't damage the motor.
But yeah just make sure that the motor can handle it, you can never be to cautious.