Heng's vortex 12"
Pulled the trigger on a 12" retrofit fan, the Heng's Vortex III for my kitchen skylight. I've had the 9" vortex II in the bathroom for a few years now and it's proven reliable. $70 shipped, compare...
Forum Discussion
Blacklane wrote:
I was going to install a similar PWM speed controller on a Heng's fan, but discovered (a) it made an loud high-pitched noise whenever the fan was set to any speed other than full, and (b) it drew several milliamps of parasitic current while turned off.
Maybe this controller is better, but those are a couple of things to maybe test before cutting and drilling.
I did install the speed controller on my stove vent and it works great. I installed it down-stream of the existing switch to avoid parasitic current draw.
My parasite draw is around 10amps, so I'm not worried about a few more milliampere :)
The controller I have designed operates at 30khz, well beyond human perception. Most of the cheap units on eBay and Amazon operate at a much lower frequency, because it's a cheaper solution.
