420 Magazine Background

Variac for inline fan?


Well-Known Member
Hi! I bought a new fan a few weeks ago, Panasonic FV-20NLF1 WhisperLine 240 CFM.
It's very quiet, but I have put a speed controler on it because it blow too much for my little tent! :laugh:
But with it I have the "hum" noise from the fan.

I've read that a Variac would make no noise, but I read elsewhere that it should not be use for a fan!

Does someone actually use a variac with an inline fan here?

I'm looking for this one.


- 20 amp max output
- 2000VA Variable Voltage Regulator
- Input voltage: 110VAC
- Output voltage: 0-130VAC 60Hz
- Analog Output Power Meter Included

Thanks! :)


Well-Known Member
After checking more threads and other forums, I bought the variac this christmas.
I should have get it way earlier, this thing is fabulous!!! It make no sound! I set the voltage to 50v and the only thing I hear is the little wooch from the air, but only if I put my head against the exhaust of the inline fan!
When I close the door of the closet it's perfect! :)


Dwight Monk

420 Support
420 Staff
I think it varies on the Fan/Company and what is in their manual, as one I have very specifically states not to run it with a speed control as it will void the warranty on it if you do. Guys at the Hydro Store I bought it at even asked that question (and some others) of if I was going to vary the speed before they recommended which ones they thought were best for me and the space I was growing in. So must be something in the design or motor where it not made to run at varying speeds.


Well-Known Member
The biggest problem with speed controller (besides the humm noise), is that to slow down a fan it pulsate the power on and off, which is not good for the fan motor. And if set too low, the fan would shot down.

A few weeks before christmas I set it to low, at the time it was ok but after a while the fan stop and when I get back my condo was smelling a lot! :33:

Now with the variac, no more problems with that! :)


Well-Known Member
Sorry I didn't check the forums for a while!
Right now I'm at 39v, and my 2x2x6 tent has a negative pressure! :) But I have only a seed inside! :laugh:
One thing to check is the pre-filter on the scrubber, it should be washed (or changed) each month so the air flow stay good.
Top Bottom