fan speed controller is noisy?

I have a Sunleaves 4" Windtunnel inline fan, and a Speedster fan speed controller. For some reason, when I set the fan speed controller to VAR, the fan emits a buzzing/whirring sound. It does this at all speeds, but is completely absent when I run the fan at FULL. Why is it doing this?? I thought the whole point of a fan speed controller was to make it LESS noisy, not more.

some fans(usually cheaper inline fans) not compatable with variable speed controler such as "Speedster". Had same problem with an Active Air 6" fan.

if it is noise you wish to reduce and not speed of fan , they make noise dampening clamps and mounts for that purpose. Work pretty well allthough its easy to make yourself with old innertubes or such. "CanFan", and "Vortex" fans are compatable with speed controllers.

Well, the Sunleaves fan is certainly not cheap. But anyhow, I solved the problem by buying one of these. It slows the fan down without creating any additional noise. It's bulky and more expensive, but the Speedster is useless, so I'm returning it to the hydro shop.

I apologize. not cheap by any means(hard work coming up with $ as we all know)- but cheaper and less well built as a CanFan or Vortex. Something with the internal components. Transducer or something. More expensive(usually) fans have a transducer on motor that can handle a speed control unit such as Speedster. The motor, bushings, etc. are built to perform at differnt(variable) speeds. Lower budget fans dont perform as well or at all with controller. Vortex and Can Fan build thier own products. Sunleaves just puts their name on products. Dont think they build em. Cheap is the name of that game not high quality. Glad you solved problem.

Vortex & CAP Valueline (CHEAP) fans do not have any compatability issues when running with a speed controller. Just an FIY for anyone worried about this.

iforgotagain said:

[FONT=tahoma,sans-serif]Inline exhaust fans are AC not DC. In order to limit the speed of the fan you need to limit the voltage going to the fan. The speedster controllers (cheaper speed controllers) work by cutting the line voltage really really quickly to limit the voltage going to the fan. So you are running 120V to the fan, but you are stopping any voltage from getting to the fan 10 times every second depending on how you turn the dial (that's a figure I just made up).

The downside to this is that it will cause most fans to hum to some extent depending how many times a second you are cutting the voltage. The slower you want the fan to spin the louder hum you will hear since you are cutting the power to the fan a few times every second/millisecond. Often times, the hum of the fan can be louder than the fan. The quick stopping and starting of the motor can reduce the life of the fan.

Speedster: http://www.horticulturesource.com/product_info.php?products_id=1665

On the other hand, a variac controller actually changes the AC line voltage from 120V to whatever you specify without cutting power to the fan. This removes all hum completely. I purchased this unit for $61 shipped. My current fan is completely silent with the variac.

Variac Autotransformer: http://www.officebeyond.com/va-130-0300.html[/FONT]

Click to expand...

I was going to jump in but your post pretty much said everything needed to say....... I have a nice elicent fan and it hums too with the speedster i just dont worry about because its less noisy then my ballats so who cares really

I use active air fans with this controller: http://http://www.plantlightinghydroponics.com/hydrofarm-variable-speed-fan-control-p-2263.html

I have never had this problem and I use 4 different fans, 6" and 8".

iforgotagain said:

[FONT=tahoma,sans-serif]Inline exhaust fans are AC not DC. In order to limit the speed of the fan you need to limit the voltage going to the fan. The speedster controllers (cheaper speed controllers) work by cutting the line voltage really really quickly to limit the voltage going to the fan. So you are running 120V to the fan, but you are stopping any voltage from getting to the fan 10 times every second depending on how you turn the dial (that's a figure I just made up).

The downside to this is that it will cause most fans to hum to some extent depending how many times a second you are cutting the voltage. The slower you want the fan to spin the louder hum you will hear since you are cutting the power to the fan a few times every second/millisecond. Often times, the hum of the fan can be louder than the fan. The quick stopping and starting of the motor can reduce the life of the fan.

Speedster: http://www.horticulturesource.com/product_info.php?products_id=1665

On the other hand, a variac controller actually changes the AC line voltage from 120V to whatever you specify without cutting power to the fan. This removes all hum completely. I purchased this unit for $61 shipped. My current fan is completely silent with the variac.

Variac Autotransformer: http://www.officebeyond.com/va-130-0300.html[/FONT]

Click to expand...

THANK YOU! LOL I had this problem too, kind of annoying when you hear the hum going on the whole time. Im going to pick one of those autotransformers up. Thats exactly what I needed.

Peace.