Using a variable speed controller for your inline fans

[Hackerman]

Anyone doing this? I use variable speed controller with my Hydrofarm Active Air ACDF6 Centrifugal fan (my exhaust fan).

I tried to use this same speed controller with my Hydrofarm ACFB66" booster fan (my intake fan) and it wouldn't work properly. I did a little reading (still doing) and it seems there are 2 different types of motors in these 2 fans and they require different types of speed controllers.

While I was reading, I saw a sticky here that said you can't use ANY speed controller with a single speed fan. I don't know how old that sticky is or if it's accurate but it got me thinking if I am OK with the speed controller on these fans. ( http://www.marijuanapassion.com/forum/showthread.php?t=1965 )

Anyone using speed controllers on their fans?

 

[TrollMaster5000]

no they really dont work with the brushless non capacitor motors ( the small booster fans ) multi speed fans are of this type actually have more then one set of windings on the motor one winding is longer then the other creating a set amount of magnetic force when turned on one of the settings
and also even though they are sold to be used with the larger extraction fans
and alot of people use them
a capacitor start motor runs on a rolling wave length of current
and that rheostat fan controller puts out a square wavelength that is why you often hear that growl when you turn it down
the only true way to turn down that capacitor start fan properly and using the proper wavelength shape is with a variac style controller or a actual step down transformer

 

[sawhse]

Yep I use them on both of my fans. My 4 and 6 inch fans. One is called a speedster and the other is a Growbright. Both work great. My can max 6 has high and low switch and I just set it on high and use controller.

 

[Hackerman]

no they really dont work with the brushless non capacitor motors ( the small booster fans ) multi speed fans are of this type actually have more then one set of windings on the motor one winding is longer then the other creating a set amount of magnetic force when turned on one of the settings
and also even though they are sold to be used with the larger extraction fans
and alot of people use them
a capacitor start motor runs on a rolling wave length of current
and that rheostat fan controller puts out a square wavelength that is why you often hear that growl when you turn it down
the only true way to turn down that capacitor start fan properly and using the proper wavelength shape is with a variac style controller or a actual step down transformer

Are the inline fans that we all use like the Hydrofarm Active Air ACDF6 Centrifugal fan (my exhaust fan) the multispeed type? Or, should we not be using these speed controls with them?

 

[Hackerman]

Yep I use them on both of my fans. My 4 and 6 inch fans. One is called a speedster and the other is a Growbright. Both work great. My can max 6 has high and low switch and I just set it on high and use controller.

This was another thing I ran in to. I bought the same Can fan and took it back because I was hesitant about using a multi-speed control in addition to a 3 speed switch.

 

[sawhse]

Yep felt the same way the manual said you can't use another type of controller wasn't sure what it was. So I goggled the other type and it was okay to use speed controller on that model

 

[Kraven]

no they really dont work with the brushless non capacitor motors ( the small booster fans ) multi speed fans are of this type actually have more then one set of windings on the motor one winding is longer then the other creating a set amount of magnetic force when turned on one of the settings
and also even though they are sold to be used with the larger extraction fans
and alot of people use them
a capacitor start motor runs on a rolling wave length of current
and that rheostat fan controller puts out a square wavelength that is why you often hear that growl when you turn it down
the only true way to turn down that capacitor start fan properly and using the proper wavelength shape is with a variac style controller or a actual step down transformer

Exactly what he just said...good post!!

 

[TrollMaster5000]

Are the inline fans that we all use like the Hydrofarm Active Air ACDF6 Centrifugal fan (my exhaust fan) the multispeed type? Or, should we not be using these speed controls with them?

thats a capacitor start fan so you would need a variac controller in the proper amperage for your fan which is actually a step down transformer and not a rheostat controller and you would use the fan in the highest setting and then make adjustments through the variac and not on the fan

i know almost every shop sells them for the inlines but its not what you really need
that controller is actually a router / single speed drill ( which are both non capacitor brushed motors ) controller that has been remarketed

im not saying it doesnt work
just that its not right

 

[TrollMaster5000]

variacs are like $60-$100 is why most people jump on the on the $20 rheostat

 

[Hackerman]

Hydrofarm sells this and recommends it for use with their fans. What's up with that?

hxxp://www.hydrofarm.com/product.php?itemid=8589

 

[TrollMaster5000]

notice where it says stall speed range eliminated to prevent stoppage
they just made it to where it wont turn down to less then 50% or where ever the fans normally stall its still a rheostat / dimmer

 

[TrollMaster5000]

if you could sell a dimmer that would slowly burn out a fan
and profit from the sales of the dimmer would you ?
with the proper dimmer your fan will last longer and be safer to operate
i hate to say it but there is no money in that
and these companies know this

 

[Hackerman]

So, I should be using something like this...

hxxp://www.ebay.com/itm/New-VARIAC-Output-0-130VAC-3AMP-60Hz-NIB-/261479411614?pt=LH_DefaultDomain_0&hash=item3ce1632f9e

 

[TrollMaster5000]

yes
your fan would last longer then with the other kind
and it would make the motor run quieter then with the other one
it takes away alot of the motor hum

 

[Hackerman]

Here is the devil's advocate. Apparently, he is against the variac...

Originally Posted by imnotcrazy
Secondly, I was and still am adamant against the use of a variac on a permanent split phase capatitor type motor. These are the type used in Vortex, Fantech, Canfan and Eco Plus Centrifugal type inline fans.

A variac is usable on the S&P type fan, as per their technician (and I found out by looking into the fans themselves) because they use a Shaded Pole Type motor. These motors have a design that limits current through the motor windings regardless of voltage applied to the motor.

Permanent Split-phase capacitor type motors do not have the ability to do this. And the motor requires the same wattage. This via Ohm's Law means the motor pulls more current. That would be alright if the motor responded like a resistor but it doesn't. Any speed control provided by a variac is because of reduced torque, but an AC motor's speed is determined by the frequency of the applied voltage (60Hz USA).

Therefore, the motor will continue to pull more current in an overload type of situation until the motor windings burn or some protection circuit trips. Most variacs do not have a fused secondary winding and because the primary side current remains low, the primary side fuse will NOT protect the motor. This eventually creates a short circuit either in the fan motor or at the variac secondary winding.


To add, I never originally considered the S&P type fans because of their Axial design. They are much less efficient when dealing with static pressure and any length of ducting will seriously effect their performance. I wouldn't even consider using one for a carbon filter....

 

[Hackerman]

Still playing with this and I have another question, if I may.

Is the Hydrofarm Active Air ACDF6 Centrifugal fan that I am using as my exhaust fan considered a "brushless motor"?

Thanks

 

[Hackerman]

Go digital then

Can you be a little more specific, please? Do you mean something like the Evolution digital fan controllers you posted earlier?

 

[The Hemp Goddess]

Hackman, I gotta tell you that in real life, in actual practice over many years, a controller like the $20 Speedster works just fine. I have a 6" Vortex that I have had for so many years I can't remember when I bought it (but at least 7 years ago) and have never had one bit of problem with. I have a backup fan in the closet since I absolutely cannot be without a fan with the 1000W but there it sits, gathering dust. Maybe this is getting a little more complicated than it needs to be?

 

[Hackerman]

I always make things more complicated than they need to be. Part of the illness, I guess. LOL

For 30 years, the only ventilation I had was a bathroom fan on the ceiling. LOL Worked fine.

But, like I said before, this is a hobby for me so experimenting and learning new things is part of the fun.

My CAP Speed controller has a label on it that says, "Do not use with brushless type motors". And, the inline fan I am using (and the ones we most use) are brushless motors... are they not?

 

[zipflip]

IF YA GOT THE COIN THEN A VARIAC IS A MAJOR PLUS over tehm chincy speedster controller IMO. I got 4 variacs . one on every single canfan I use when running. speedsters work but ya always got tham dang hum whining sond when ya dim it down. u egt a variac and hook it up to that and all that annoyin hum and whining noise goes away. also my fans seem to last do better on them vs the speedsters I used to use years back. after getting the first variac way back when I jumped on it and got 3 more to replace the speedsters I loved them so much. maybe odd annoyin noises that are constant don't bug u as much as me but if ur one who is driven nuts over anoyin noises and don't mind paying extra in life for piece of mind as well as performance etc then definitely opt for vaiacs. JME and opinion on controlling speed for these inline fans.