Another variac vs triac speed controller

[Norrath]

I would like to slow down my S+P 6" fan:
http://www.waveplumbing.com/store/i...d=4307&zenid=f1fa9725484509d68d75782ca17e5068

i have read these threads:
http://www.icmag.com/ic/showthread.php?t=117969
http://www.icmag.com/ic/showthread.php?t=112531

and this quote sticks out the most for me:

I just posted this information on another thread, but I'll include it here too...

I talked to a factory technician for Soler and Palau, the company that makes the S&P inline fans. The tech told me that Variacs are the best possible way to control fan speed of an inline or centrifugal fan.

He said that when they do long-term testing of S&P fans, they always use Variacs because it's the cleanest way to control speed, thus giving the techs a better idea of fan life since they know that the Variac is providing clean juice to the fan.

Another interesting web site to visit regarding Variacs is this site:

http://www.ietlabs.com/Variac/Variac.html

If you read the information on the above site, and if you listen to the information direct from a factory technician, Variacs are an ideal way to control speed on an inline fan.

If you do a Google search on Variacs, you can see dozens of specific references to using Variacs safely and efficiently on inline fans.

Pretty much everything stated in this thread by "Im Not Crazy" goes completely against expert opinion on the subject of Variacs.

now usually you folks agree on a matter and it's resolved. But this time around the answer is NOT VERY evident to me. I've done some research and understand the differences between variac and a triac controllers from howstuffworks and the like. My main concern is the sone level, the noise the fan puts out, and secondly the function of keeping the grow cool when needed, lights on really, and not 100% on when lights off.

no questions on the particulars, just which one should i use?

im looking for a fan speed controller less than $150, money is no object when looking at safety, but if it can be...let's get cheaper.

thx

 

[pontiac]

Variac almost killed me within the first week of use... Triac causes motor hum; therefore almost defeating the purpose of speed control, but I had no problems with it whatsoever for the last several months. The motor hum can be suppressed by hanging the fan or mounting it on cushioning...

The choice is up to you. My incident was probably an isolated case, but if you're going to get a Variac, at least get one that's not made in China.

 

[Norrath]

Variac almost killed me within the first week of use... Triac causes motor hum; therefore almost defeating the purpose of speed control, but I had no problems with it whatsoever for the last several months. The motor hum can be suppressed by hanging the fan or mounting it on cushioning...

The choice is up to you. My incident was probably an isolated case, but if you're going to get a Variac, at least get one that's not made in China.

yeah that's the problem though. i read about your incident and although it puts me off, i still want to try a variac; reading about Soler+palau's testing done with variacs leads me to believe they work well, but finding a good one would be pertinent to safe operation.

any ideas off the top of your heads? would a router variac work with an inline induction mixvent type of fan?

 

[imnotcrazy]

Firstly, Silver Oak is sadly mistaken in his post. All the info I provided was based on professional experience and knowledge AND I included references.

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....

 

[Norrath]

thanks for that info imnotcrazy - i believed you in the other threads, but so much information to take for a non electrically enthused person.

i love my S+P. it has a 2 speed operation, just change the slot the wire goes into, or just add a switch yourself. It also seems to pull very steadily, even on low which i have it on. not BLOWING air, but i have quite the length of ducting it's pulling through, perhaps 20 feet of aluminized 6" accordian ducting, then into 4" ducting and a DIY muffler, then into 2" ABS then out the window. i wouldnt fight numbers with numbers, but im running a very inefficient set up, due to security and acting stealthy in small spaces, still pulls through an activated CAN filter very well. i would buy another in a snap. if i had a bigger grow id probably up the diameter though, just cause more is better.

this is my set up:
tent air > carbonscrubber > 6"x6feet ducting > aircooledhood > 6"x8 feet ducting > S+P FAN wrapped in insulation stuffed in a minigarbagecan with 2 holes on either end > 6"x6 feet ducting > 4"x2feet ducting>DIY muffler> 4"x3feet ducting > 2"ABS out the window

harsh huh? still is AWESOME.

i was hoping to plug the wire into the other slot for high speed and then getting a variac speed control to change the RPM myself. it pulls hard and is quiet when low rpms, like on its start up. i just NEED it on so i dont get odour leaks, but if it's on, even on low speed, it's still loud, in fact it's really just the WHOOSH sound the air makes, but it doesnt make that sound and still blows quite steadily, even when it's running very slowly, like start up



well you already answered my question. so i should change my question to am i facing any cons of this set up or is it going to be easy sailing with any variac i find?

 

[qbert]

imnotcrazy is correctly describing inductive ac fans and variacs and how they work. As he has said, reducing the voltage by using a variac increases the amperage draw, and pontiac experienced that when his likely overheated and shorted.

S&P sells a speed controller for these fans, and it looks like all the other triac fan speed controllers out there: http://www.ventingdirect.com/soler-and-palau-sc-15-rotary-speed-control-5-amp/p934737?term=sc-15


I actually have that SC-15 along with a TD-125, TD-150, and TD-200 all sitting right in front of me right now.

 

[disfunktional]

The choice is up to you. My incident was probably an isolated case, but if you're going to get a Variac, at least get one that's not made in China.

i though everything was made in China now a days. lol

 

[Norrath]

imnotcrazy is correctly describing inductive ac fans and variacs and how they work. As he has said, reducing the voltage by using a variac increases the amperage draw, and pontiac experienced that when his likely overheated and shorted.

S&P sells a speed controller for these fans, and it looks like all the other triac fan speed controllers out there: http://www.ventingdirect.com/soler-and-palau-sc-15-rotary-speed-control-5-amp/p934737?term=sc-15


I actually have that SC-15 along with a TD-125, TD-150, and TD-200 all sitting right in front of me right now.

so if variacs dont give way to any qualms in the S+P fans, why not use one qbert?
or are you alluding to using a triac fan speed controller with your S+P fans because of its availability and price?

 

[imnotcrazy]

Triac-Diac (Solid-State) type contol can be had for @ $20....

He's probably using it because it's an S&P part, figuring if they sell it that it must be a viable method for speed control for those fans, although it's probably mfg by KB electronics and re-branded like 90% of the ones I see on market...

 

[qbert]

He's probably using it because it's an S&P part, figuring if they sell it that it must be a viable method for speed control for those fans, although it's probably mfg by KB electronics and re-branded like 90% of the ones I see on market...

so if variacs dont give way to any qualms in the S+P fans, why not use one qbert?
or are you alluding to using a triac fan speed controller with your S+P fans because of its availability and price?

At the time I decided what to order, I wasn't even clear on what type of motor was in the S&P's, but yes variac's price is a bit of an issue.


Basically, I wanted to see for myself about this buzzing and what kind of usable range I'd get. Figured I'd pick one up and try. Its only going on my hood fan for now.


I bought the S&P controller cause I was already ordering from that place and the S&P controller was the same price as all the rest from hydro spots (but like double the cheapy's on harbor freight or wherever - oh well, shipping would've nullified that anyway).


I already blew a couple hundred on GroZone Temp-2V controllers, which are also triac controllers - but fancy ones with temp controlled speeds with settable idles and low temp shut-offs with separate day & night settings. This is what I'll be using for the more important main ventilation fans.


I considered PLC's with proper AC frequency drives, but cost was adding up quick and ac freq drives for single phase are practically non-existent from what I've found so far. Not to mention those freq drives are pretty spendy. Plus doing the research on those started holding me back on starting growing, so yeah ... later upgrade, maybe. Of course, by the time I'm ready for that I should be in my own house and able to run whatever blaring loud centrifugal I want.

 

[Norrath]

Qbert, have you tried that sc-15 on your S+P yet? do you know if it makes a considerable humming sound?

 

[qbert]

I'll do it in a few hours when I'm home. Meant to last night, but forgot. I did have it running full bore though. I little louder than I expected. With my hand covering the sucking end it gets considerably louder and higher in pitch but keeps throwing air across the room.

 

[Norrath]

yeah, i was turned off by the astronomical sone level in the hydro shop when i bought my 6". it was like a jet's afterburner...but i could feel it across the room, and well, teh guy said it would work; he was right.

with some insulation, and it firmly in the ducting, it isnt nearly as loud as it is whirring with no ducting and insulation. ill donate 20$ to the scientist designing a silent fan! probably dyson and his henchmen...sigh. he has enough money.

/tangent.

ill be here refreshing the thread till you get her going matey

 

[imnotcrazy]

Most* of the solid-state controls have a minimum speed adjustment on the face of them as well. You use this to set the speed of the fan to avoid that "hum" people talk about when running them at very low speeds if you're worried bout noise

 

[Norrath]

Most* of the solid-state controls have a minimum speed adjustment on the face of them as well. You use this to set the speed of the fan to avoid that "hum" people talk about when running them at very low speeds if you're worried bout noise

considering, and i trust your knowledge, that S+P fans do not have the suction on par with centrifugal fans, if i put it on very minimum on the triac style speed control, id fear i wouldnt get any suck at all...considering my...length of ducting to be abhorrent.

ninjaedit - 3 cheers for no hum though!

 

[qbert]

You can turn the 200 pretty low before the hum is louder than the fan, and its not like the hum really gets louder, the fan just gets quieter comparatively. The hum is pretty quiet compared to the fan at full speed. This point is at 12 o'clock on the dial with it wired on the S&P's slower circuit. On the high speed circuit I could turn it all the way down and not hear a hum.

The S&P controller has the fine low speed adjustment on the box underneath the face, but I didn't mess with it. At full low on the dial wired through the low speed circuit, the S&P was moving a pretty small amount of air. It didn't seem to flinch when I covered the intake side with my hand, though. Got a little louder and higher pitched again but kept up the airflow. Suppose I should've held a book over it or something to cover it totally. Guess I didn't think of that when the bubbler was calling my name.


Oh, yeah, and I Kill-A-Watt metered the TD-200. ~130 watts on full speed through the controller and still ~90 watts at minimum speed (with factory default on the minimum speed adjustment pot). So, its not a linear decrease like say a halogen light on a dimmer.

 

[grow nerd]

Variac almost killed me within the first week of use... Triac causes motor hum; therefore almost defeating the purpose of speed control, but I had no problems with it whatsoever for the last several months. The motor hum can be suppressed by hanging the fan or mounting it on cushioning...

The choice is up to you. My incident was probably an isolated case, but if you're going to get a Variac, at least get one that's not made in China.

What happened?

 

[sunnydog]

Quiet

Quiet

Hi Norrath.
Have a look at my keeping quiet thread, I bumped it. This may help your problem.
http://www.icmag.com/ic/showthread.php?t=94257
Also, my concern with a Variac is the dial could get turned up to high and roast your fan.

SD

 

[Norrath]

Thinking about revamping the runs with solid ducting though, my system is the way i want it, now to improve on the individual components

thanks for the link and write up sunnydog! rewrapping another layer around the accordion duct would be a good, albeit pricey solution. yeah ill do a better job on my "insulation can" around my mixvent and get hard pipe, might even be able to turn the fan on low with that much better flow........hmmmmmmmm

What happened?

tripped something and sparked itself i believeeeeeeeeee...... actually i put cinder blocks under my ballasts right after learning about pontiac's woes some time ago..

 

[Budsworth]

Called up Can Fan. They specifically told me NOT to use a solid state "Speed Controller" with my 10" Max Fan. Told me it would dramatically shorten the life of my specific fan. Then they tried to sell me their Can Fan version of the variac for a couple hundred bucks. Bought one for $50 online. Works like a charm.