No hum vent fan controller?

[jsguitar]

For venting steam for my basement brewery project I bought a valueline 6" centrifugal fan and a CAP variable speed controller. I got the fan mounted and it works great, and for around $80 is a bargain I think.

However, the speed controller makes the fan hum really loud on low and is therefore very annoying. I kind of got screwed on that. It shouldn't have been sold as a fan controller I think. It actually says router controller on it if that matters.

Is there a way to controll this fan without the hum? I was hoping to just buy something, but if I can make it that's fine. If anyone has made or has one that has worked well please let me know. Thanks.

Once I get a little further along I'll starting putting some pics up. Right now I'm doing more cleaning and organizing than building.

 

[mattd2]

Why not just let it rip 100%?

 

[jsguitar]

Why not just let it rip 100%?

A couple of reasons. It's over 400 cfm's and I don't really need or want the noise, or air removal that it's capable of during the majority of the process. I just need the full power during the boil really. A lower speed during the rest of the process should remove enough moisture without the above issues.

 

[jsguitar]

So I figured out that the speed controller I was sold is really just a dimmer switch which isn't great for this application. I've seen a few users here using them actually and they're marketed as fan controllers. They're often called the "speedster". I'm not sure, but I would think using something like that wouldn't be good for the fan long term.

I reread Kal's info and had forgot that he ended up using a three position fan switch. Apparently, they use a separate capacitor for each speed. To get a safe and effective way for completely variable control of a fan would require an expensive variable frequency drive. $$$$ I'm going to do what Kal did but get a Hunter 3 position switch rated at 2 amps and get rid of my speedster.

 

[plaufer]

I think you want a Variac (or Variable Autotransformer). They can be had for around $100 new.

 

[artbrau]

Look at my "basement brewery build" thread. See if this might help. Excerpt:

Earlier in this thread you can see the Fantech FKD10 fan I use on the exhaust hood. I also used the the specified fan speed controller. The fan is 3amps and the controller is rated for 5.

Problem is, I've blown out 3 of them. They work fine for a few brew sessions then "pop." The sound of sparks, the smell of ozone and it's done. I don't think the wiring is faulty because the controllers do work for a while.

I went looking for a heavy duty controller but they are much larger and much more expensive (penny wise...?) So I got this one

It's rated for 15 amps and has a fuse. The problem is, it's designed to plug in a fan, not wire in-line as a switch. I thought about complex hacks involving re-wiring the insides and got out my soldering gun before I realized I was way overthinking it.

I just cut off the plug, wired it together and used it as a jumper for the outlet where the fan would plug in. Then I took the beheaded cord that was supposed to plug into the wall and wired that in the way a switch would go. I flipped the breaker back on and Bob's your uncle! Works like a charm. We will see for how long. Hopefully, the fuse gives me a cheaper failure mode.

You can see where what was the plug cord comes out where the switch used to be. The ground wire in the cord does connect to ground. Where a fan would plug in, you can see the stubby tail of the plug with a wire nut shorting the two current carrying wires.

 

[jsguitar]

Look at my "basement brewery build" thread. See if this might help. Excerpt:

Thanks. That's actually the controller that I have, just rebranded! I don't like it obviously. Does yours not hum if you use the variable speed feature? I'd read that someone had someone at can fan tell them that that controller was bad for their 12" fan. I'd call fantech and see if you get the same answer just to be safe. The problem is the way it chops the current, basically causing the motor to stop and start rapidly (if I understand it right).

Maybe it would just take a really long time to cause trouble? I have no idea. Looking into this opened up a whole can of worms. If you google the subject you'll end up in all kinds of "growing" forums. Those guys know a lot about that stuff.

 

[AssistantBrewer]

I am an EE. Variable autotransformer (Variac is a brand name like Kleenex) is the right answer for AC full range no hum motor control. They work by varying the AC voltage, not the duty cycle as do solid state controls. They're basically a one coil transformer wound around a cylindrical core with the output connected to a center tap wiper that allows the turns ratio to be adjusted by rotating a dial. They're very efficient when run under rated capacity. See the variable autotransformer section at the end of this Wikipedia article: http://en.wikipedia.org/wiki/Variac

You won't be able to do hum-free using typical low frequency pulse choppers, at least not without building a tank circuit (low pass filter), which at line voltages is beyond the typical brewer.

 

[jsguitar]

Thank you plaufer and AssistantBrewer for the variac suggestion. I had read that suggested and almost bought one but just wasn't sure if that was the way to go for sure. Apparently Can Fan suggests a variac as well. I'm going to go that route. I found one here:
http://www.circuitspecialists.com/prod.itml/icOid/7674

It's rated at 5 amps and with shipping is a little over $60.

 

[artbrau]

Thanks. That's actually the controller that I have, just rebranded! I don't like it obviously. Does yours not hum if you use the variable speed feature? I'd read that someone had someone at can fan tell them that that controller was bad for their 12" fan. I'd call fantech and see if you get the same answer just to be safe. The problem is the way it chops the current, basically causing the motor to stop and start rapidly (if I understand it right).

The Fantech-recommended speed control is solid state. I get no hum with this controller. so maybe your fan is finicky.

 

[jsguitar]

Maybe some fans are more finicky than others. I did read a lot of similar complaints on the unit though.

I went ahead and got the small variac and it does just what I'd hoped. So, I'm happy now.

 

[Shockerengr]

I am an EE. Variable autotransformer (Variac is a brand name like Kleenex) is the right answer for AC full range no hum motor control. They work by varying the AC voltage, not the duty cycle as do solid state controls. They're basically a one coil transformer wound around a cylindrical core with the output connected to a center tap wiper that allows the turns ratio to be adjusted by rotating a dial. They're very efficient when run under rated capacity. See the variable autotransformer section at the end of this Wikipedia article: http://en.wikipedia.org/wiki/Variac

You won't be able to do hum-free using typical low frequency pulse choppers, at least not without building a tank circuit (low pass filter), which at line voltages is beyond the typical brewer.

Sorry, but a variac will only work on the same type of motors that the 'chopper' circuits will work with. (which for ac means a universal, brushed motor)

If the fan is humming with the dimmer, it means it's an induction motor, and the humming you hear is the current surges puslating the motor.
Not knowing the exact design, I can't make a suggestion right now, because different motors require different designs for speed control, with some types not really having a simple solution. Typically for these types of motors, speed control is done in the basic motor design by having multiple stators/poles that can be reconfigured.

Here's the deal with the variac, it'll probably work, for a while...but induction motor speed is based on frequency, not voltage. The reason it'll work for a while is you are limiting the power that can go to the fan, causing it to fall on the back half of the torque curve...but it'll probably be unstable and run a lot hotter than it should (as well as pull more current) and eventually, you'll ruin the fan.

by far the simplest thing to do is to install a damper and limit the flow.

 

[jsguitar]

Here's the exact fan:

http://www.amazon.com/ValuLine-Centrifugal-Fan-435-cfm/dp/B0033BONPQ

I mentioned earlier about using a variable frequency drive, it sounds like you may agree with that as a way to control it?

The problem is those are way more than the fan. I only paid $80 for the fan. I'm thinking that since the variac seems to work as far as controlling the speed in complete silence and that I'll only be using it once in a while, that the fan would be fine. Thoughts?

I'm guessing the dimmer type would also be bad for the fan in addition to the annoying hum.

If there's another solution it'd be good to know. The people that sell these types of fans often have them linked together with these cheap dimmer type controllers and clearly they're not all compatible. It'd be nice to have some consensus on what works and what doesn't for us clueless shoppers.

Thanks.

 

[Shockerengr]

little hard to tell the type, for that size it could be a shaded pole, or a permanent split capacitor style motor. (although that's not really that important for this discussion)

Ultimately, if I were you, I'd skip the Variac, because I'm doubting that it'll be enough quieter to justify the cost. The reality is it works in much the same way as the other controller: limiting the power input to the motor. It does have a much smoother waveform, so it'll likely be somewhat quieter, but you'll still get a whine from the motor because your running it well below the speed that would be dictated by the operating frequency...and the further away from that speed, the more of a whine (and wear) you'll get.

 

[jsguitar]

little hard to tell the type, for that size it could be a shaded pole, or a permanent split capacitor style motor. (although that's not really that important for this discussion)

Ultimately, if I were you, I'd skip the Variac, because I'm doubting that it'll be enough quieter to justify the cost. The reality is it works in much the same way as the other controller: limiting the power input to the motor. It does have a much smoother waveform, so it'll likely be somewhat quieter, but you'll still get a whine from the motor because your running it well below the speed that would be dictated by the operating frequency...and the further away from that speed, the more of a whine (and wear) you'll get.

Ok, thanks for the input. As I stated earlier, I already have the variac and tried it out and it's completely silent, all the way from no power on up. The other controller creates a LOUD hum, especially when turning the speed slower than say 3/4 speed. I didn't hear a whine at all with the variac fortunately. I appreciate your advice but I guess I'll just use it since it seems to be working as I wanted it to.

 

[Shockerengr]

Ah, didn't know you already had the variac. If it works, go for it. Keep an eye on the motor, and if you notice it running hot, just keep the speed up a higher

 

[jsguitar]

Thanks! I'll do that. I'll update after awhile if anything seems amiss.