Cohesive Air / Hoot Chute: Read this

[Hoot]

If you are considering implementing a centrifugal blower, such as outlined in my article, http://www.overclockers.com/tips461/index.asp from a few weeks ago, read on. Ditto if you already have.

In my article, I had recommended the Dayton 170cfm DC blower, Model 2C646. Dayton also has a 130cfm AC version of this blower, Model 2C647. If you have not gotten the blower yet, get the AC model. If you have the DC version, don't panic. It works just fine.

I wanted to see how the AC version would work, so I bought just the motor. Upon hooking it up, it performed as well as the DC one, with the exception that it was stuck running at full speed and the vibration was hard to tolerate. Unlike DC motors, you can not regulate the speed of an AC motor as easily as lowering the voltage. They are synchronized to the 60Hz line frequency and that, combined with the number of poles, contributes to the speed.

So, I had written off the Ac motor as a failed experiment and put it on the shelf as a backup. In a post I read last night, it was tossed up whether an AC light dimmer would work. I took this reasoning one step further and picked up a Bathroom Fan speed control, which works on a similar principle. When I got home form work, I wired it in and the results are stunning. You can slow the fan down to almost a complete stall, or run it full tilt. No complex regulator circuits to build, no brush noise (DC version). As I type this, the only way I can tell the blower is running is to look at it and verify the cage is turning. It is quieter than the Northbridge and GPU fans combined with the HDDs. It still gets loud at full tilt mind you, but performs very well at lesser speeds, just like the DC model.

While I'm sure that those of you with the DC version have no desire to throw more money at the project than you already have. You can convert your unit for the cost of an AC motor (appx $20.00) and I got the speed control from Menards for $14.95. You may be able to source both pieces for less through a surplus dealer. I did not try a light dimmer, which cost considerably less than the fan speed control. The controller is rated for 3A of load and has EMI surpression built into it (unlike some cheap light dimmers).

One caveat. If you have read the article, You know that the original design was based upon using one air source to both cool the CPU and provide through-case ventilation. When you turn the AC speed control way far down, it still cools the CPU fine, but doesn't provide sufficient through-case airflow. Normally you would not run it that slow though.

I apologize for not researching this angle more when I was doing the original article. I failed to think far enough "outside the 9 dots". I will continue to work on the last segment of the original article, detailing the variable DC regulator construction.

Hoot

[William]

hey hoot, where do I buy a hoot chute?

[sfa ok]

Hoot, how heavy is the AC blower? Would I need to add support to mount it to my case?

[Hoot]

I didn't pick that nickname. ;D Someone else started it and it took root. If you're not kidding, you build it, not buy it. You can buy the components though. Or, did you mean where can you get the blower?

Hoot

[William]

i want to know where to by the blower, sorry for the confusion ;-)

[sfa ok]

William: Grangier (sp?) has it.

[William]

i know what you are talking about, do they have a website?

[sfa ok]

http://www.grainger.com/

The DC part # is 2c646, from there you can go to other small blowers.

[Magistrate]

One caveat. If you have read the article, You know that the original design was based upon using one air source to both cool the CPU and provide through-case ventilation. When you turn down the AC speed control to a certain point, it still cools the CPU fine, but doesn't provide sufficient through-case airflow.

Unfortunately, that is one huge caveat. The main attraction for me was that the blower could potentially replace all the other noise producing fans in my case.

Could you define "turn down the AC speed control to a certain point".

I'm assuming this point is where the noise is no longer audible. Can you turn it up in order to get better total case cooling? If so, how much more noise do you have to tolerate?

[Hoot]

Just got back from riding bikes with my 7 year old.

The AC version weigh about as much as the DC version, just under 4 pounds. You don't need to reinforce the side panel to use it. The majority of the weight is close to the surface.

Go to the Grainger Web page and up at the top is a search engine. Click on manufacturer part number and key in 2C646 (DC) or 2C647 (AC). If the company you work for has an account with them, you can get about 5-10% below the listed price.

I was sincere when I referred to how quiet it is. At 50% speed, it's about as loud as when the forced air furnace is running, as heard through the vents on the next floor. If I had a place to drop off some .wav files, I'd record it compared to several different sized case fans (80-92-120mm) and you could be the judge. It is as quiet as the DC fan without the crickety brush noise. When it is cranked wide open, there is a low frequency rumble that might be improvable with some deadening materials effort. I haven't tried yet. At 50% speed, running prime95, the CPU is only 2C warmer than at full tilt.

Hoot

[mEKbOY]

What kind of power do these units use or do i have to mod it to work with my computer cuz im not to famaliar with wiring and such.

[Hoot]

I just finished a lengthy benchmarking session and I'm bushed. MEK, it runs off of 110 AC.

Yet another revelation. At full speed it does not cool any better than at 80%, but it sure makes a lot more noise. I think this may be the result of backpressure from the duct underneath it. That's actually good news, because at 80% the sound is tolerable. So what did ole Hoot find? Here's some results.

First I want to qualify the term Inaudible as making less noise than the fans on the Northbridge and GPU, combined with the HDDs. You do need an 80mm circulation assist fan when running Inaudible, to keep the through-case flow satisfactory. I used a Sunon 36cfm (very quiet) to do the trick. Okay, now those results:

Speed--------80%--------50%--------Inaudible
1333 Mhz----32.1C-----32.9C------35.0C
1400 Mhz----34.8C-----35.8C------38.0C
1450 Mhz----36.9C-----38.2C------40.7C
1500 Mhz----39.4C-----40.5C------44.7C

In practical use, Inaudible is fine for email, surfing, forums, etc. 50% is fine for 3D gaming, CAD rendering, compiling, Scientific Modeling, just about anything that I could throw at it. 80% would be for chasing that elusive one more step faster, that we lie about and put in our signatures, like we run that all the time. ;D The majority of the noise at 80% is air rushing, which indeed it is doing. I have not tried any sound abatement techniques yet. That will be the "Icing on the Cake". I am running with the speed control set to the inaudible mark as I write this. My CPU temp is 25.8C :-)

Hoot

[William]

the price of the unit took me back, but I was expecting to spend that much in normal fans. I am think that I am going to have to mount this differently though. I think parallell to the case running a duct to an SK-6(for my celey) should work quite well. And with running an Intel chip I should get great temps running at a lower RPM. How do you have this sunon helper fan positioned Hoot?

[Hoot]

In my mid-tower, it is on the bottom of the front exhausting, like I'll feel in 5 hours when my alarm goes off. :D

ZZZZZ

[William]

Hoot (Jul 06, 2001 12:13 a.m.):
In my mid-tower, it is on the bottom of the front exhausting, like I'll feel in 5 hours when my alarm goes off. :D

ZZZZZ

sleep tight hoot! You have had a busy day.

[CalCoolage]

Hoot (Jul 05, 2001 07:46 p.m.):
... I took this reasoning one step further and picked up a Bathroom Fan speed control, which works on a similar principle
Hoot

You can find this also called a Ceiling Fan Speed Control (3 amp). Since you can find ceiling fans everywhere, you might be able to find this type of control nearby.

http://www.mcmaster.com/ has one for $12.77, their number 2042K58.

[Magistrate]

Does the AC model still have the brush noise problems of the DC when running above the 'inaudible' level?

[Hoot]

No, the AC model (2C647) is brushless and very quiet when you are not running it at full speed.

Hoot

[Magistrate]

So Hoot, are you going to add a section to your electronics writeup for people buying the AC model?

[Hoot]

I am currently making the AC speed control mount and interface. I will probably submit it as an article. No time frame yet.

Hoot

[mackstann]

Once I get some money, I am definitely doing this. And about the fan speed control--what I am going to do is go to the music store and buy a black volume knob for a guitar. You might want to consider it, I'm sure it would look alot cooler than an ugly knob meant for the pooper. :)

[McCarthy]

Great article, Hoot. Love the concept, especially since it seems to work.

Question I have is how adversely a couple feet of ducting would affect the performance. What I have in mind is this: Build an enclosure to hold the motor, make one side of the box a filter, duct from box to case, could even come through the back and use an elbow to blow onto CPU. Why? Looks, top of desktop space, and having a filter benfits the computer guts and air breathing residents of the room both, all good things. But not if it hurts performance such that the motor has to be run significantly faster and ends up creating more room noise from it's isolated position than the direct method you used.

First post here, your idea has already spread and got me enthused enough to register over here. Now, where am I going to get the time to read two site forums a day? <g>

Thanks!
McCarthy

[Hoot]

I don'y have enough time to even read one thoroughly. ;D There is nothing wrong with using duct to isolate the blower elsewhere, but most people make the mistake of using ducting made from some corrugated material. That is the worst thing you can do. It really knocks down the air velocity. If you can find ducting made from smooth-walled material, you should not see any reduction in effectiveness.
In my case, I use a mid-tower and towers work very well down on the floor. Also, the air is cooler down there. There are a million ways to take a concept and experiment with it. That is the fun thing about tinkering.

Hoot

[Froggy1]

Hoot (Jul 10, 2001 08:53 p.m.):
I don'y have enough time to even read one thoroughly. ;D There is nothing wrong with using duct to isolate the blower elsewhere, but most people make the mistake of using ducting made from some corrugated material. That is the worst thing you can do. It really knocks down the air velocity. If you can find ducting made from smooth-walled material, you should not see any reduction in effectiveness.
In my case, I use a mid-tower and towers work very well down on the floor. Also, the air is cooler down there. There are a million ways to take a concept and experiment with it. That is the fun thing about tinkering.

Hoot

If you are looking for good ducting, go to a "race/speed shop" and buy the right size brake duct. That stuff can turn 180 degrees with no velocity loss. Cuz cooling rotors is a VERY big deal for race cars. Not cheap though.

[ThatDumbGuy]

any eta on part 3 yet hoot? don't mean to bug you, im just electronically dumb thats all...


thanks for the articles!

[PDL]

Question for ya Hoot.
Would there be any negitive effects of using a blower with a round outlet. It would have the same fan characteristics as yours, but with a 2 1/8" round outlet. (grainger # 4C440)
I believe it is rated at 54cpm.(not sure how to read those ratings listed in the catalog)
I have access to one I can try and I already have a round hole about that size in the side of my case cover.
Thought I better get this done before it is pattened...hehe

Thanks Hoot!

[PDL]

I have lowered my temps by 7 degrees(celsius)!!!
WOW
:)
Using a "squirrel-cage" blower running at about half speed on a dimmer control. Noise is about the same as having the 26cfm fan on the heatsink and an 80mm exhaust out the top of the case. This is a 'used' blower to try out and I will get a new one later.
Better than I had hoped.
Also, this is with a Taisol aluminum base HS, can't wait till the SK6 gets here. I don't think I will ever use the Delta fan that I ordered with it. Should be interesting to see how much more efficient the copper base is on the SK6.

I'll post here later on that change.


Thanks again to Hoot........way ta go!!!

[befamfivh]

Originally posted by Hoot
whether an AC light dimmer would work.

I'm not sure about using regular dimmers for AC blowers, but they seem to work fine for AC fans. I've been using a $4 dimmer switch wired to an extention/extra outlets cord to control a few AC fans for a while now. No problems yet...

I'm pretty sure that dimmer I have (and others in the same price range) wouldn't be able to handle the 115v .74a draw of that blower, though.

[Glint]

I have nothing but good to say about your cooling tactics. This being my first post I better get wordy d**n quick. Coming from a mechanics backround, using what amounts to a scaled-down supercharger for cooling is a marvel of ingenuity and thorough thinking. Ideas like this are the things that are drawing me to computers, that and my ever feverent roommate.

[NedClocker]

Does any body know what the part numbers are for these fans now? I can't find these part numbers in granger.com.

edit - Never mind. I called the Granger store and the parts numbers are still good. I'm going to pick up one of the DC fans today. :D

[Arkaine23]

Gotta love that airflow!

Heya, Glint! Nice to see you on the boards. Welcome to these wonderful forums!! I can't wait to see what you come up with when you finally start building your own computer. I've been needing someone to make a custom uber-cool waterblock, not to mention someone to compete with for the fastest computer on the block.

<--Glint's roommate

[MEAT BAG]

Those fans are loud though

[NedClocker]

Originally posted by MEAT BAG
Those fans are loud though
They are not that bad when you are running them on 5v. And they do a terrific job of cooling.

[Randyman...]

You can use a standard "600Watt 5Amp 120VAC" Fan Speed Control for these Shaded Pole/Squirrel Cage blowers up to 4.5 - 5 Amps. You can pick them up at the local home improvement/hardware store for about $8-$10. Some will even have a "Low Speed Adjust" to keep the lower end of the adjustment from stalling the fan (or to use as a minimum speed for heat security).

I use a "Dual Blower/Single Motor" unit to cool my room (Exhaust), and it pulls 3.5Amps at full tilt. The Fan Speed Control works just peachy. I installed it in a exterior "Surface Mount Single Gang Box", and wired it accordingly. It will get a bit warm, as it is converting the leftover power to heat!

PS - Check eBay, as I just bought my 275CFM blower as "New Old Stock" for $10 plus $11 shipping (It is like a $50 blower!). Not bad...

Later :cool:

[clocker2]

I did not try a light dimmer, which cost considerably less than the fan speed control. The controller is rated for 3A of load and has EMI surpression built into it (unlike some cheap light dimmers).


Hoot
I have used the "cheap" light dimmer to regulate my Muffin XLs.
It works, but as you might suspect , the lack of suppression leads to fan hum.
At the time I bought it I was uncertain if the concept would work, so I was unwilling to spend the extra bucks for the more expensive fan control.
If I was still using those fans I'd definitely recommend the fan speed controller.

[Samene]

So... years later.... what was the eventual conclusion on the Dayton blowers? I have one but it runs hot whether it is speed controlled or not. Did everybody who tried this end up with the blowers burning out or are they still running for you?

[DaPoets]

cough cough hack weeez... *fans dust from old thread w/ some interest....

[thideras]

Thanks for the bump, I may have to try this in the future :)

[Tekko]

Holy thread necro batman!!