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Old 11-06-2010, 03:03 AM   #1
gypsyhead
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I've been reading a lot about DIY counterflow chillers lately and I'm seeing that the marks for efficiency definitely come with the convoluted type, but the price tag is a bit of a hang up. And it seems like the 3/8" copper-in-garden-hose is the cheap, useful alternative.

But looking at prices, you can get 50' of 3/16" copper tubing for about the same price as 25' of 3/8" tubing, and if you twist the 2 x 3/16 together, you'll get a convoluted flow with more surface area exposed than a manufactured 3/8" convoluted copper tube.

I can see the downside is having to rig a "Y" gate at the front and back, but that's easy enough with some basic brazing skills.

And yes, if you're worried about cloggage from hops, etc. that could be an issue, but you would just have to put a strainer in front of the chiller line, right?
Looking for more opinions on this one before I lay down the cash (which should still only be ~$70)
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Old 11-06-2010, 03:14 AM   #2
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I would love to hear more. It's not my money or beer...I say do it!

 
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Old 11-06-2010, 03:59 AM   #3
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right, did the math, it obviously restricts your flow by 1/2 as compared with 3/8", but would be a more efficient chill, so could hypothetically maybe work in 1 shot
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Old 11-06-2010, 11:04 AM   #4
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Quote:
Originally Posted by gypsyhead View Post
right, did the math, it obviously restricts your flow by 1/2 as compared with 3/8", but would be a more efficient chill, so could hypothetically maybe work in 1 shot
Just roughing out the numbers, a single 3/8" OD tube (0.311" ID) would have about three times more cross sectional area than two 3/16" OD (0.1275" ID) tubes. The smaller tubing will have a much higher resistance to flow. I would think that you would be lucky to be able to push even 20% as much wort through the smaller tubing as you could with the larger stuff given equal head pressure. IMO, the reduction is much more than you realize and this would reduce the chillers efficiency. Obviously, if you slow the flow sufficiently, you could chill in one pass with almost any size tubing, but it would take longer to do so. I prefer to run a high flow rate for both the wort and the cooling water, but I'm pumping through a CFC and back to the kettle for multiple pass chilling in a continuous loop. Wanna race?

 
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Old 11-06-2010, 02:18 PM   #5
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I have had my 3/8" CFC clog with pellet hops & break material. I'm planning to build a 1/2" CFC to avoid the problem.

I can see where you may have a lot of problems with 3/16".

Ed

 
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Old 11-06-2010, 04:08 PM   #6
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There really is nothing convoluted about two 3/16" tubes twisted. The path inside of each tube is still smooth resulting in laminar flow. Couple that with the fact 3/8 tube flows nearly double what two 3/16 tubes would (you have to compare the area of the tube, not the diameter). Two quarter tubes would be closer, but still not there.

IMHO, if you want to try to disturb the flow, get a half inch tube and place some 1/8-1/4" dimples using a rounded off punch or something similar every couple inches.

 
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Old 11-06-2010, 04:21 PM   #7
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FWIW

3/16" OD tubing ID= 0.1275"

3/8" OD tubing ID=0.311"

3/16 interior cross sectional area = 0.0128 sq inches

3/8 interior cross sectional area=0.0760

So double the 3/16" for a combined interior cross sectional area of 0.0256 sq inches

0.0760/0.0256=2.97, say round to and even 3 times more cross sectional area for the single 3/8" OD tubing. Factor in the increased resistance of the smaller tubing and you will probably get something like a four or five fold increase with the single large tube over the twin smaller tubes.

 
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Old 11-06-2010, 05:19 PM   #8
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the convoluted part comes in the water flow, not the wort, but yeah, the reduced flow is making this seem like a worse and worse idea, thanks for the clarification guys, i was doing math with 3/16 as the nominal not the OD, and getting exactly 1/2 the flow, but factoring in everything else, yeah, severely cuts it down.
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Old 11-06-2010, 05:37 PM   #9
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Quote:
Originally Posted by gypsyhead View Post
the convoluted part comes in the water flow, not the wort.
That makes sense. The convoluted CFC chillers do a good job of disturbing the flow of both fluids.

In addition to the small dimples to disturb the wort flow, a previously posted idea about wrapping thin copper wire around the outside of the inner tube prior to inserting into the garden hose would work well enough. Might have to solder every little bit to hold it in place.

I will probably implement these ideas when I build mine.

 
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Old 11-06-2010, 07:32 PM   #10
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Quote:
Originally Posted by RedLight_Brewing View Post
In addition to the small dimples to disturb the wort flow, a previously posted idea about wrapping thin copper wire around the outside of the inner tube prior to inserting into the garden hose would work well enough. Might have to solder every little bit to hold it in place.
IMO, none of that would be worth the time and effort. I would bet that the difference would be quite trivial if even measurable with our crude thermometers. I would also think that the cooling water flow would be fairly turbulent regardless with the tubing more or less randomly positioned within the hose often brushing one side or the other with little uniformity throughout it's length.

 
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