I just made a dual coil chiller. It was not too hard to put together. Sourcing the parts was probably the most time consuming part.
I have only had a chance to use it once, but it performed amazingly well. I did a 20 minute whirlpool, then turned on the water. It got the temp down to 70 in less than 10 minutes! I use a pump to recirc while I'm chilling. I think that helps a lot.
My website is still a bit of a disaster, but if you want to check out some pics you should be able to see them here.
Noice! Looks very well crafted! I love the detailed breakdown of the U, if I can find the parts, I'm going to do a similar approach. I had thought of doing a simple Y, but I think your U approach will actually lead to potentially less chance of uneven distribution.
I'm curious why you decided to place the U so low? Looks like it would be submerged in the wort, and maybe I'm being paranoid, but the idea of soldered joints being in the wort worries me a bit (don't want heavy metals getting into my brew). Had you considered instead running the 1/2" tubing farther up, and doing the U above the wort-line?
I'm also curious having the two lines interleaved makes much difference? The approach I was going to take was to have two concentric chillers, one at 10" diameter, and one at 8" (or maybe 9" and 7"). I was thinking of using copper wire to both keep it rigid, space out the coils, and keep the two concentric chillers equally spaced from each other.
Also, got any advice on learning how to solder copper? You clearly did a great job, so any advice you can give would be super-helpful.
To answer your question about the direction of flow. Mine introduces the cold water at the top for both coils. I can't say if one way is better than another. My thinking was that the warmest wort is at the top so put the cool water there. Also, running the coils counter to each other might tend to transfer some heat from the 'warm' side of one coil to the 'cold' side of the other coil. If they run in parallel they are more likely to take the heat from the wort and not from each other...I think.
I think I wasn't clear. I agree that having the flow start at the top of the coil, and the return straight up from the bottom makes the most sense. I was more asking if I should have them go opposite directions radially, i.e. the inner one clockwise and the outer one counter-clockwise. Think that would make any difference?
Thanks again for the response!