When I sold my 3 vessel keggle system, I sold the chiller(s) with it. It was basically two chillers that I split flow between, and it worked fine. Now I have a Brewzilla, which came with an immersion chiller, but I don't find that it is very affective. I think I want to make a custom 3 pass unit out of copper, and use the stainless coil as a pre-chiller in the warmer months. I do have some ideas, but I am curious to see what the resourceful DIY'ers here have come up with. Thinking about something like this.