I wanted to use an immersion cooler so that cold break debris was not put into the fermenter, and also so the main body of the hot wort got cooled quickly and saved hop oils evaporating.
The coil array displaces about 1 imperial gallon, and the reason it is 96 ft long is that over here, 1/2" copper pipe comes in 15 metre lengths. Each 15 metre length made three 5 metre cooling coils. I bought three lengths, and I made 9 coils, giving me 1 practice attempt during the bending phase, as I was intending to use 8 coils. I have only ended up using 6 coils. 5 metres is about 16 ft, so 6 x 16 is 96
I am now wondering if I can make up two more coils out of 5 metre 3kW heater element, and thus make 2 coil shaped heatsticks! I would then re-mount the 6 cooling coils and the 2 heatsticks as an array of eight, fitted to a new lid. i.e. six cooling coils and two 3 kW heatstick coils. This depends on how much straight 5 metre 3kW elements are to buy. The company I am dealing with are not giving me a price for straight elements until I give the full spec on my requirements, which I will do over the Xmas break.
They are saying that the recommended length for an 8 mm diameter 3Kw element in wort is about 2.2 metres ( 7ft 3" ) to give a watt density of 35 watts per square inch. they quote an ideal wpsi range of 30 to 40 for wort.
If these elements are out of my price range I will fall back to plan "B" which is standard 3 kW elements from immersion heaters at 1.270 metres long, at £18 each