Does anybody think that the amount of coil that STSS recommends is overkill? 540' of 3/4" copper gives about 15,000 square inches of copper surface area. In another post somebody said that about 4000 square inches was needed for an eko 40. I hope it is overkill because I am planning on using 5600 square inches (3 section of coil in parallel, each one is 100 feet of 1/2" copper). Assuming the STSS numbers are overkill then the cost comparison is closer. I am already committed to copper since I have already bought and coiled a bunch of it, but if I was starting over, I might go with a flat plate. I will have spent about $500 for all of my copper, including fittings, so I am about twice the cost of flat plate.