Stevehull, where did you find the SEER ratings on those marine units? I never could locate them.
Amazing what being sick can do for project planning, I just saw randens heat exchanger here
http://ecorenovator.org/forum/geothe...-pressure.html and thought of a much cheaper heat exchanger than I previously proposed.
PEX on the outside, copper on the inside, use drilled pex plugs soldered to the evaporator line to keep the water side leaks away, and a simple T to feed/ remove bayou water from the heat exchanger. PEX is about 1/4 the price per foot, so I could run a much longer heat exchanger for the same $ if my selection is correct, I could make them for about $2/ ft, so 25-50 feet would not be out of the question. That said, with 1/4" refrigeration tube(my guess on stock size) a 25 ft exchanger would only have 1.6 square feet of exchange surface.