Phil wrote: "Think about it--on demand heaters are pervasive in Europe and most Europeans think Americans are nuts for keeping 80 gallons of water at a constant 140 degrees using electricity." Well I agree about the instant hot water idea - we always has them on British boats and in fact in our kitchen at home - however I don't recall ever seeing a 80 gallon tank - either at home or on a boat! Of course the other side of the coin is that the heat exchanger HW tanks use nothing when underway, or for that matter when running the generator to charge at anchor. I find my 12 gal hot water tank stays warm even overnight after a days running. Ron Barr Lady Brookhaven Hatteras LRC 42 Presently lying RI Yacht Club, Narragansett Bay, RI KB1LFX