Solar Water Heating System Value

Q: I know that's what you said. Nevertheless, http://www.fsec.ucf.edu/solar/apps/sdhw/dhwsave.htm says it IS what families use.

A: However your maintenance estimates are probably a bit optimistic. Circulations pumps can and do fail. Some can go the 20 years other don't I see no reason why this would not be broadly similar to CH pump reliability. So let's say 50% of system will need one new pump within the 20 years. The comparator electronics, I imagine these would be similar to the reliability of say a an electronic time switch? Anyway: It looks like the answer to my original question is A few hundred quid system should pay for itself. Differing systems and differing usage patterns and requirements make a BIG difference in the decision. Being prepared to wait for the HW is a big help whereas always wanting instant HW works against the solar methods. Sure, and you can figure out how much total water the townies use from municipal records, but you still don't know how much the well-users pump, and you don't know how much of any of that is heated, but everything points to that being pretty well normal. I would think my use is lower than most - if for no better reason than I have to quit showering when the 10gal tank goes cold - but that still means we use well over 20gal of hot water daily, for only two people. At a guess, we could probably do a 100% sampling of this newsgroup, and get a significantly lower usage than 50gal/day for a family of four. But then, we're the people who care about such things...

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