Things That Go Drip In The Night, Or The Economics Of A Solar Water Heater

Q: this has been discussed here before, mostly because I expected this thing to crap the bed years ago, but every time I got close to replacing it suddenly my floor was dry for another year or so. I have an indirect solar water heater in my basement, and I think it has, for real this time, reached the end of its useful life. My inner greenie says, of course, to replace it, but I'm not thinking that that is really an economically good idea... my gas bills even in the winter are never over $200 a month; in the summer it's practically nothing. Even on a sunny summer day the output temp. of the solar never seems to get over 85-90F (very shady lot) in the winter I wonder if it even helps at all. There's no controller on the thing just a time switch running a pump so I wonder if on a cold, overcast day if the darn thing isn't sucking heat out of my water supply and dumping it into the atmosphere :/ I remember doing research into this a year or two ago and found that the tank alone would run me over a kilobuck. For that price, when you figure in installation as well (I could probably handle it, if I knew how to charge the loop between the tank and the collector, but I doubt I actually *would*) as well as an electronic controller with tank and collector thermocouples (seems the only way to really make it work efficiently) I don't see a reasonable payoff period... probably by the time it'd paid itself off the tank would again be 20 years old and near death. Am I wrong...? I'm tempted to rip it out, take the tank to the dump, and put the rest of the setup on craigslist as "haul it away! Use it for whatever the hell you want, I don't care!"

A: 1) buy new 40-gallon electric water heater appx. the same size as solar one (which is obviously just a modified electric anyway) 2) remove shell from old one, save copper coil wrapped around tank, discard rest 3) disassemble new tank, slip coil over tank, reinstall shell, fill space between with lots of Great Stuff(tm) (or just stuff old fiberglass back in there) Laugh maniacally at having just spent $400+ on something and immediately voided the warranty. 4) install my "new" indirect solar tank what do you think the odds are that a brand new Rheem 40 gal. tank (the internal tank, that is) is the exact same size as a 20 year old one? seems a lot of mucking about for not much benefit, still... Solar DHW heating is one of the most cost effective solar things you can do. There are various federal tax credits you can take advantage of as well as usually local credits as well. Please elaborate on how this is cost effective...? I'd handwave $3K minimum to replace this thing (like I said, the tank alone, without installation and delivery, seems to run around $1400;) even if my gas bills went up 50% (which I doubt that they would, I don't think it's really doing that much) I'd still be money ahead to just demo it and be done with it. Seriously, I'm not trying to be argumentative, I just am trying to run the numbers here, but AFAICT the benefit is not there. I suppose I could bypass it and watch my gas bill for a couple months and compare it to last year's bill before making any final decisions, but I'm guessing I will only see an incremental increase if anything.

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