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Solar water heater

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by Eric Johnson, Mar 6, 2006.

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  1. Eric Johnson

    Eric Johnson Mod Emeritus

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    I don't know if this has anything to do with efficiency either (though I suspect it does), but I've noticed that with the heat exchanger connecting my gas boiler and wood-fired boiler, it's a momentum thing. In other words, it takes longer to get the system up to temp, but once it's there, it tends to hang in there longer. The Achillies heel of that arrangement is that any inefficiencies in your piping and elsewhere in the system (insulation, etc.) are magnified the more times you circulate the same hot water. Plus, the heat differential is less, which is contrary to efficient operation of a heat exchanger, at least as I understand it.

    Life is full of trade-offs, no?

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  2. roac

    roac New Member

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    One of the negatives to glycol circulating in your water supply is... Glycol poisoning if a leak develops! Death?? If it is for summer only why glycol?
  3. fbelec

    fbelec Minister of Fire

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    you use the non toxic type.
    and antifreeze also helps to bring up the boiling point in water. if done right you can bring up the boiling point to 230 - 240 degrees. i had a friend that had a solar hot water system. he had a 80 gal sepco tank. the sepcos are nice they're made for solar with electric backup and the tanks are stone lined. if the sun was down and you used alot of hot water just let the tank sit a few and the stone would bring up the water temp. anyway his system would heat that tank up so hot that the pressure relief valve would blow off. and the temp coming down off the collectors was running 225 degrees. so if i were to make up a solar water system i would use glycol
  4. Eric Johnson

    Eric Johnson Mod Emeritus

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    roac: I use non-toxic heating system glycol in my wood-fired boiler system. I don't want my family to go blind. The reason for glycol in a solar water heater would be "just in case." I assume the solar collector would work in the early spring and late fall and possibly even at times during the winter, so I think having glycol in there would extend the heating season, if you will. Even though it was zero this morning, it's around 25 outside right now and the sun is really beating down.

    I didn't know that about the boiling point, fbelec. That plus any pressure in the system. I'd be really happy if I got hot water over 150 out of the arrangement. If you got something approaching 200, I'd think it would make sense to add storage capacity.

    I checked around on the internet last night and you can get an assembled solar panel for between $500 and $700, which the mfg. claims can heat enough hot water for 3 or 4 adults. I've got two adults and one female teenager, so my needs are probably closer to those of 4 adults. But that's not bad. Doing the work myself and scrounging up the rest of the components, I bet we could do the deal for less than $1,500. I don't know about the payback time, but I bet it would add more than $1,500 to the value of my house.
  5. roac

    roac New Member

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    Ah!! Non toxic. Duh!! Just remembered they make non toxic stuff for the car too.
  6. carpniels

    carpniels Minister of Fire

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    Hi Eric,

    in my youth, I worked in Cyprus for 6 months. It is in the mediterranean, and gets nice and hot. I had a penthouse with a solar waterheater on the roof. It worked fantastic. I went up there regularly to take a look at how it worked so I know it quite well.

    If you plan on only running your system in the summer, I can draw you a nice simple water solar heater system that will be very good, easy to maintain and cost very little.

    Let me know

    Carpniels

    PS. If you ever need a hand for a few hours, write me and I will help. Rome is only 15 minutes from Clinton.
  7. Eric Johnson

    Eric Johnson Mod Emeritus

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    Thanks Carpneils. Somebody said you were in Holland. Have a nice trip?

    Day like today, I think solar water heat would work great, even in this climate.

    I'm still researching this thing, including any NYS or Fed tax incentives, but I'll let you know if I need the drawing and/or your help.

    --Eric
  8. roac

    roac New Member

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    Don't forget utility rebates. I dug up this article that says you could get 40-70% of your costs paid back.

    http://moneycentral.msn.com/content/Savinganddebt/Savemoney/P126521.asp
  9. joshuaviktor

    joshuaviktor New Member

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    Eric,

    Where did you find the collectors for 5-700? Just curious.

    Thanks,

    Joshua

    P.S. For simplicity's sake, think about PV powered pump. It speeds up the more sunlight it gets, so it is almost automatically at correct circulation. As for using present heat exchanger in water heater, do it! Just plumb some valves in so you don't LOSE heat to solar collector in winter, when hot water is roaring through there, from boiler. And add PRV's, if you add valves, yada yada, you know the drill. However, to be really efficient, think about getting one of those old 60 gallon or so broken but well insulated water heaters, and piping both the boiler and solar collector into it with separate heat exchangers. Solar runs all the time, year round, as long as it has hotter water than the tank. Wood runs as long as you're burning. The tank gets piped before the intake of your gas water heater tank (or switch to tankless), and therefore becomes a serious storage device, without pulling off btu's from radiators. Just a thought.
  10. cbrodsky

    cbrodsky Member

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    In New York State, you can get fantastic rebates - you can take a tax credit of 25% of the cost of the system, and after that, there is a new Federal incentive for 2006 that allows a 30% rebate on what is left. It is important to realize this is not a deduction, but an actual credit directly off income tax due.

    There are caps on these but they are designed to generally cover a professionally installed system. The net of this is that you buy the system for 100*0.75*0.7 = 52.5% of your actual cost. For that price, I would certainly buy profesisonal grade equipment, and may very well pay for the install too. Search on the web to get more details.

    The only downside (not often publicized) is that AMT disallows these deductions if it applies to you. Hopefully Congress is going to fix that this session. The original intent was to make these incentives exempt from AMT.

    I think a solar hot water system with rebates is the perfect complement to wood heating to really drive down annual energy costs.

    -Colin
  11. Eric Johnson

    Eric Johnson Mod Emeritus

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    EDIT: Thank you, NY Soapstone. I did all this research on the internet tonight, only to come back here to find out you had somehow sneaked the information past me. That 25% is has a new ceiling of $5,000 in NYS. I won't come close to that. And there's even a sales tax exemption on the gear--both state and in some cases, local as well. Not sure if my time/labor can be included somehow, but even if it's just hardware, that is, as you said, a fantastic deal. And I agree: no point in skimping on the technology if more than half is going to come back in my tax refund. And so far, for better or worse, I'm not a victim of the AMT.

    raoc,

    Thanks for that link, man. I like that 30% federal tax CREDIT. That would make a big difference. I've almost got my wife talked into the idea before any tax incentives.

    josh,

    I think you're right about the extra tank. That way, with a little piping and some valves, I can keep the two separate and use them to complement each other. I also think the PV-powered pump is a great idea. With glycol and a dedicated storage tank, you could maybe even run the thing in the winter. Here's the link to one of the more expensive panel assemblies I found online. There are others closer to $500.

    http://king-solar.com/catalog/mfg/radcoproducts/410php.html

    I also found a couple of used units on Ebay but both were pick-ups located in Oregon and Florida.
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