Solar Hot water

Discussion in 'Solar and Geothermal Water Heating Forum' started by Bill Arden, Jul 27, 2008.

  1. Bill Arden

    Bill Arden Computer Programmer

    Messages:
    584
    Location:
    MN, USA
    I picked up two Electric Water Heaters with built in heat exchangers.

    "Vaughn Model S50P Electric Water Heater. 50-Gallon Capacity, Single Heating Element, 30Sq foot heat exchanger.
    http://mustang.hoffhilk.com/maxanet/2008julyme/DSC03311Q.jpg
    http://mustang.hoffhilk.com/maxanet/2008julyme/DSC03313Q.jpg
    http://mustang.hoffhilk.com/maxanet/2008julyme/DSC03744.jpg

    They seem perfect for some sort of solar project.

    I am also wondering if they could act as a boiler and heat the in floor tubing. In kind of a "dual fuel" concept.

    Thoughts?

    Edit: I am guessing these are single wall heat exchangers. I am thinking I should use non-toxic antifreeze on the loop side.
    Last edited: Jul 27, 2008
  2. Mikey

    Mikey Aspiring Old Fart, EE, computer & networking geek

    Messages:
    2,718
    Location:
    Central Florida
    They look great for a solar project in, say, Minnesota :D, where a Glycol loop to the rooftop panel would be advisable. Thinking in reverse, I don't see why you couldn't plumb the heat exchanger side to under-floor heating lines, but the 9kVA element might be a little wimpy for a demanding application. I'm sure that knowing you've got a 30sqft heat exchanger is useful to determine how much heat could be transferred to the load loop at a given temperature differential and flow, but I'm not the man to do the calculation :(.
  3. Bill Arden

    Bill Arden Computer Programmer

    Messages:
    584
    Location:
    MN, USA
    My highly insulated garage was fine last winter with just 3600 watts of baseboard. (900sq, R19 walls, R48 attic, no windows, insulated door)

    I'll get out the calculator after i pick them up today. :)

    It should be able to at least warm the floor since there is 2 inches of foam under the slab.

    I hope they turn out to be a good deal.

    On the other hand even if they leak, the scrap value is probably more than the $50 ea payed for them. (assuming copper heat exchanger)

    I also picked up a 2x3 foot chromed steel sheet for a solar trough experiment.
  4. they wont be very efficinet

    they will not be very effieient if they have heating elements inside the tank....

    if you use them to heat the water only you might
    have a fair system,

    but if you are going to try to heat the floor, your elemnets will run your heat bill sky high...

    I tried that years ago for some condos, and it did not work well...




    also if you run glycol through that heat loop inside the water heater, their is a strong possibilty that you will get your self poisoned some day.......
  5. Heaven Net

    Heaven Net Guest

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  6. Bill Arden

    Bill Arden Computer Programmer

    Messages:
    584
    Location:
    MN, USA
    Ahh yes we have another spammer bringing up dead threads.

    FYI: The heaters in question were destroyed in my garage fire. :(

    As for the post saying that they would be expensive to run. Electric heat is 100% efficient and it would not matter if I heated things this way since all the heat generated would be conserved in the building. The final cost would depend on the off-peak utility rate.
  7. Mikey

    Mikey Aspiring Old Fart, EE, computer & networking geek

    Messages:
    2,718
    Location:
    Central Florida
    Has anyone actually signed up for the off-peak deal in their area? I looked into it seriously enough to track my usage for a week and see how things would have gone had I been on the local (TECO) plan, and the result was that it wasn't worth it. I even looked at using off-peak power to charge a battery bank to provide power during peak times, and found that a) what with conversion inefficiency and investment amortization it wasn't attractive, and b) TECO wouldn't allow it anyway.
  8. Cookie

    Cookie .

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    Mikey, I looked into it once and my results were the same as yours. I came to the conclusion if you want to save money, just don't use any energy. I am very energy conscious out of need and the boys are really good about it, too. We conserve like crazy. I guess at the same time, too doing a good thing for the conservation projects. I did find this though, buying new appliances that were more energy efficient helped, mine were pretty old, the ratings, they weren't even rated, lol, and then, I usually try to run things after 7 pm, because the rates are alittle less then, I don't think it makes a grand difference, but Mikey, you know as well, every little bit helps.

    How's the windows? Did you ever finish them?
  9. Mikey

    Mikey Aspiring Old Fart, EE, computer & networking geek

    Messages:
    2,718
    Location:
    Central Florida
    Very true. I mentioned in another thread that I've been monitoring lots of the "little bits" and discovered that as of yesterday the following little things accounted for the listed percentage of the total electricity consumption:

    Old fridge in the garage -- 12.5%
    New fridge in the kitchen -- 6.3%
    House PC -- 7.2%
    Home theater -- 3.4%
    My office -- 7.5%
    Total -- 37%

    That works out to about $50/month, which was quite a surprise, but we decided that it was all worth it. We could probably save around $6/mo by buying a new fridge for the garage, but the 13+ year payback wasn't compelling.

    Windows are all done, house is tight as a drum, feels warmer/cooler as appropriate, saw no difference in the electric bill. Go figure.
  10. Cookie

    Cookie .

    Messages:
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    Mikey,

    You mean you can't do without that beer in the garage fridge? ;)

    When I said, i replaced my appliances, I mean I needed to replace my appliances, My stove was 29 years old, and I really only replaced it because the oven broke, and the replacements weren't easily found or who knows, I might had kept it. I liked that stove, this one, the cook pots can slip off of which I don't like. I usually have the neighbors and girlfriends kids in here.

    Nothing I owned was energy efficient especially me, :)

    Home theatre, nice.
    Last edited: Jul 11, 2009
  11. Cookie

    Cookie .

    Messages:
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    Mikey,

    One thing I did do, which I know lowered my bill and kept me from having to buy them so often are the flourescent bulbs for the outside. I even bought them for the flood lights and spotlights, and post lights.

    I won't use them inside though because of mercury content.
    One other thing I did do, was to buy smaller room sized air conditioners.
    Last edited: Jul 11, 2009
  12. Bill Arden

    Bill Arden Computer Programmer

    Messages:
    584
    Location:
    MN, USA
    I've had a dual-fuel/off-peak heating system for 14 years. It has been helpful in that I pay less to heat and it also gives me a backup source of heat.

    I've also looked into using large UPS's, however the PUC won't allow it yet. :(

    I did save quite a bit electric when I upgraded my tube monitors to LCD ones. I've also been using CF lights for over a decade and I even have LED spot lights outside.

    I also use a water based cooling system that uses well water to cool the house.
  13. chris8796

    chris8796 New Member

    Messages:
    100
    Location:
    Illinois
    Is this a spray on the roof type system?
  14. Bill Arden

    Bill Arden Computer Programmer

    Messages:
    584
    Location:
    MN, USA
    The ~65F well water is sent threw radiators and then it's sent to a sprinkler on the roof.

    I also run a dehumidifier and window AC units to remove moisture.
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