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Geothermal Heat Hillbilly Style

Discussion in 'Heating or Cooling of your AP system.' started by travelbilly, Aug 6, 2013.

  1. travelbilly

    travelbilly Member

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    The frost line here is only 3ft deep or, about a meter. Can't I simply bury 100' or so of 1" PE tubing down there where the earth is a constant 56F/13C and pump me FT water through it? Even if I put a piece of copper or aluminum pipe in the tank as a heat exchanger... I'm thinking that keeping the FT's at 13c, it's going to keep the whole greenhouse warm. People often put huge water tanks in their basements and keep the water warm as water is so thermally stable, it serves to keep their homes warm. Should work, no?
     
  2. Murray

    Murray Site Admin Staff Member

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    Good plan Travelbilly, It is done all the time in your part of the world. Excellent idea. Keep us posted how the project progresses. Many members will be very interested to see how it goes.
     
  3. David - WI

    David - WI Member

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    I would say no, it's not going to be that simple.
    First, the "frost line" means it gets down below 32F at that depth and the water in your tubing will freeze. Second, even if you put it down 6 or 8 feet and the ground was 56F; your fish tank probably wouldn't stay 56F unless you're passing the whole volume of your system several times per hour... like maybe 10 times? Third, supposedly even small amounts of copper in contact with your system water could be toxic to your system. Last (that I can think of) is that your tubing will probably plug up with sludge and/or bio-slime goopy stuff.
     
  4. travelbilly

    travelbilly Member

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    Where I am, one doesn't have to go significantly beyond that line to hit warm dirt. I am concerned about the 2 other things you mentioned: whether copper would harm the fish (does anyone know about aluminum?) And if I pump the FT water straight the line could get clogged. Maybe it could enter that system right after filtration...
     
  5. stretcho

    stretcho Member

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    This is interesting as I'm thinking a similar system. Hadn't thought about the biofilm, and didn't think the energy input would be that high?
    There will be an answer.
     
  6. TonyS

    TonyS Active Member

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    Copper is a no no in aquaponics, but not because of the fish, copper is used in aquariums to treat many fish ailments, the problem with copper in aquaponics is it will kill bacteria (good, bad and ugly, which is why it is good for treating fish) and invertebrate (such as crayfish).

    Aluminum is generally toxic to fish in acidic water, which again prevents its use in aquaponics.
     
  7. Dillon

    Dillon Member

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    Hi TonyS, do you have any references or further reading regarding your comments about Copper and Aluminium in Aquaponics? the reason why I ask is that I have copper components in my four autosiphons in a small test system and there is a healthy slime coating on the copper which to me indicates that it has been colonised with bacteria as the rest of the system surfaces have and I have yet to register a level of copper in the system water above 0, total water volume is around 700L and was established in May this Year.

    Regards
     
  8. Robert123

    Robert123 Active Member

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  9. Robert123

    Robert123 Active Member

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    Go with stainless steel lines is you can afford it. Good heat transfer properties. Resistant to corrosion. No animicrobial properties.
     
  10. David - WI

    David - WI Member

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    http://news.msn.com/science-technology/space-junk-nasas-failed-forgotten-projects#image=2

    I wonder what effect that had on marine life when they all finally settled to earth?
     
  11. Dillon

    Dillon Member

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    Well that was an interesting read and thanks for the link Robert123.

    Not surprisingly, all the tests reported in this article are the results of ‘microorganisms that threaten public health’ and it is apparent that a wide range of microorganisms are killed off almost completely within very short timescales of being in direct contact with copper ions or copper alloy surfaces, the list is extensive and while it does not include the Nitrosomonas and Nitrobacter genus, there isn’t a microorganism listed that is resilient to the effects of contact with copper ions or the touch surfaces of copper alloys.

    Interesting also to note that the relatively low levels of copper ion concentrations to have an effect on the stated tests started at 0.02g/L which extrapolates to 20ppm, the Food Standards Agency in the UK regulates the permissible levels of ionic copper in water supplies to 3ppm and is generally found less than 1ppm.

    So in conclusion, unless you’re considering using an old copper hot water cylinder or calorifier for use in an aquaponic system then, to err on the side of caution, copper is most definitely a no-no but the odd brass valve or piece of copper tube is just insignificant in the production of copper ions and touch surface to have a noticeable effect on the water quality or nitrifying bacteria, I calculated there is a surface area of around 350mm² of copper alloy in a system of around 700L and my readings this morning were still 0 with an API 1-4ppm copper test kit.

    Regards

    P.S. My apologies to Travelbilly for hijacking your Geothermal thread! Whistling
     
  12. David - WI

    David - WI Member

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    But if all of the water in your system is passing through that piece of copper tubing or brass valve 50 or 75 times a day, there's a lot of water contacting that small surface?
     
  13. Dillon

    Dillon Member

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    Agreed, but there’s still not enough copper alloy in the system leeching sufficient ions to affect water quality and as far as the water being in contact with the copper regarding the efficacy of copper alloy touch surfaces, then theoretically this process will help in neutralising any water bound microorganisms affecting human health identified in the article posted by Robert123, the antimicrobial properties of copper.

    Additionally, the population of nitrifying bacteria in an aquaponic system primarily take up residence on the surfaces in contact with the water and very little in the water itself so therefore will not in the main be in contact with the copper component.

    Furthermore, a concern I had regarding the small copper component in the autosiphon has now been allayed, due to the antimicrobial properties of copper it is now less likely to suffer from any microbial build up leading to eventual clogging.

    The more I think about it the less concerned I am about small quantities of copper alloys in my little test system, I shall however continue to test for any developing traces of copper in the water.

    Regards
     
    Last edited: Aug 31, 2013
  14. Robert123

    Robert123 Active Member

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    It is most often the cationic species of the metal that is antimicrobial. Those species can be bound up by lots of things (such as sulfates, etc) and rendered harmless (or at least changed to a lesser active species). It's all going to come down to corrosion and the resulting concentration of copper moved into the water from that corrosion. Most people probably are not circulating water that contains nitrates through their copper drinking water pipes. I will bet you copper nitrate is a pretty strong antimicrobial.

    Now with that said... The antimicrobial properties of copper in your application does not concern me as much as much as the corrosion does. I think you are going to get much better long term heat transfer properties from the stainless due to decreased corrosion. Copper tubing probably has a thin protective anti-corrosive coating on it, but once corrosion starts it will accelerate and foul the tube dramatically. When that happens, your heat transfer coefficient is going to go to poop.
     
  15. Robert123

    Robert123 Active Member

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    I thought this discussion was talking about circulating the water through a copper tube buried in the ground for use in heating water?
     
  16. travelbilly

    travelbilly Member

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    Instead, I ended up sinking two ibc's in the ground. They'll be in a greenhouse and I'll use water heaters if I need to, probably will need to...
     
  17. DOUBLEB

    DOUBLEB New Member

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    I have a system that all of my pipes are underground. This worked pretty good last summer when the temps. were running 105-deg f to 110-deg f my systems high temp. was 80-deg f. I could cover my grow beds with foam insulation and bring it down a little more. This would help in the winter but I use the heat from the water to help heat the tunnels. The temp. this winter which has been the worst we have had in years never got below 35-deg f which is low but survivable. My fill line is about 60' long, the drain from the beds to the sump (the sump tank is underground also) is about 50' and then the return line to the fish tank 60'. I also have a solar water heater but on the best day we have had this year (not very many of them) I can only gain 3-deg f. Deep soil temp. can and does help to maintain the temp.
     

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