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  1. #1
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    Geothermal DX Systems That Use Copper Tubing

    Can someone tell me which Geothermal heat pump systems use copper tubing instead of polyethelene? The key requirement here is to greatly reduce the amount of trenching or well digging that needs to be done.

  2. #2
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  3. #3
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    Quote Originally Posted by inf_sys View Post
    I wonder couldn't you design a copper pipe system for a well that is shaped like a slinky, coiling the the tubing all the way down? That should let you fit about 1000 linear feet of piping into a single 100 foot well. If a non-copper tubing geothermal design requires 500 feet of tubing for each ton of cooling, a copper based one might need only about 200 feet. A five ton system that requires 200 feet of tubing for each ton could end up fitting all the tubing into a single 100 foot well.

    That's still a chunk of change, but it starts to approach a level that a normal human being can consider.

  4. #4
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    Quote Originally Posted by westes View Post
    Can someone tell me which Geothermal heat pump systems use copper tubing instead of polyethelene? The key requirement here is to greatly reduce the amount of trenching or well digging that needs to be done.
    http://www.nordicghp.com/mg/

    Then click on 'Manuals' or 'Products', then 'DX'.

    Best DX machines I ever seen...

    SR

  5. #5
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    Isn't copper only used in direct expansion geothermal systems? With water loop systems, are we not committed to how much ground contact we have?
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  6. #6
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    Moved to residential geo forum.
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    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  7. #7
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    Pacific NW
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    re: copper tubing instead of polyethelene

    May have misread it, but the implication in the OP is that the better thermal conductivity of Cu vs. PE will allow shorter fields.

    Not so. The pipe wall thermal impedance is trivial compared to film coefficients, earth contact, reynolds numbers, etc...

  8. #8
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    Jun 2009
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    Quote Originally Posted by junkhound View Post
    re: copper tubing instead of polyethelene

    May have misread it, but the implication in the OP is that the better thermal conductivity of Cu vs. PE will allow shorter fields.

    Not so. The pipe wall thermal impedance is trivial compared to film coefficients, earth contact, reynolds numbers, etc...
    You might be right, but what you are saying here directly contradicts pages on the web sites of almost every Geothermal DX product manufactured. For example, NORDIC makes this point:

    " 'DX' systems can be installed in a more confined area than a conventional groundloop system, primarily because the heat exchanger coil is much more efficient at transferring heat to the refrigerant than a plastic earth exchanger. Normal loop lengths for a 'DX' machine are nominally 350’ per ton as opposed to 450’ to 500’ per ton for a plastic earth exchanger. Similarly, vertical systems require only a 3” bore hole to a normal depth of 120’ per ton."

    You can find that on this page:

    http://www.nordicghp.com/mg/nordicJu...DX_series.html

  9. #9
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    Jan 2005
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    DX all copper,diagonal or horizontal:

    http://www.earthlinked.com/
    Do not attempt vast projects with
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  10. #10
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    Quote Originally Posted by westes View Post
    ... If a non-copper tubing geothermal design requires 500 feet of tubing for each ton of cooling, a copper based one might need only about 200 feet. A five ton system that requires 200 feet of tubing for each ton could end up fitting all the tubing into a single 100 foot well.

    ...
    Not an expert, but a geo contractor told me recently that the temp in the wells goes up into the 90's over the summer. Can one 100' well accept all of that heat and still have enough temp difference for the geo system to remain efficient for AC?

    Same question for removing heat from the well during the heating season. I believe the contractor told me that the well temp can get quite low in the winter. Will there be enough heat in this small well to provide heating?

  11. #11
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    Jul 2006
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    If you want to take the chance and dig it yourself then i would say go for it.
    Otherwise even with an anode it would not be cost effective to have it installed.
    Copper tubing is easily affected by electrolysis , imagine the headache of finding and repairing verses just replacing sections of loop verses replacing the loop again.
    Just my opinion.
    Let me put it this way, if i could be convinced on this forum it would work i would do it myself.
    You sure are cocky for a starving pilgrim.

  12. #12
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    I just put a call in to them, i want to find out myself.
    You sure are cocky for a starving pilgrim.

  13. #13
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    Jun 2009
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    Quote Originally Posted by jerryd_2008 View Post
    Not an expert, but a geo contractor told me recently that the temp in the wells goes up into the 90's over the summer. Can one 100' well accept all of that heat and still have enough temp difference for the geo system to remain efficient for AC?

    Same question for removing heat from the well during the heating season. I believe the contractor told me that the well temp can get quite low in the winter. Will there be enough heat in this small well to provide heating?
    Probably you are right. The NORDIC system has an interesting feature that they start and stop different loops for just this reason. Their controller senses when a loop is too hot and switches over to use a different loop that is cooled down. Their approach has the additional advantage that when you are in heating mode they use a smaller number of loops and the unused loops become your storage for the refrigerant.

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