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  1. #1
    Join Date
    Dec 2009
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    17

    Default pin holes in copper pipe

    I have a client that is suffering from re-occurring pin holes in the hot water re-circ line. house is 15 years old. water comes from a Municipal supplier. The loop is run in the attic the first hole happened in the attic with a small flood in the kitchen in Oct. One hole each month since near the water heater. He is not sleeping well worrying about flooding, If copper is superior to other alternatives why only a 15 year life span.My suggestion is to replace the loop with PEX an put the re-circ pump on a timer, could this be caused by electrolysis or?

    thanks for the help
    Bret

  2. #2
    Join Date
    Aug 2007
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    Dallas, Texas
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    839

    Default Re: pin holes in copper pipe

    delete dumb answer
    Last edited by John B; 01-04-2010 at 08:19 AM.

  3. #3
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    Default Re: pin holes in copper pipe

    Had this same thing happen. Copper is just as good as anything, depending on your water and how you operate the line.
    There are a number of ways to get copper to fail, since you're not on a well we can throw pH out right away. Your two leading likely issues are calcium scrubbing if you have hard water, and too high flow rate whether the water is hard or soft.
    I think I learned all this at the Copper Development Association at copper.org, if I recall.
    Copper forms an oxide layer that stops further loss of the copper into the water.
    But, if you have sufficient flow rates, you can scrub the protective layer off. Do that enough and you're through the pipe. High temps, high solids, high flow rates contribute.
    The solution(s) are to slow the water down with a proper size pump and/or valve it down; also use a timer to run it only when needed; turn down the water temp; and use type L or even K copper.
    Read up on Pex before you use it for a recirc line. It has its own issues in a municipal system with chlorine treated water.
    Good luck

  4. #4
    Join Date
    Jun 2004
    Location
    Martinez, California
    Posts
    14,881

    Default Re: pin holes in copper pipe

    If you've got chlorinated water in your municipal system, don't use PEX, you may have a lower grade copper like Type M, use Type L. This from a representative of the PEX industry .
    “It is not an endlessly expanding list of rights —the “right” to an education; the “right” to health care; the “right” to food and housing. That is not freedom. That is dependency. Those are not rights. Those are the rations of slavery – hay and a barn for human cattle.” - Alexis de Tocqueville

  5. #5
    Join Date
    Jul 2006
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    Portland, OR
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    2,444

    Default Re: pin holes in copper pipe

    In the construction defect world, this was often due to failure to ream connections. The roughness created turbulence (actually, cavitation) in the water just downstream from the connections. Reason is that the oxides never got a chance to form. Always showed up in HW recirc lines first, since that water was alway moving

  6. #6
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    Default Re: pin holes in copper pipe

    Any rough spot can supposedly cause turbulent flow that scrubs the protection off. The line where I had the problem, the holes were just past the elbows, which is characteristic. They have a lot of warnings about cleaning flux and not using too much solder.

  7. #7
    Join Date
    Feb 2008
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    North Central Vermont
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    Default Re: pin holes in copper pipe

    Quote Originally Posted by 1Bivvv View Post
    could this be caused by electrolysis or?
    You mean galvanic action. Electrolysis is for desalinization or hair removal.

    Steel clips or fasteners in contact with copper pipe can cause pin holes, whether through oxidation or abrasion.

    But, if the pin-holes are occuring elsewhere, then the culprits are likely what has been suggested (it is not high disolved solids, though, that's a problem, but low dissolved solids or ionic water softeners).

    The easiest way to lower water velocity is to up-size to 3/4" pipe.
    Last edited by Riversong; 01-03-2010 at 05:24 PM.
    Robert Riversong
    Master HouseWright

  8. #8
    Join Date
    Dec 2005
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    Michigan
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    Default Re: pin holes in copper pipe

    Quote Originally Posted by Riversong View Post
    You mean galvanic action. Yes, particularly if there are any steel clips or fasteners in contact with the copper.
    Wrong. Copper and steel, the steel gets corroded. Not the copper.

  9. #9
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    Feb 2008
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    North Central Vermont
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    Default Re: pin holes in copper pipe

    Quote Originally Posted by dgbldr View Post
    Wrong. Copper and steel, the steel gets corroded. Not the copper.
    In cases of dissimilar pipe components, yes. But I've seen steel fasteners in pipe hangers put pin-holes in copper pipe.

    The reactions in air are not necessarily the same as with the water as electrolyte.
    Robert Riversong
    Master HouseWright

  10. #10
    Join Date
    Oct 2007
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    Southern California
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    2,184

    Default Re: pin holes in copper pipe

    Quote Originally Posted by Riversong View Post
    The easiest way to lower water velocity is to up-size to 3/4" pipe.
    Upsize a recirc line? That isn't environmentally friendly.... And unneeded.

    What type of copper was used? What is the make/model of the recirc pump? Bet it is oversized for the application. Don't need much flow on a recirc line.

    The Taco Model 006 Cartridge Circulator flows 0-10 GPM, which is fine. Add either the mechanical or electronic timer and the temp sensor, so it only runs in the AM and PM when people are using hot water and only runs until the return water is hot, then shuts off. Shouldn't have any scrubbing with that configuration.
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  11. #11
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    Default Re: pin holes in copper pipe

    Calcium scrubbing is from high dissolved solids. Though that may be aiscredited theory. I can't seem to find any info on the phenomenon now, but ten years ago I found web sites listing it as a cause for degradation of recirc lines--that hard water under flow conditions was worse than soft water.

  12. #12
    Join Date
    Feb 2008
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    North Central Vermont
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    Default Re: pin holes in copper pipe

    http://www.allergybuyersclub.com/learning/copper.html

    "Factors causing corrosion include acidity (low pH), high temperature, low total dissolved solids (TDS) content and high amounts of dissolved oxygen or carbon dioxide. Generally, naturally soft water is more corrosive than hard water because it is more acidic and has low TDS. Observations have shown increased copper levels in water softened with ion exchange water softeners."

    "If the water is not corrosive, hard water minerals are slowly deposited on the interior of plumbing. These hard water deposits form a calcium carbonate lining inside pipes and fittings which protects against copper contamination, however, it may take up to five years for an effective calcium carbonate lining to form and softening hard water with an ion exchange unit can either prevent or dissolve the calcium carbonate scale, reducing or eliminating its protective effect."
    Robert Riversong
    Master HouseWright

  13. #13
    Join Date
    Jun 2004
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    Northern Vermont
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    1,381

    Default Re: pin holes in copper pipe

    I wrote an article about this problem for JLC about 10 years ago. The article, "When Copper Goes Bad," is still relevant and is posted free online. Here it is:
    http://www.jlconline.com/cgi-local/v...170a32100a060d

  14. #14
    Join Date
    Aug 2004
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    WV, Cold Climate w/ wind, HDD 7136, 56" avg. precip.
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    402

    Default Re: pin holes in copper pipe

    Zurn instructs not to use their product w/ recirculating systems w/ chlorine levels more than 2 ppm and not to use in closed systems with more than 4 ppm. Both of those numbers are swimming pool treatment numbers and EPA regulates a maximum level of 4 ppm in potable water, so I was surprised to see the results of the Cal Pex. studies about chlorinated water at levels at .5 ppm.

    The UV effects have always made me wonder why Pex isn't packaged in a UV protective packaging. Why don't they package that stuff in a cardboard box?

    If copper might have mysterious failures and if Pex is not recommendable with municipal water systems that are chlorinated then what is the best type of potable plumbing to use with aggressive water? What about ABS and/or CPVC?

    What type of plumbing are you guys using in circumstances w/ aggressive water, in recirculating systems, or just in general?

  15. #15
    Join Date
    Oct 2007
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    Southern California
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    2,184

    Default Re: pin holes in copper pipe

    Copper. Avoid the thin stuff. Don't bury. Debur. Use the right flux. Clean exterior flux off. Flush well. Use one size larger pipe. Avoid contact with other metals. Don't use as a ground except as required by electrical code. No Chinese drywall. Have the water tested, just for the record.
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