Electrolosis between galvanized and copper.

Discussion in 'General Plumbing Help' started by brit, Jan 5, 2012.

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  1. Jan 5, 2012 #1

    brit

    brit

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    Many years ago I added a extra bed room with bathroom. This extension was plumed with copper. The existing house was galvanized. To connect the two together the building inspector told me to use a 6" bronze pipe between the copper and galvanized connection. 15 years later the galvanized connector is showing signs of corrosion ( hot water side ) the cold water side is still OK. I was looking to eventually re-plum with PEX but because there is indirect sunlight under the house apparently PEX may not work without completely covering the plastic pipe.

    So the question I want to know is if I replace the bronze pipe with a small PVC pipe. This is on the hot water side and will not be potable just for showers. Will that be a long term problem. The copper is still grounded via the cold water side, will I need to run a jumper to ground the hot water copper side against electrolysis.

    Thanks Brit
     
  2. Jan 5, 2012 #2

    havasu

    havasu

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    Why not use a dielectric union? After all, that is what they were designed for.
     
  3. Jan 5, 2012 #3

    johnjh2o

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    PVC pipe is not rated to be used for hot water.

    John
     
  4. Jan 6, 2012 #4

    LiQuId

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    use a dialectric like havasu has said, john is right about the pvc and you should be aware that they do in fact make uv stabalized pex so sunlight direct or in direct is not an issue.
     
  5. Jan 6, 2012 #5

    Chris

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    CPVC Pipe is made for hot tho.
     
  6. Jan 6, 2012 #6

    brit

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    Thanks everybody,
    I am beginning to wonder why the local building inspector told me to use the bronze pipe. I vaguely remember him saying something about the plastic insulator in the dielectric union breaking down with age. He was old school back then.

    Any suggestion on what PEX manufacturer has UV resistant pipe. My local Lowes has Vanguard pipe connectors and tools and is convenient.

    Brit
     
  7. Jan 7, 2012 #7

    LiQuId

    LiQuId

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    But no plumber I know actually likes this material for potablle :p
     
  8. Jan 7, 2012 #8

    LiQuId

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  9. Jan 8, 2012 #9

    Chris

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    I don't like it for anything.:)
     
  10. Jan 9, 2012 #10

    johnjh2o

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    I agree with you both. I think CPVC will be proven as a bad choice for potable water. We see it being used quite a bit in my area. But when cutting into hot water line of CPVC that has been in service the pipe is so brittle that you can't use PVC cutters on it for fear of it snapping, you have to use a hacksaw. When it hasn't been in service for any length of time it's fine. Are homes down here are on slabs and it's being used under the slabs with fittings. I fear that after time we will be seeing it fail do to it expanding from the hot water with no way to move at the branches. Causing the brittle pipe to crack. PEX may be a better choice.

    John
     
  11. Jan 9, 2012 #11

    phishfood

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    John, I personally have very little experience with PEX.

    But I have worked for a couple of plumbing shops that had used PEX in the past, but switched to CPVC because of pipe failure with PEX.

    Although I would assume that CPVC can and does fail, I have yet to run across that. Since I have mainly been involved with new construction, I don't have a lot of service experience to make an informed opinion on which is the better pipe. And perhaps I am partial to CPVC because that is what I am used to using. There are ways to shorten the life of CPVC piping systems by faulty installation. For instance, the expansion that you mention can be protected against by installing the piping with offsets to allow for the expansion and contraction. Also, using too much cement on the inside of the fittings will introduce cement to the inside of the pipe and fittings, and that will weaken it. I wipe off the excess on the outside, and am careful with how much gets inside.

    I would be interested to hear what others have seen in the way of failures with CPVC, particularly those heavily involved in the service side of things.

    Not trying to start a disagreement, rather, a dixcussion where we can all learn.
     
  12. Jan 9, 2012 #12

    johnjh2o

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    There were some failures with PEX. It came from one manufacture that no longer makes the pipe. (large company making many plumbing products) We had some of there pipe fail on us. That was some time ago. As far as CPVC goes I read somewhere that they didn't recommend it for recirculation lines. That I have seen. Some of the most brittle CPVC I have run into was on one of those lines. As far as failures under the slabs, we use a leak detection company to find slab leaks for us. Although I haven't seen any myself I have asked this company if they are seeing any. His answer is they are becoming more common. So your guess is as good as mine as to what we should be using.

    John
     
    Last edited: Jan 9, 2012
  13. Jan 9, 2012 #13

    LiQuId

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    I have seen few if any pex failures. there were lots with polly-b. the few pex failures i have seen were not due to the pipe itself but rather the fitting's and of those the most common failure was the brass fittings due to them being inconsistant in their thickness and shearing off, we use only the plastic or kevlar fittings on those lines now. CPVC... ahhh I do hate this material for all but condensate drains, I have seen it fail in the way that john describes, becoming brittle and thin walled over time. I have seen it fail under stress and have also seen it fail when somehow it completely sheared a 90 degree fitting off, possiblly due to expansion and contraction.

    the pex made by Wirsbo is mint, it warantes all its material against defect AND any thing damaged due to a material failure of its pipe AND fittings ( if you use the Wirsbo joining method.. I am unsure if it also carrys its warranty when Pex crimp fittings are used But I believe it does if you are using the Swagelock style crimp fittings ( we never use Copper crimp rings anymore regardless )

    IF you cannot find uv stable pex in your area try to order online or, failing that just get a box of foam pipe insulation and insulate the pipe... bam, problem solved.
     
  14. Apr 16, 2012 #14

    polkplumbing

    polkplumbing

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    PEX pipe is all that I use anywhere. CPVC pipe is rated for hot water but, it MUST be installed correctly. Not wiping the joints can lead to the CPVC pipe becoming soft & balooning until it burts. I have seen this many many times.

    The PEX pipe that I use it NOT clear, Blue or Red. It is 3 layers, white coating on the outside to prevent UV damage over time. A black layer that provides structural support for the piping second. Then a final layer inside the pipe to prevent degradation due to clorhine that most municipal water supplies use as an additive to kill bacteria.

    BowPEX is the pipe. I use it with Brass fittings & the Zinc Copper alloy crimp rings & 1/4 turn ball valves/stops(angle valves).

    When running the piping on a north facing wall or in a space where sunlight does not wear on it insulation is really not needed. However, I use black armaflex type (A/C type) insulation whereever there is a possibility of exposure to UV.

    There are several Pro's to using this type of plumbing system. The piping is practically freeze proof. It a has a memory element when bending. Less fittings & joints are neeeded because of the superior flexibilty compared to PVC, CPVC, COPPER, Etcetera. The fittings do NOT require dry time & can be tested as soon as it is crimped. The fitting to pipe joints can be moved/rotated in relation to eachother at any time while the system is live (after being crimped), without any possible leaking. It is much faster & easier to install. IMO that type of PEX is the best thing going.

    www.polkplumbing.com
     

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