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zurn pex brass fittings corroding only on cold water

mikedo
mikedo Member Posts: 228
in Plumbing
working on a job 10 to 15 year old install all pex with zurn fittings blue and red no manufacturer on pipe. its a well all the hot water fittings are good but the cold water are all leaking . I'm going to replace them with plastic but wanted to know if anyone has an idea why this is happening. oil fired water heater with dielectric nipples. thanks mike

Comments

  • mikedo
    mikedo Member Posts: 228
    job is in connecticut fairfield county
  • SWEI
    SWEI Member Posts: 7,356
    edited August 2016
    SWAG:

    A dissolved gas (O2, CO2, H2S and SO2 come to mind) which boils out during the water heating process. Result: Low pH cold water becomes neutral pH hot water.
  • hot_rod
    hot_rod Member Posts: 23,108
    Fittings and tube have appropriate numbers?

    Cold water causes fittings to shrink, hot causes them to expand??

    Also the quality of the crimp. If it has copper crimp rings, and the tools was out of adjustment, it may not have enough"squeeze" The "go, no go" gauge that comes with crimp tools would be a good test of the crimp integrity.

    I have seen tube with out of tolerance ID where the fitting rattles around inside, tough to take that up with a crimp.

    Or import fittings that were out of spec.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • hot_rod
    hot_rod Member Posts: 23,108
    It amazes me just how precarious that seal is when you cut open pex fittings. It seem that just one ridge is all that is holding back the drip on some fittings
    .
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • NY_Rob
    NY_Rob Member Posts: 1,370
    ^ I guess that's why we see the occasional "is it safe to conceal pex fittings?" posts.
    It is kind of scary when you think about it....
  • SWEI
    SWEI Member Posts: 7,356
    F1807 is kinda that way...
  • Jamie Hall
    Jamie Hall Member Posts: 24,560
    Perhaps a very dumb question, but... reflecting on the plumbing it the place I care for... are you sure that they are leaking? The place I care for gets a tremendous amount of condensation on the cold water pipes and fittings. None, of course, on the hot. It doesn't take that much condensation, over the years, to produce surface corrosion deposits.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • mikedo
    mikedo Member Posts: 228
    thanks for the advice I'm going to post some pictures sunday. i don't think its condensation since its been happening for a while but I'm not ruling it out
  • mikedo
    mikedo Member Posts: 228

  • mikedo
    mikedo Member Posts: 228

  • mikedo
    mikedo Member Posts: 228
    got 2 pictures every cold fitting looks the same hot is fine its an oil fired water heater. I'm going to replace them all with plastic fitting but id like to know whats causing it
  • Jamie Hall
    Jamie Hall Member Posts: 24,560
    Yuch. Can't say I've seen the like... but a couple of thoughts. First, if it's every fitting and it's all over them like that, it seems unlikely -- at best -- that it's a leak. Since it is plastic pipe, it's not electrolysis. Also, since it's on the outside, it's not the water quality -- and it's unlikely that the type of water heater has anything to do with it. The water temperature might, though, by causing some condensation (yeah, I know, one track mind), possibly in combination with some air quality factor.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • hot_rod
    hot_rod Member Posts: 23,108
    Certainly looks like they are seeping through the fitting. Could be loose tube, out of tolerance fitting.

    I don't care for those chinch clamps. They were originally designed for automotive use, low pressure and vacumn lines of rubber tube. They tend to egg shape the tube at the fitting, they always feel loose to me.

    Replace the fittings and rings. Chech the water quality also, ph and hardness.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • mikedo
    mikedo Member Posts: 228
    the rust makes me wonder how does brass rust
  • ratio
    ratio Member Posts: 3,774
    What's the RH down there? What's the dew point? What's the groundwater temp? Find those, see if condensation is ruled out. Right out of the gate, only on the cold line sure sounds like a temperature issue.
  • Fred
    Fred Member Posts: 8,542
    mikedo said:

    the rust makes me wonder how does brass rust

    Brass is an alloy. It could well be some chemical reaction causing zinc or other metal to leach out of the brass and rust. No?
  • BobC
    BobC Member Posts: 5,496
    It could well be something in the area attacking the brass but are we certain it really is brass?

    Whenever I buy brass hardware I take a magnet with me so I don't end up with any ferrous brass, More than once I've found boxed hardware, labeled as solid brass, that fails the magnet test.

    Bob
    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • JUGHNE
    JUGHNE Member Posts: 11,262
    You said 10 to 15 years old, so would that rule out that these would be lead free brass fittings? Just a thought.
  • Fred
    Fred Member Posts: 8,542
    edited August 2016
    US Code #42, U.S. Code › Title 42 › Chapter 6A › Subchapter XII › Part B › § 300g–6
    banned lead from use in public and residential potable water installations in 1986. Doesn't seem like its been that long but that is 30 years ago.
    EDIT: Now that I think about it, In 1989, I re-plumbed a house that I was restoring. When I called for an inspection, I had to prove to the inspector that I used lead-free flux on the solder joints. Fortunately, I had all my plumbing supplies/materials still in the house and I was able to pull out the can of flux that clearly said "Lead Free" on the lid. He was satisfied with that.
  • JUGHNE
    JUGHNE Member Posts: 11,262
    Fred, would that have been lead solder.....the typical 50/50?
    It was just a couple years ago that only LF valves/fittings were the only thing available for potable water.

    Now if this was the CA state code, that would be different, everything there comes with a tag that there is a risk.......even lawn darts are thought to be a safety hazard there. ;)
    Solid_Fuel_Man
  • Fred
    Fred Member Posts: 8,542
    Jughne, here is the link: https://www.law.cornell.edu/uscode/text/42/300g-6
    It is the Legal Information Institute, Cornell University. The legislation was US Law and applied to all 50 states. Here is a quote from that document: (b) State enforcement
    (1) Enforcement of prohibition
    The requirements of subsection (a)(1) of this section shall be enforced in all States effective 24 months after June 19, 1986. States shall enforce such requirements through State or local plumbing codes, or such other means of enforcement as the State may determine to be appropriate.
    I did also see a clause that said "no fittings, fixtures, piping shall be sold after 1996" but that appeared to be for non potable water supply.
  • SWEI
    SWEI Member Posts: 7,356
    edited August 2016
    The 1986 definition of "lead-free" included anything with less than 8% lead content. The 2010 definition lowered that to 0.25% lead.
  • Fred
    Fred Member Posts: 8,542
    According to the 1986 document, the definitions for lead free are:
    Definition of lead free
    (1) In general
    For the purposes of this section, the term “lead free” means—
    (A) not containing more than 0.2 percent lead when used with respect to solder and flux; and
    (B) not more than a weighted average of 0.25 percent lead when used with respect to the wetted surfaces of pipes, pipe fittings, plumbing fittings, and fixtures.
  • SWEI
    SWEI Member Posts: 7,356
    edited August 2016
    That's the 2010 language.
    https://www.copper.org/environment/water/sdwa/
  • Fred
    Fred Member Posts: 8,542
    That's what is also in the 1986 document. I just lifted the text right out of that doc.
  • SWEI
    SWEI Member Posts: 7,356
    edited August 2016
    That doc is noted as Current through Pub. L. 114-38 which is dated 2015.

    2010 was a major change -- all the old stuff had to be removed from distribution or marked "for non-potable use only." Many manufacturers re-branded the old "lead free" as "low lead." Aquatherm calls it "industrial brass."
  • Fred
    Fred Member Posts: 8,542
    That explains that! Thanks
  • Hilly
    Hilly Member Posts: 428
    Are you sure they are ZURN fittings?
    http://www.plumbingfittingsettlement.com/Default.aspx
    This could have something to do with it, NO?
  • mikedo
    mikedo Member Posts: 228
    im not sure that they are zurn fittings but the ball valves say zurn on them. I'm going to look at one thats not leaking to see if i can find markings thanks for the info.

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