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Pin hole in coil every 17 months. Need help

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Home owner hear . Dont know much about heating so bare with me.

3 years ago i had a contractor install a wm gold oil furnace in my house . ( tankless coil system. ) 17 months later coil has pin hole. It was under warranty so he replaced it. We added a preasure reducing valve since pressure in house was reading 90psi. Sure enough almoast 17 months later same thing is going on . Diagnosed as another pin hole in new coil. Contractor wants to install indirect hot water heater now and block off coil. Im no expert but doesnt that have a coil aswell ? Dont want to waist the money if its just masking a bigger issue. Any ideas out there ?
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Comments

  • Jamie Hall
    Jamie Hall Member Posts: 23,454
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    Before you decide to replace the coil (again) or put in an indirect (which does have a coil, but different metals), get your water tested. I expect you will find something amiss there -- pH too low, chlorides too high (maybe both) are good candidates, but something in the water is corroding those coils.

    And, I might add, all the other plumbing in the house as well.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    kcoppdelta TZman
  • dscolastico07
    dscolastico07 Member Posts: 17
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    Thank you for the reaponse .. the rest of the plumbing in house is original to 1963 execpt for the fixtures .. Do you think it matters what fixture i get the sample from?
  • DanHolohan
    DanHolohan Member, Moderator, Administrator Posts: 16,549
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    Where are you located?
    Retired and loving it.
  • dscolastico07
    dscolastico07 Member Posts: 17
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    Southern Newhampshire
  • HVACNUT
    HVACNUT Member Posts: 5,865
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    City or well water?
  • dscolastico07
    dscolastico07 Member Posts: 17
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    I understand what you guys are saying about the water but i would think other houses on my street would have problems as well. Ive asked people on my street , they have high pressure like i use to but no problems.
  • dscolastico07
    dscolastico07 Member Posts: 17
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    City water
  • DanHolohan
    DanHolohan Member, Moderator, Administrator Posts: 16,549
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    Has anyone from Weil-McLain looked into this? I think they would want to know about your situation, especially since you're posting on this site, which has an enormous readership.

    The rep in your area: https://contractorsupplymagazine.com/pages/News---20141029-SRGI-named-Weil-McLain-reps-in-New-England.php
    Retired and loving it.
  • dscolastico07
    dscolastico07 Member Posts: 17
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    I asked if they would cover the second one under warranty but they denied it .. but i never asked them to actually look into issue .
  • dscolastico07
    dscolastico07 Member Posts: 17
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    Maybe ill contact them to pick there brain . Thank you guys for all the info
  • kcopp
    kcopp Member Posts: 4,443
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    So what would happen? The boiler would over pressurize? Relief valve start dripping? Tell us more about your Heating system... Did the contractor mention where the leak was... from the hot water side into the boiler or the heating side into the hot water?
    I am wondering if something in your heating system is causing the water pH to be off.
    Zman
  • dscolastico07
    dscolastico07 Member Posts: 17
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    Added a picture of system. Pressure goes up and releaf valve opens and overflows cup on the left side of picture . Ive been bleeding off pressure every morning before work so i dont get water on floor .
  • dscolastico07
    dscolastico07 Member Posts: 17
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    He had me get the pressure down to 20 psi then close a valve for 24 hours thats on the right side of picture . By shutting the valve i didnt have hot water for the night but the pressure did not climb ..he said by doing this, it give him enough info to say its a pin hole again .
    Zman
  • Jamie Hall
    Jamie Hall Member Posts: 23,454
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    To go back to your comment on your interaction with Weil-McClain -- perhaps if you approached them from the point of view of "this is happening. Can you help me figure out why" rather than "this happened. Where's my warranty claim?" you might get farther.

    I agree that it might be some aspect of your boiler water chemistry, rather than you drinking water chemistry. But it is the chemistry of one or the other which is the problem.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    DZoro
  • dscolastico07
    dscolastico07 Member Posts: 17
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    Yes i will try that .thanks
  • Grallert
    Grallert Member Posts: 665
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    Which valve did you close? the one up above or the one down by coil?
    Miss Hall's School service mechanic, greenhouse manager,teacher and dog walker
  • mattmia2
    mattmia2 Member Posts: 9,753
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    Which relief is seeping, the one with the solo cup or the one with the deli tray?
  • Jellis
    Jellis Member Posts: 228
    edited January 2020
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    Hi @dscolastico07
    Is there an expansion tank for your Domestic water? I Only see the one expansion tank for your heating loop in the picture.
  • dscolastico07
    dscolastico07 Member Posts: 17
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    I closed lower yellow ball valve on right hand side of picture . And its the relief valve with the deli tray that leaks when pressure gets too high .. Today my wife found an interesting coversation on the town page . People have been talking about having to replace there coil every year for the last 5 years due to pin holes. They said with enough complaining the town will pay for things like coils and pressure valves sometimes. Im taking a sample of the water and sending it out to get tested. Also put in a call to the water department ..wish me luck
  • motoguy128
    motoguy128 Member Posts: 393
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    > @Jellis said:
    > Hi @dscolastico07
    > Is there an expansion tank for your Domestic water? I Only see the one expansion tank for your heating loop in the picture.

    Some water systems have started installing back flow at the curb so residents may need a domestic expansion tank depending partly on the material, distance and size of the water service.
  • JUGHNE
    JUGHNE Member Posts: 11,077
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    If it were city water eating up copper, then it seems all house copper lines would be at risk.
    One difference is that the coil is submerged in old boiler water on the other side of the coil tubing, which would have different chemistry by now.
    Also if high pressure giving high velocity thru perhaps only 1/2" coil could cause early erosion?
    And maybe pressure build up if back flow device is in the cold circuit without DHW expansion tank.
    Just a WAG on my part.

    IIRC, you can get an indirect with stainless steel coil inside, if it comes down to your city water being the bad guy and not hungry for SS.
  • kcopp
    kcopp Member Posts: 4,443
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    I would ask the town what they are using for disinfecting the water… Some town no longer use Chlorine but are now using chloramines and that is more corrosive.
    I am in Dover, NH
    I have seen a couple towns water be pretty nasty.
    Rochester and Exeter especially...
  • dscolastico07
    dscolastico07 Member Posts: 17
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    UPDATE. A local plumber in town on the town page is saying he is fixing coils in town and its not the water. He is adding dielectric unions to the coils due to electrolysis caused by people grounding wires to water main. I just looked i have multiple ground wires coming off the water main. I may try this take the gamble.
    kcopp
  • Solid_Fuel_Man
    Solid_Fuel_Man Member Posts: 2,646
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    Grounding to the water main is code. Electrolysis happens when an electric current is generated from two dissimilar metals in physical contact with an electrolyte (water) present. The power company's neutral (ground) is also connected to that same wire going to the water main. Best thing to eliminate the possibility of electrolysis on a domestic coil is to put a #4 or larger copper wire between the hot and cold. But I dont think that is your problem, unless you have a more serious grounding issue in the house, which most likely would show up other places as well.

    The coil is copper, most likely brazed at the factory to brass connections where you have copper pipe attached. Copper and brass (an alloy of copper) are very similar metals. I'm going to go out on a limb and say that electrolysis is not the problem.

    Your lab results will tell more of the story.
    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!
    mattmia2HVACNUTCanuckerSuperTech
  • psb75
    psb75 Member Posts: 845
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    How about a close examination of one of many of these coils with pinhole leaks? Cut one open and look at both inside and outside of the pipe at the site of a pinhole. A decent metallurgist or chemist should be able to render an opinion.
    Solid_Fuel_Man
  • mattmia2
    mattmia2 Member Posts: 9,753
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    Find the reports from the water utility on their testing for compliance with the lead and copper rule. Unless something specifically heat related is going on, they will probably be seeing a lot of copper or lead in their testing, maybe under the action level, but probably close.
  • HomerJSmith
    HomerJSmith Member Posts: 2,468
    edited January 2020
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    I bet you have electrical current flowing thru your sys water. Check all grounding on the water pipes etc. Put dielectric couplings on the cold water input and hot water output of the tankless heater. Boiler water chemistry is important. You might want to try Rhomar 922 additive in your boiler water.

    Do you have a water softener?
    mattmia2
  • dscolastico07
    dscolastico07 Member Posts: 17
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    This picture is the water test for 2017 . Dont know if it will help since a lot can chage in 3 years but the new one hasent come out yet. Still going to get water tested anyways and maybe compare the two.
  • Solid_Fuel_Man
    Solid_Fuel_Man Member Posts: 2,646
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    Dielectric unions just end up leaking. The brass to copper connection is not an issue. If you "have power flowing" through the pipes, the domestic coil isnt what will pinhole from it.

    Electrolysis is much misunderstood. Poor (unfavorable) water to copper is what causes pinholes in copper. The elevated temperatures 24/7 in the coil may speed up the deterioration.
    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!
    mattmia2Canuckerrwhtg
  • lchmb
    lchmb Member Posts: 2,997
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    If it were my house I would be done with the coil, make the boiler cold start and pipe in the indirect. Use a tank with a lifetime warranty and add dialectric unions to it. You'll start paying yourself back on oil day one..

    Solid_Fuel_ManSuperTechethicalpaul
  • mattmia2
    mattmia2 Member Posts: 9,753
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    I think i'd figure out the water chemistry before shelling out for the indirect. Bad water chemistry will void the warranty on those too.

    Unless you can find a nonferrous dielectric union I would not use them. I suppose you could always use a section of propex if you were paranoid.
    rwhtg
  • dscolastico07
    dscolastico07 Member Posts: 17
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    All good info thanks guys. Just curious . If i went with a indirect water heater with stainless internals, could this still happen?
  • mattmia2
    mattmia2 Member Posts: 9,753
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    Yes, depending on water chemistry and the type of stainless.
  • dscolastico07
    dscolastico07 Member Posts: 17
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    Ok
  • mattmia2
    mattmia2 Member Posts: 9,753
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    The coils in many indirects are not stainless as well so if your water is attacking copper that especially won't help you.
  • Solid_Fuel_Man
    Solid_Fuel_Man Member Posts: 2,646
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    Your water chemistry will determine if it will play better with stainless. In some cases an enameled, aka glass lined, tank will last longer.
    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!
  • dscolastico07
    dscolastico07 Member Posts: 17
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    IF electrical current attacking the coil is in fact the problem. What is the long term fix. Remove whats grounded to pipe except earth ground?
  • Solid_Fuel_Man
    Solid_Fuel_Man Member Posts: 2,646
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    The boiler is iron, connected through multiple copper pipes to the water main, which by definition is grounded.

    This isnt a new house piped with PEX. The boiler is grounded by its water pipes alone.

    Forced electrolysis wouldn't attack just the domestic coil.
    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!
  • HomerJSmith
    HomerJSmith Member Posts: 2,468
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    What I do with dielectric unions is to throw away the EPDM rubber gaskets and I use Caleffi fiber washers that I wet before I install them in the union. I have never had a leak.
  • dscolastico07
    dscolastico07 Member Posts: 17
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    Im having a electrician friend come by next week end and see if we can rule out any stray electricity. Also still trying to get to the lab and drop off my water sample. Thanks for every ones input and ill keep you guys updated .
    Solid_Fuel_Man