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Cause of heavy corrosion - mystery

I had a new HE boiler installed in 2016 in my home. Since then I've had some troubling corrosion problems. First I noticed on the 110V elec supply (BX cable) the metal sheathing on the cable (Al) is completely dissolved in about a 3 in long section. There is a semi clear goo where the metal cladding had been.
Also have serious corrosion near one of the boiler circulator pumps where steel nipple connects to brass check valve (then another steel nipple and elbow into 1" copper). Saw today that connection at the valve now has a small drip.
One thing I noted inside the boiler (Burnham Alpine 150kBtu) is it looks like the ignition wire to the main igniter was pinched under a flange during construction. I could not move it. Having worked on high voltage systems in a past life, I know stray high voltage can do strange things and if the insulation is slightly compromised I could have voltage leakage.

Any other thoughts on these corrosion issues (and I don't live near a body of salt water)?


  • mattmia2
    mattmia2 Member Posts: 5,517
    Condensate leaking back in to the armored cable.

    Is the nipple leaking slightly or is the system leaking such that it is having makeup water added?
    JUGHNE Member Posts: 9,760
    The ignitor cable, if grounded even somewhat, would not deliver the spark needed to light the burner. And it is only hot when the ignition cycle is active.

    Matt may have the answer with condsate leak, that is quite corrisive to most things except plastic, PVC etc.
  • Derheatmeister
    Derheatmeister Member Posts: 1,280
    edited June 2021
    Could you post some pictures of the areas with the corrosion ?
    Pictures of the System may also help..

  • hot_rod
    hot_rod Member Posts: 16,301
    Also details about what type of heating distribution, is it radiant, radiators, air coils? If any plastic, PEX tubing was used it needs to be hydronic specific with an oxygen barrier.
    Every picture tells a story.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • HomerJSmith
    HomerJSmith Member Posts: 1,562
    What is the water quality in the sys? Anti-freeze? Post some pics.
  • ChrisJ
    ChrisJ Member Posts: 12,836
    "the metal sheathing on the cable (Al) is completely dissolved in about a 3 in long section. There is a semi clear goo where the metal cladding had been."

    Do you have any pictures of this?
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • Sorry posted pics in response to DM. Here they are -- still looking for clues. Regarding the other questions: Boiler serves rad floor; steel wall radiators (runtal new); coil in forced air system. Filtered water filled - no A freeze. Pex Oxy barrier and copper piping. Leak is ~ 1 drop per week.
    Arrow in pic shows pinched ignition wire.

  • mattmia2
    mattmia2 Member Posts: 5,517
    edited September 2021
    It feeds radiant tubing? What kind of tubing? Is it oxygen barrier tubing in the floor itself if it is pex or some other plastic?

    Is there by any chance a leaking form tie in the concrete wall where that mc cable has dissolved, or is or was there flue condensation that was dripping on it?
    EBEBRATT-Ed Member Posts: 11,996
    @mattmia2 makes a good point about a concrete tie.

    Aluminum flex won't deal well with concrete if their is any moisture.

    The other two piping leaks should be fixed, there is a flange right there so it's an easy fix as well as the ignition wire
    HVACNUT Member Posts: 4,592
    While the repair is being done on the strainer, rotate the circulator flanges. The motor should be horizontal. 
    Replace and reroute the B/X cable. That's scary.
    JUGHNE Member Posts: 9,760
    Is that "strainer" actually a swing check valve?
    I see the bolt that might hold the swing gate in place.
    It should remain in the position it is in now.

    But yes the motor shaft should be horizontal.
  • hot_rod
    hot_rod Member Posts: 16,301
    The s as aluminum flex is intake air, I hope?
    the leak at the pump may just be a bad thread connection.

    The check is oversized, too close to the pump, and the wrong type for Hydronics.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream