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Abandoning domestic coil by intentionally drilling hole in it and plugging

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PeachPlantoon12
PeachPlantoon12 Member Posts: 4
edited July 20 in THE MAIN WALL

PSI was constantly creeping up on old Columbia Emerald EM-100 oil fired boiler. Troubleshooting pointed to a pinhole leak in the domestic coil, which is no longer in use. Wanted to just abandon it, but the consensus seems to be either:

a.) Buy a blank plate, which is impossible in my scenario given Columbia is out of business. Tried searching online, can't find a blank plate that would work.

b.) Leave the coil in place but uncapped and open to the air (obviously not possible since its got a pinhole leak and water would just be coming out constantly).

c.) Take the face plate off, cut the coil off, then put the face plate back on and plug it. Hesitant to do this because it disturbs the gasket, and when placing it back, might not seal. Replacement gaskets for this boiler don't seem to exist anymore… so, let sleeping dogs lie…

which brings me to my solution, which I haven't seen suggested anywhere (and im not sure why):

d.) Stick a long drill bit into the inlet and outlet and intentionally drill a hole in the coil (one on each side for redundancy). Then flush the coil to get any shavings out, and cap the coil inlet/outlet with threaded NPT brass plugs.

My understanding is that the concern over capping the coil is pressure build up. Well, if you have a hole in the coil (two 1/8" holes in my case), then that shouldn't be a concern; pressure in the coil will always equalize with the surrounding water jacket.

Am I missing something or is this approach reasonable given the circumstances? Just find it a little odd that in all the posts I've been reading about abandoning coils, no one has suggested this.

Comments

  • pecmsg
    pecmsg Member Posts: 7,359

    cut the lines inside and out.
    plug the fittings!

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 20,634

    If you have water in the boiler and the coil connections are uncapped water will leak out of the coil if it is bad.

    It will not leak if the coil is good.

    If the connections leak then plug them on the outside

    If they don't leak leave them alone

    No need to drill holes or mess with the gasket.

    bjohnhy
  • Jamie Hall
    Jamie Hall Member Posts: 27,617

    This^^^. Or look at it this way. If you already have a leak, there's no need to add another one…

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • HydronicMike
    HydronicMike Member Posts: 390

    A gasket for that boiler/coil is easy to find.
    Drilling holes would work, if it’s even necessary. But keep in mind the coil is…well coiled. So no need for a long drill bit.
    Personally, removing the plate, cut out coil and either put the plate back on with a new gasket and plug the holes, or getting a blank and new gasket are the proper solutions.

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 20,634

    The op states the boiler is old

    If the gasket is not leaking on an old boiler leave as is or you will regret it. Snapped bolts and pitted gasket surfaces are no fun

    PeachPlantoon12
  • PeachPlantoon12
    PeachPlantoon12 Member Posts: 4

    The coil on this boiler is not the spiral type you're thinking of — the coil goes straight back about 14" before curving back toward the inlet (see attached pic for example). I ended up using a 24" drill bit from HF and it worked well enough! As for the gasket, I cant find an exact replacement anywhere online, but feel free to link me.

    Screenshot 2026-07-20 at 10.02.01 PM.png
  • PeachPlantoon12
    PeachPlantoon12 Member Posts: 4

    I ended up going through with drilling holes in the coil. As much as id like to cut the lines inside, that would mean taking the front plate off an old gasket. If it doesn't seal when I put it back, that's a major headache considering I cant find an exact replacement gasket anywhere. Drilling holes in it was easier than taking it apart and should accomplish the same thing I believe

  • PeachPlantoon12
    PeachPlantoon12 Member Posts: 4

    This is what I thought initially, but there's a bunch of conflicting advice in other threads where people said never to cap them

    I suppose maybe it's possible for a pressure buildup if the pinhole leak isn't enough to reduce it quick enough or gets clogged … well in any case I ended up drilling the holes (1/4" each) so I won't have to worry about it!

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 20,634

    @PeachPlantoon12

    Contact TFI-Everhot in the Boston Area

    Tel. 1-617-924-3877

    or ; Sales at TFI Everhot.com

    They make tankless coils for every boiler ever made. If you want a new coil they can make one. They have the drawing for most all boilers.

    If you want just a gasket, I am sure they would have one.

    They make tankless coils for all the boiler MFGs