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WTGO COIL Leak

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Robert_H
Robert_H Member Posts: 349

GotGot called and for another problem on this boiler. But noticed the evidence of leaking from the coil area. I was initially thinking that someone just didn't do the follow-up tightening, all these bolts seem to be tight. But looking at it it looks like the gaskets not installed but I can't imagine that water wouldn't be spraying out everywhere if the gasket wasn't installed. What do you think?

The nuts are tight.

1000009398.jpg 1000009397.jpg

Comments

  • mattmia2
    mattmia2 Member Posts: 17,762

    someone might have made their own gasket such that it doesn't stick out or used permatex or gasket shellac.

    Robert_H
  • Robert_H
    Robert_H Member Posts: 349

    That wouldn't surprise me. as you can see from the PEX they took a lot of short cuts. There are no isolation valves at all to do any supply side work I have to secure the house supply…

  • pecmsg
    pecmsg Member Posts: 7,383

    tighten the bolts?

  • Jamie Hall
    Jamie Hall Member Posts: 27,651

    There should be some sort of gasket there, although it might be thin. Sort of off topic, but did they even use the correct bolts? I've always liked to have three threads visible — but that is automotive and aircraft, so maybe it's OK here?

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    Robert_H
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 20,721

    There is only one way to find out. Hopefully the face of the boiler casting is not damaged.

    Robert_H
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 12,602
    edited July 14

    I’m not a fan of that installer. Whoever connected the flexible tubing directly to a 90° adapter, without providing any practical way to service the coil, did a very poor job.

    I doubt there is even a mixing valve of any type installed on that tankless coil. If you want to do right by the customer, you may want to show them the manufacturer’s instructions for connecting the domestic hot-water piping. You could then quote a price for replacing the gasket and reconnecting the piping properly, including the installation of a mixing valve.

    EDIT:

    This is from the instruction manual regarding how to connect the potable water piping. I have added some valves in color and also painted the mixing valve green in order to understand and see it easier. That part is not included with the boiler and must be purchased separately, and installed as indicated in the instruction manual.

    Screenshot 2026-07-13 at 10.21.20 PM.png

    This information is on page 23 of this manual: Weil McLain WTGO boiler.

    Here are the photos of 2 boilers with a visible red rubber gasket. the factory often uses a black rubber gasket that is a little thinner.

    image.png

    I like it when the copper piping is connected directly to the tankless coil, with enough support for the mixing valve.

    The problem I have with using a 90° male-to-copper adapter is that you may not be able to tighten the threads sufficiently while still having the copper leave the coil in the desired direction. That often leads to leakage at the threaded joint. It may not produce visible water droplets because the water evaporates, leaving behind a crusty mineral buildup.

    You may need to use plenty of pipe dope and Teflon tape, and perhaps even some lampwick, to seal the joint while positioning the pipe in the proper direction. After you place the service valves and mixing valve in the proper orientation, you can connect flexible hot and cold water tubing away from the boiler.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

    Robert_H
  • pecmsg
    pecmsg Member Posts: 7,383

    Then remove everything, clean the faces, install new gasket. Tighten a few times over several days weeks.

    Neverseize helps

    Robert_H
  • Robert_H
    Robert_H Member Posts: 349

    Yes, It was pretty much a hack job. There is a mixing valve but its hanging on pex and no isolation valves.

  • pecmsg
    pecmsg Member Posts: 7,383

    so redo it properly

  • Robert_H
    Robert_H Member Posts: 349

    Yes, that's the plan. She's got a handful of problems in that basement and I'm taking care of them in order of seriousness and under the constraints of her budget.

  • Robert_H
    Robert_H Member Posts: 349

    Update,

    TheThe homeowner agreed to me replacing the gasket and repiping the system correctly. And does anyone know why the replacement gasket is $91. It's a 7-in round gasket with a big hole in the middle and six bolt holes I can't imagine what they're making it out of to make it worth $91.

  • mattmia2
    mattmia2 Member Posts: 17,762

    some of those craft printers are good at cutting sheet gasket. most head gaskets don't cost that much.

    Robert_H
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 20,721

    $91 LOL.

    The gasket cost $.50

    Shipping from China $90.50

    Robert_H
  • pecmsg
    pecmsg Member Posts: 7,383
    edited July 20
  • Robert_H
    Robert_H Member Posts: 349
    edited July 20

    Sorry all, I was just so flabbergasted. I needed someplace to yell about it

  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 12,602
    edited July 23

    Who are you purchasing it from? https://www.supplyhouse.com/Weil-McLain-590-317-550-Heater-Gasket

    Here is an overpriced gasket that is much less than your price.

    Oops. that is the tankless coil for the steam boilers that WM has available. I will do more research for the round gasket.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

    Robert_H
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 20,721

    I would try TFI Everhot

    Robert_H
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 12,602

    TFI does not sell direct to the consumer. You must buy from a wholesale supply of some kind. the part number is "GOW gasket" or "DHTGOW Gasket" TFI and or Everhot are brands of Diversified Heat Transfer. That gasket needs to be special ordered. To save on shipping you can have the supply company do a Drop Ship direct to your address. It should fit in a large envelope and go USPS

    OR

    You can always just grab a blank piece of gasket material and make one yourself with this stuff: Red Rubber Gasket

    Screenshot 2026-07-23 at 2.17.01 PM.png

    I have sucessfully done that more than once. Cuts easily woth large scissors. To make a hole for the bolt you can use a piece of 3/8" OD or 1/2" OD copper pipe and a hammer.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

    Robert_H
  • 109A_5
    109A_5 Member Posts: 4,293

    If you want to make your own paper gaskets, gasket paper can be found at most auto-parts stores.

    I like the Silicone rubber and have used it and in my case it is reusable. I would get it in the closest thickness as the original gasket. In the example above 0.12" seems a bit thick. Silicone rubber cuts easily with an X-Acto knife.

    image.png
    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
    Robert_H
  • mattmia2
    mattmia2 Member Posts: 17,762

    a hole punch for paper is good for making smaller bolt holes too.

  • 109A_5
    109A_5 Member Posts: 4,293

    Kind of wondering if that boiler uses this gasket type, O-ring with a square cross section. If you knew the size maybe McMaster-Carr, although at that diameter the choices get slim.

    image.png image.png
    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 20,721

    I used to use 1/4" or 3/8" or 1/2" pipe nipple with the end sharpened to punch bolt holes. I know a lot of guys use red rubber but after a while it dries out and cracks

    Robert_H
  • mattmia2
    mattmia2 Member Posts: 17,762

    epdm is the thing to use for water with disinfectant.

    if t is a square o-ring you can buy cord stock and super glue the end together.

    Robert_H
  • Robert_H
    Robert_H Member Posts: 349

    If they are using an o-ring type gasket and it's in a recess that would explain why I can't see a gasket even if it's there.

    EdTheHeaterMan