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tankless gaskets

Paul_69 Member Posts: 251
when i do tankless gaskets and use silicone that comes with tankless or if i use regular silicone it always stretches out and the bolt holes start to slide out and the gasket just expands. they don't leak as the gasket must still be tight on the inside. i have even let the silicone skin and set for a bit but it still slides out. years ago i used to do them without silicone and don't remember this going on. anybody ever run into this situation? is there something i am missing? it would be nice to hear what other techs.have to say. i am almost ready to go back to not using any silicone. as i said they have not leaked but they are moving out to much and don't like whats happening. thx.


  • billtwocase
    billtwocase Member Posts: 2,385
    I don't

    use the silicone. It does allow the gasket to slide, and not tighten. It may not always leak, but I think the chances are better that it will leak with silicone
  • icesailor
    icesailor Member Posts: 7,265
    Tankless Gaskets:

    I have to ask, is the boiler block machined for a square cut O-Ring like a Weil-McLain WGO and you are using a red rubber flat gasket? Because if you are using a flat gasket on the O-ring set up, you are wrong. And what I go through to get the proper O-Ring so I know.
  • Paul_69
    Paul_69 Member Posts: 251

    i am talking about normal tless gaskets. not o ring type. flat surface and round or square.like i said with silicone they squish out when tightening. for years i used nothing but they ship that silicone with coils and i thought it might help inperfections of  boiler coil plate. thanks for replys.
  • Jack
    Jack Member Posts: 1,047
    Silicone is a band-aid

    in this case. given that you were able to do this for so long without the silidope I'd keep doing what you had always done before. A good clean bearing surface is the key and then securing in the proper sequence.
  • Wayne M. Lawrence
    Wayne M. Lawrence Member Posts: 19
    No silicone

    Hi, I too made that mistake once of using silicone when replacing a tankless coil gasket. I now replace the gasket dry, and if the mating surface is damaged I use JB weld epoxy to build up the void, let it set, file it flush, and reinstall the coil. I also use anti-sieze on the bolt, or stud threads to make future repairs easier.
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