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Cold only leak?

danmayer175
danmayer175 Member Posts: 60
in Strictly Steam

Has anyone ever seen a leak that only appears when boiler is cold? I had the boiler off for a day and found a damp spot on floor below tankless connection. Never happens with boiler in use. Is it possible some joint stays sealed when metal's hot but leaks cold? Or tiny trickles that evaporate in use but drip when cold? You can see rust trails under tankless on right of photo with remnants of damp on slab below.

PXL_20250226_113141920.jpg

Homeowner in Middletown, PA

1936 house with 1996 Burnham V74 oil-fired 1-pipe system

Comments

  • psb75
    psb75 Member Posts: 1,017

    Hot metal swells/expands. Colder metal shrinks. Generally that is the case with most materials. Gasket under the tankless coil plate? Start spraying or soaking the bolts on the plate with penetrating oil in preparation for removal.

    GGrossBobC
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 17,466

    probably the tankless heater gasket. It is common for them to leak when cold as the gasket gets old it loses it elasticity.

    Long Beach Ed
  • bmma
    bmma Member Posts: 38

    My boiler (a 36ish year old Weil-McLain) did that. It didn't show signs of leaking when it was cold out and the boiler was running more often, but on the warmer days when it was going longer between heating cycles I started to see some water on the floor. I had it replaced shortly thereafter.

  • Big Ed_4
    Big Ed_4 Member Posts: 3,148

    I like the stud and brass nut system for coils some manufactures use ..

    There was an error rendering this rich post.

    CLamb
  • techforlife
    techforlife Member Posts: 120

    From the stains on the mud leg connections, I think you should plan on boiler replacement.

  • danmayer175
    danmayer175 Member Posts: 60
    https://forum.heatinghelp.com/discussion/comment/1845819#Comment_1845819

    I was wondering about that. There are flaky scales of rust at those joints. Sounds like that's not normal?

    Homeowner in Middletown, PA

    1936 house with 1996 Burnham V74 oil-fired 1-pipe system

  • techforlife
    techforlife Member Posts: 120

    It is only normal for a boiler that is well on the way out.

  • danmayer175
    danmayer175 Member Posts: 60

    More clues found. The bright red stuff is some sort of sealant applied over the gasket edges. I suspect an attempt to seal it up when it leaked years ago. Sealant is mostly separating now and peels off easily.

    image.png

    Another shot of rust at section joints below. Anyone care to hazard a guess on life expectancy? Should I abandon all hope of lasting another heating season? @Steamhead

    image.png

    Homeowner in Middletown, PA

    1936 house with 1996 Burnham V74 oil-fired 1-pipe system

  • 109A_5
    109A_5 Member Posts: 2,285

    Some Burnhams don't have a good track record, but if it was mine, I'd let it cool down and flood it to see where it is leaking from. I'm real curious about things like that.

    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System

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