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Leaky steam supply valve

benben Member Posts: 66
I have the recessed cast-iron convector shown on pg. 104 in "We got steam heat." The supply valve is leaking from the big nut on the union. The area under the radiator is very tight. I tried using a channel lock plier to loosen the nut but it wouldn't budge. Any suggestion on the type of wrench to use?
Burnham Independence IN8


  • Jamie HallJamie Hall Member Posts: 6,653
    Try to avoid

    anything with teeth on it!  They'll mess up the nut.  A good channel lock, though, should do it OK.

    However, watch out for union nuts.  The old "righty tighty lefty loosey" doesn't always apply the way you think it's going to.  If trying to turn it one way doesn't work, try the other -- sounds obvious, perhaps, and if you've already done that, sorry... but as I say, it's not always obvious which way tightens on a union when you're just looking at it.

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-McClain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • benben Member Posts: 66
    Still unable to

    loosen the big nut on the union using a channel lock. Any other ideas?

    Here's a picture of it.
    Burnham Independence IN8
  • nicholas bonham-carternicholas bonham-carter Member Posts: 6,535
    Loosening the union nut

    Try to find a big open end wrench of the appropriate size at harbor freight, so you have a good grip on the nut. Use a few light hammer taps in both directions to see if it moves.

    Loosening it slightly will enable you to retighten it.

    If it still leaks, then taking the joint apart completely will allow you to wipe the faces clean, and put a little Dawn liquid on them to lubricate them enough to align themselves for a good seal, as you tighten up the nut.--NBC
  • PumpguyPumpguy Member Posts: 272
    I have found

    that a few hammer blows on the union nut itself will allow it to be freed up using a wrench.  It's best to back-up the nut on the opposite side with a heavy piece of metal, like the heel of a pipe wrench.  Don't get carried away with the hammer blows.  This method is also used to break up a cast iron fitting if it can't be loosened up with a wrench. 
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  • benben Member Posts: 66
    Open ended wrench


    What do you mean by open ended wrench. Is it an adjustable wrench. I don't one big enough for the nut will fit in there. Can you give me a URL of the wrench?

    And do you mean regular dawn dish washing detergent?
    Burnham Independence IN8
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