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One-pipe steam trap ??????

Working  on a Steam boiler.  First of the season in Kansas city. This is a one-pipe system, But at each radiator at the location were the air bleed should be  there is a small  1/8 " steam trap. that is piped back to the boiler. The house is 1920's The boiler was replaced in 1998. The Original call was the boiler is over filling. I pulled and cleaned the low-water sensor and flushed the heat exchanger. Than cycled the boiler by the electrical service switch. to see if it would overflow during shut down. The reason  I tested it like this, I could not get the pressure switch @ 1psi to satisfy. I think it may be the traps not closings. Than at shutdown the  boiler is flooding due to the traps are finally opening  after some time and releasing the condensates in the radiator  

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 19,884
    sounds like...

    a KMC, or some similar system which used air lines like that (and often controlled the radiators through restrictions on the air lines).  These things do go back to the boiler -- but they have to have an air/vacuum release where they get to the boiler.  Look and see what you can find.  It is possible that when the boiler was installed (yeah, I know, 10 years ago, but...) something was changed that hadn't ought to have been... 



    That is... if it is a KMC or something of the sort, there really shouldn't be a trap, even a tiny one, at the radiator, unless it opens reliably on air or vacuum (in which case, it's more like a vent...).



    One way or another, there has to be a way for air to get out of the system when it fires, and to get back in when it quits. 
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Steamhead
    Steamhead Member Posts: 15,636
    That's an "air-line" system

    also known as the Paul system, after Andrew Paul, who brought it to market.



    In the old days there was probably a vacuum exhauster that sucked all the air from the system thru those air lines. That made the system very quick to heat, and allowed it to make steam at lower temperatures.



    Where do those air lines end? If they're tied into the boiler somehow, that may be the problem.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • sraburne
    sraburne Member Posts: 15
    thanks

    Thanks for the information. I saw the drawing of the KMC on the posting below yours. Their may have been some parts of the system removed during the new boiler install.  I should have taken a picture of the unit.
  • sraburne
    sraburne Member Posts: 15
    Thanks

    Yea It look like the same system, but with some parts missing. The piping from the trap goes directly in to the wet return. Their is one other different, at the radiator in the drawing  the air bleed looks like  adjustable valve, the one I have looks like a steam trap.  thanks again I should have taken pictures.
  • sraburne
    sraburne Member Posts: 15
    thanks

    All the pipes connect together, than connect into the wet return below the boiler. If the piping is called the wet return on a one-pipe system. you guys have been great thanks  
  • Steamhead
    Steamhead Member Posts: 15,636
    There's your problem

    If those air pipes connect to a wet return, the connection point is filled with water and the air can't vent!
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
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