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Two Pipe System Clarification

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simon_skove
simon_skove Posts: 70
in Strictly Steam

Two pipe steam/vapor system.

I need a refresher.

All things being dandy, boiler makes steam, steam fills the piping system (hopefully without too much loss due to cold pipes). As the steam reaches each radiator through the top valve at one end and fills the radiator, the air escapes through the bottom valve and heads down the dry returns back to the boiler and continues its escape through the large return vents back at the boiler.

There is no visible devise at any radiator to prevent the steam from following the air through all the dry return pipes and out the return main vents back down to the boiler.

This is a 1920's system with virtually no changes other than the boiler and the deletion of radiators. One that was on the ceiling in one of the rooms in the basement and one on the second floor landing.

My question is how did the steam stay in the radiators back when in 1925?

Comments

  • Steamhead
    Steamhead Posts: 18,903

    There are probably orificing devices in the radiator shutoff valves that keep the steam from reaching the rad return connections, as long as the boiler pressure does not exceed 4-8 ounces or so depending on who designed the system.

    Or, there might be devices inside the radiator return elbows that you can't see without disconnecting the radiators. These kept the steam from reaching the dry returns.

    Co-Founder, All Steamed Up, Inc.

    Semi-retired

    Baltimore, MD, USA

  • Jamie Hall
    Jamie Hall Posts: 27,821

    and just to add to @Steamhead 's remark — provided that the orifice or regulating valve is correct, and the steam pressure is kept down where it belongs, all the steam which can get into the radiator is condensed by the radiator before it has a chance to escape. Simple and elegant.

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • 109A_5
    109A_5 Posts: 4,512

    The thing that may be missing is a means to purge the air in the steam main efficiently, I see a water seal which will return any condensate in the main to the dry return but no path for the air. To me burning fuel to push air out of the main through the radiators is not helping with efficiency.

    Purging the air in the main through the radiators may be a comparably slow method. As @Steamhead mentioned the radiator valve and any orifice on the return side of the radiator is used to slow down the flow rate.

    image.png
    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • simon_skove
    simon_skove Posts: 70

    Steamhead - showed you the pictrue above over 10 years ago. Based on the information I provided you determined this was a Tudor System.

  • Steamhead
    Steamhead Posts: 18,903
    https://forum.heatinghelp.com/discussion/comment/1905379#Comment_1905379

    Your memory is better than mine….. Tudor it is.

    Co-Founder, All Steamed Up, Inc.

    Semi-retired

    Baltimore, MD, USA

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