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2 pipe steam fitting

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2pipesteam
2pipesteam Member Posts: 4
in Strictly Steam

Home built in 1900. Two pipe steam with a natural gas boiler. No visible trap on the return side of any radiator. There is one main vent at the boiler on the return line. Each radiator has a Hoffman 1A 1/8” vent opposite the supply/return side of the radiator towards the lower third of the last radiator column. Radiators click and chirp and I’m trying to find the culprit. Radiator is properly leaning toward the return, pipes have space to expand and Contract. I found this fitting underneath the wood floor. Does anyone know what this is? It is on the dry return side of the line of each radiator underneath the floor.

IMG_4439.jpeg

Comments

  • pecmsg
    pecmsg Member Posts: 6,933

    that’s a check valve

    The direction of flow is right to left.

  • 2pipesteam
    2pipesteam Member Posts: 4

    Thank you!

  • mattmia2
    mattmia2 Member Posts: 16,117

    the better question is why?

  • Jamie Hall
    Jamie Hall Member Posts: 27,060

    And the other question is — why are there air vents on the radiators? There shouldn't need to be, if the outlets go into a dry return.

    The maximum cutout pressure for that system should probably be no more than 0.5 psig (8 ounces).

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 19,947

    Someone probably added the rad air vents. Shouldn't need them but I guess they can do no harm.

    Check valve are probably to prevent any steam in the returns from backing into another radiator but it the pressure is where it should be they shouldn't be needed.

  • 2pipesteam
    2pipesteam Member Posts: 4
    edited 4:02AM

    There is only one main vent Hoffman 75h for the whole system. Building is 4 floors with 4 radiators per floor. I think the vents on the radiators are to avoid having to put a vent at the top of the stack to balance the system and have it heat evenly. System is running at .5psig

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