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Two pipe steam-Main vents

ChrisMc Member Posts: 1
In a 2 pipe steam system, is there ever a reason you would not have a main air vent at the end the steam main?


  • heatboy
    heatboy Member Posts: 1,468
    Is the reteun......

    .....wet or dry?

    There was an error rendering this rich post.

  • Unknown
    edited February 2010
    Two Pipe Steam- Main Venting

    On a 2 pipe system:  2 possibilities -

    1. If the end of the Steam Main terminates in the Wet Return, there needs to be a vent on the end of the main so that the air can escape.

    2. If the end of the Steam Main connects to the Dry Return Main, there needs to be an F& T Trap on the pipe between the two mains. An F&T trap allows air and condensate (water) to pass through the connecting pipe to the dry return but not steam. Air escapes from the steam main by way of the connecting pipe, through the trap, into the dry return and out through a main vent located on the dry return. (see attached diagram)

    - Rod
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