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No heat in riser

In a commercial building off of 1 main steam line I am getting no steam up the riser. The pipe runs maybe 250 feet from the valve and the pipe is hot for maybe the first 200 feet than cools off. Checked the return side and have very good vacuume back to the pump and all valves are open. Thanks


  • Pumpguy
    Pumpguy Member Posts: 541
    I would check

    to see if a trap hasn't failed closed.
    Dennis Pataki. Former Service Manager and Heating Pump Product Manager for Nash Engineering Company. Phone: 1-888 853 9963
    Website: www.nashjenningspumps.com

    The first step in solving any problem is TO IDENTIFY THE PROBLEM.
  • Noel
    Noel Member Posts: 177
    I agree

    Break open a union nut at the radiator and see if you have vacuum or pressure at that location. Either way, see if the steam moves while the nut is partly open (loose) to determine why steam and air won't move in that pipe. That will help you locate the direction, relative to the radiator, that the blockage is.
  • engineer84
    engineer84 Member Posts: 2
    1 more question

    Thanks guys. I just put a new trap in maybe 3-4 weeks ago. Could there be too much mud in the drip leg? The building was built in 1908. I am sure they installed new pipes somewhere along the years but who knows 50-60 years ago and I know the bottom of the drip hasn't been cleaned out in decades.

    The radiator gets heat after about 5hrs of the boiler being on around 4lbs.
  • Noel
    Noel Member Posts: 177

    You'll need to blow air through each part of the piping to see where the blockage is. The mud leg is a great first guess, that's why it is there.

    It probably will be a pocket like the mud leg, or a horizontal part of the piping. Vertical pipes don't normally catch debris.
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