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Equalizing line

Bruce_29
Bruce_29 Member Posts: 9
edited January 2021 in Strictly Steam
Ref a vacuum steam heating system with an equalizing line between the condensate return system and the boiler steam header. Mechanical vacuum pump to generate the vacuum.
Why is the check valve that is installed in the equalizing line in a water loop seal (trapped) below the horizontal line elevation by about 6" of the pipe itself?
I have heard to keep a better seal between the seat and check valve disk, it will remain cleaner then if it was in the steam line as contaminants might be deposited on it, the 6" gives you a differential for proper operation, to prevent the disk from chattering, etc.

Comments

  • Pumpguy
    Pumpguy Member Posts: 632
    The purpose of the check valve in the equalizer line being dropped is to trap some water so the valve seat becomes water sealed.

    Not often seen, but equally effective is a thermostatic radiator trap at the end of the uncovered cooling line where it drops down to the return line.

    See attached illustrations.
    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.
  • Bruce_29
    Bruce_29 Member Posts: 9
    @Pumpguy Were the illustrations you attached from NASH literature and if so is the literature still available?
    So if the check valve was not dropped it would still work but would have more of a tendency to leak?
    Thanks for your input
  • Pumpguy
    Pumpguy Member Posts: 632
    @Bruce_29, yes, most of the literature I have came from Nash. I have most of Nash's engineering and installation drawings. Most are post 1950, but some are earlier.
    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.