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Steam question

MJC Member Posts: 8
I'm involved in a steam boiler replacement project for a pumped return system. The existing boiler feed unit is actually a small condensate pump that is not tied into the boiler pump control. I was planning on replacing the condensate pump with a boiler feed pump until I was given the original heating system drawings which showed that the heating system had a vacuum pump. Obviously at some point the original vacuum pump was replaced with a condensate pump. My question is can I still use an appropriately sized boiler feed pump or should I consider installing a vacuum pump since this is how the system was originally intended to operate?


  • First, measure the load on each supply main

    Then check the sizes of the mains against how much steam they need to deliver. Don't forget to add the pickup factor to the radiator load BEFORE checking the pipe size.

    If it can be run without the vacuum, the pipe size will need to be big enough to carry the load.

    Then check the returns, the same way. The returns may not be divided up the same as the supplies, so check to see what each return actually needs to carry.

    If you need a vacuum pump, the piping won't be big enough to run CORRECTLY without one.

    I've seen vacuum pumps on systems that they didn't belong on, as well.

  • Geno_15
    Geno_15 Member Posts: 158

    How old is the system? When someone changes something you always have to wonder. Why was the vac set up changed and did it work before/after? You're wise to question this, lucky you got the plans. Continue your investigation and follow Noels advice. You may find that the system has not been working properly or all areas may not getting heat.
  • MJC
    MJC Member Posts: 8
    The system was installed in 1958.

    No one knows when the condensate pump was first installed. In checking with the owner a lack of heat has never been a problem. Thanks for your help.

  • MJC
    MJC Member Posts: 8
    Thanks for your help Noel.

    I'll start checking pipe sizes.

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