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2 pipe heating issues

Alex_17 Member Posts: 1
I am trying to take on a issue on the building i work in and its starting to turn me gray lol.

We have 2 firetube boilers and 2 pumps in the boiler room and if i run the boilers at 10-12psi and at pump pressure will be about 25-28psi i will actually make a vaccum on my main return line. if i bring the boiler pressure to 20 the the head pressure will be 38-40 psi and the return problem goes away. but eh real issue is i have heating issues throughout the building. If i go into any of the wings and drain the return system with a garden hose the system picks up heat very nicelyclose it then it drops down.

I trully think i have a starving problem where we are supplying water but its not returning fast enough via a clog or restricition. Is there any advice.


  • Brad White_203
    Brad White_203 Member Posts: 506
    Sounds like

    you are pumping toward your expansion tank, rather than the only right method, pumping away from your expansion tank.

    What do you think?

    The issue is text-book classic from what you are saying.

    The point where the expansion tank connects is the point at which the system pressure will not change.

    The pumps only want to create a certain difference in pressure. Ideally, this wants to be on the discharge side of themselves.

    If you pump AWAY from the expansion tanks, essentially all of the pumps' energy will go toward making a positive pressure on their discharge sides. Because the expansion tank connection point will not change it's pressure, the discharge has to.

    Reverse this: If you are pumping TO a point whose pressure will not change, then all of the pump energy (it will not be denied!) HAS to be on the suction side. That means a negative number. In your case, below atmosphere.

    All heck breaks loose, the system loses moral authority and starts hanging around with loose women, gambling and alcohol. So much you have noticed :)
  • oil-2-4-6-gas
    oil-2-4-6-gas Member Posts: 641

    how about a picture of the piping //// --pumping to the expansion tank is a problem that is most noticeable in systems with larger pumps,how old is the system ? is this the first season //you may have other problems - --i have been doing commercial heating for almost 20 years now and i have only seen 2 commercial systems that had the pumps piped wrong
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