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Water loss

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I have a customer that has 3-300 HP boilers with a 2 pipe steam system. All of the condensate is returned to a boiler feed tank where the only common connection between the three boilers is on the steam supply to a main header. The problem I have is when draining 1 boiler the boiler next to it looses water rather quickly and locking out on the manual reset LWCO. Also after correcting a problem with the burner modulation circuit where the burner was only firing in low, I put the burner back into auto and when it went to high fire the same thing happened with rapid water loss.
The 3 supply’s do enter the main header at the top and the traps at the ends of the header lift the condensate about 3 feet to get back to the boiler feed tank. The bottom of the main header is about 6” above the water line of the boiler.

Comments

  • Intplm.
    Intplm. Member Posts: 2,795

    Hmm. Seems the two boilers are acting as one when draining. Is the condensate return tank working properly? Is the float and pump adjusted correctly?

  • Jamie Hall
    Jamie Hall Member Posts: 26,679

    Are there individual check valves on the feed lines from the condensate tank boiler feed pumps to the boilers? Are they working?

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 19,172

    I would like to see the return piping. Connecting multiple boilers together below the water line (without a check valve(s)) is against code.

    If your feedwater piping from the pumps to each individual boiler two check valves are required by the ASME code. 1 at the feed water pump and 1 at the boiler.

    Those checks are probably bad unless you have some improper piping going on