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Boiler over filling

Ok I am trying to troubleshoot a boiler . The system shut off when I went to check the glass tube it was completely filled with sediment.  I cleaned it and flushed the system and reset the water level after a day or so the lwco was buzzing very loud the boiler shutdown and the water level was high. I drained the system again and cleaned the probe. Reset the system again and a couple days later same problem . Im thinking the relay in the lwco is bad and not shutting off the auto feed system . So I was going to order a new lwco and replace it . Does this seem like it is the issue or could it be something else . 


  • Big Ed_4
    Big Ed_4 Member Posts: 2,687
    I would first shut off the auto feeder . And check with an electrical multi meter first before throwing money at it ...
    I have enough experience to know , that I dont know it all
  • nizmo111
    nizmo111 Member Posts: 2
    Do you mean test the lwco with tester . Sorry these boiler are pretty new to me.  I am a asc mechanic so im pretty good at running down electrical problems just not a 100% on how to test it 
  • Turn off the valve feeding the auto-fill, and see if the water level does not rise.
    Sometimes the valve will be leaking because of foreign particles on the seat, or over pressure will force water out into the wet return, temporarily causing a low water situation, and subsequent refilling. When the boiler is off, and the condensate returns, the boiler is then overfilled.
    Alternatively, a leak from a hot water coil can overfill the boiler.—NBC
  • Jamie Hall
    Jamie Hall Member Posts: 22,887
    At some risk of pointing out the obvious... that LWCO which is buzzing is... the LWCO. Which is an essential safety device. If there is a suggestion that it is malfunctioning, unless you have a second, backup LWCO, the boiler is not safe to run until you find out why -- unless someone is there, watching the sight glass while it runs.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • MikeL_2
    MikeL_2 Member Posts: 481
    Is it possible you have a bypass manual feed valve that is leaking & overfilling the boiler?
    JUGHNE Member Posts: 11,021
    When you cleaned the sight glass did you brush into the boiler on the isolation valves ports of the sight glass. If the glass was that dirty there is a good chance that the ports are somewhat plugged and give you a false reading in the glass.
    EBEBRATT-Ed Member Posts: 15,297
    The buzzing is probably the 101 feeder solenoid. I would take the low water cutoff apart and clean it or replace it. The float may have a hole in it. Make sure the pipe connections are clear.

    And as @Big Ed_4 said troubleshoot it don't just by parts.

    This is an Important safety control.

    Hire a pro if you need to