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steam boiler water issue

I have a weil-mclain steam boiler. During the night it tried to cycle on but would shut down before it fired because the low water shut off would light up.  The water feed light also blinked on but no water was added. I'm assuming because the unit cycled off.  The sight glass indicates the boiler is full(water to the top of the glass). Any suggestions.


  • RreyRrey Member Posts: 18
    Id start by cleaning the probe

    If the unit is shutting down before it fires, theres no change in water level.Id bet that that LWCO probe is mucked up. Pull and check the probe and clean it. Sounds like youre getting intermittent contact through the probe, especially if theres actually plenty of water in the boiler.

    If youre knowledgeable, you might jump uot the LWCO to see if it stays on. Dont leave it jumped out, not even while you run to get a new one. It could cost you a boiler.
  • RreyRrey Member Posts: 18

    Also make sure the valves are open at the top and bottom of the sight glass, otherwise the only water in the boiler could be the sight glass....

    Depending on the model feeder you have, there could be a time delay before filling starts, or a valve could be off feeding it.
  • nicholas bonham-carternicholas bonham-carter Member Posts: 6,540
    edited December 2013
    Baulky boiler

    Drain some water out of the boiler, so that the sight glass shows the proper mid-point level, and see if it will start. Valve off the auto-feed, and observe the water level for an hour or two.

    What may have happened is the pressuretrol allowing the pressure to rise, and forcing the water into the reurns. With most of the water in the returns, the LWCO triggers the auto/over fill, adding more water to the boiler. In several cycles , the system can have an over supply of water.

    This over-filling can result in enough water pressure on the pressuretrol to trip it's switch preventing the boiler from firing.--NBC
  • augie69augie69 Member Posts: 2
    steam boiler water issues

    I drained the boiler.  Water looks pretty clean. Sight glass still looks full. Autofill went through 4 cycles and then stopped. Nothing else happened.  Red light on autofill. Really have no idea how much oil may be in the fire box
  • SteveSteve Member Posts: 234
    Auto feeder

    Sounds like the auto feeder is malfunctioning and over filling the boiler. I would disconnect it and drain the boiler until the correct water level is set. Constantly adding water speeds corrosion in the boiler.
  • JStarJStar Member Posts: 2,668

    If you drain the boiler and the glass is still full, then the glass gauge is dirty. But, that's only one problem. Sounds like the LWCO or water feeder have an issue, too.
    - Joe Starosielec
    [email protected]
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