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Water level fills too high - shuts off boiler - HELP!

AlbertNY Member Posts: 10
In February of 2007 we had a new boiler installed, a Weil-Mclain "gold oil", in our house which has steam heat with cast iron radiators.  It has been running smoothly till spring 2011 but we have noticed that the water level now fills up  way beyond the target level and shuts off the boiler. We have had one technician come and do an annual tune up and he flushed the system and "tapped" the water auto feed to loosen up any dirt but today we again found the water level too high and called for emergency service - and this time the tech told us that the boiler was not installed with a "skim valve"  and he used a liquid called "Squick" to clean up any debris/oil in the boiler. It ran OK for 5-6 hours and the water level went way too high again and shut of the boiler again. It did not happen during late spring/summer and early fall but happened now - the heat has been on more as well.

Do you have any idea what could be the cause? Could it be the sensor in the auto waterfeed that gets stuck and does not turn of? Any suggestions/advice would be appreciated.


  • over-filling

    one thing you could try would be to turn off the water feeding the auto/over-fill. test the lwco, and let the boiler run as the lwco will prevent the boiler from dry-firing.

    if the water level does not rise up out of control, then the problem must be some delay in the return of water to the boiler, triggering the a/o-f, caused by:

    1.clogged returns.

    2.over-pressure forcing the water out of the boiler, and up into the returns.

    3.bad main vents, not relieving the vacuum at shutdown, pulling water up into the returns.

    let us know the results, and we can proceed further.--nbc
  • AlbertNY
    AlbertNY Member Posts: 10

    Would it help if the mechanical piece with the water level sensor is replaced. We have a piece outside the boiler with two pipes going into the boiler - one pipe is above the target water leveland another one is below it. Could it be that there is a malfunction in the sensor valve inside so that it turns on when the water is low but it gets stuck and does not turn off - so the water overflows? For your information the whole process to go from the water level to be OK to it overflowing and shutting of the boiler took 5-6 hours. Thanks!
  • Lwco

    Can you tell us the makers name of the lwco?

    I suspect it is a mcdonell-miller with float chamber, and if so has it been flushed regularly every week or so? If it is then it must be "blown down" to remove sediment, and to check its operation, in cutting off the burner.

    If you can turn off the water going into the auto/over-feed, then this will tell you if the water-level is dropping, and triggering the feeder, by virtue of not over-filling.--NBC
  • AlbertNY
    AlbertNY Member Posts: 10

    There is no clear manufacturer's name but I see a big V with 2 M's on top and numbers 2275 205195. Don't know if that helps. We bleed it once a week and I did noticed 2 weeks ago that when we bleed and the water level drop the lwco jump on and raises the waterlevel significantly above the target level - close to the top of the measuring glas. Does this help? Thanks for advice.
  • AlbertNY
    AlbertNY Member Posts: 10
    LWCO continued

    I have been told that a technician is now on-site and he took of the cap of the lwco pooked around in it with a tool and is draining as we speak. It seems that buckets of dirty water are coming out. If cleaning the LWCO does not do it then how can the return piped be cleaned? Can they remove the radiators and blow air or water through the return? If the return is clogged I would assume also that some radiators do not heat up which is not the case- the all get very hot on each side. Thanks. 
  • Clogged returns

    You won't know whether the returns are clogged, until you observe the operation of the boiler for a while with the feed water turned off. If the returns are clogged, then you will observe the water level being low at the end of firing, then the boiler will turn off, and then the water will eventually return slowly. With the feed on, the new water masks the symptom and makes diagnosis harder.

    The returns can be flushed, or replaced if clogged.--NBC
  • AlbertNY
    AlbertNY Member Posts: 10
    Clogged returns - cont

    Thanks! What is the process to flush the returns? Is there an chemical

    that can be added somewhere to reduce chance of clogging? And, 3, when is

    major built up of debris/particles, when is is on a lot or during

    summer period when it is not?

    By replacement I assume removing old return pipes and putting

    In new ones? This is a big involved and costly job. Any short cuts?
  • test for clogged returns?

    have you performed the observing test yet? you will need several days duration to know whether the returns are clogged, so why not just concentrate on that now.

    many people here have replaced their own returns, and you can do a search here for their experiences. in the meantime, just observe.--nbc
  • AlbertNY
    AlbertNY Member Posts: 10

    Can you tell me how I turn off the water supply into the lwco? Should there be a valve or do I need to turn-off the electricity into the lwco? Thanks for your advice!
  • turning auto-feed off

    why not post a picture of the front of the boiler, and we can give more accurate instructions. probably, it will be the valve into the auto-feed which will need to be turned off.

    if you can find the mfg's model number of the auto feed itself, then a manual could be found on the web-site.--nbc
  • AlbertNY
    AlbertNY Member Posts: 10
    edited December 2011
    Furnace pictures

     Furnace picture. Thanks for your input!
  • AlbertNY
    AlbertNY Member Posts: 10

    Furnace and LWCO
This discussion has been closed.