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Boiler over filled

Issue---Just realized our boiler was over filled. We have an automatic low water cut off which I had removed and cleaned this past fall, along with draining and flushing the 3 year old wet return. I drained the boiler until the low water cut off light was activated, waited through the delay and watched it fill to the normal level and shut off like it should. I pride myself in keeping a close eye on my system and it's maintenance, but must admit this one has slipped by me.  Questions: 1) Can these cut offs operate sporadically? 2) What should I be looking for?  

Happy Holidays!



  • diytrainee
    diytrainee Member Posts: 1
    boiler overfill

    is there a leak in the water  feed.. ?   listen to the pipe that feeds from the water feed

    into the boiler.  You might hear the water running.
  • Robbie
    Robbie Member Posts: 41

    Could you have a slow condensate return? The automatic water fill should have an adjustment for condensate return time IIRC. If this has changed for some reason, then perhaps the low water triggered the auto fill, which did not give sufficient time for condensate return, filling it to proper level, which then got raised when the condensate came back after...

    Just a thought-

  • Jamie Hall
    Jamie Hall Member Posts: 23,433
    Did it go wonky

    right after you worked on it, or did it wait a while? 

    I'd be very suspicious of a leak somewhere, like in the valve in the autofill.  For that matter, some autofill piping arrangements have (they all should have, but...) a bypass manual fill.  Could that be leaking, or the valve joggled open a bit?  Try shutting off the water to the autofill and the bypass, if you have one, and see if the level is stable.  If it rises, at least it isn't either of those -- and you need to figure out where else water can get into the boiler.  A domestic hot water coil, perhaps?

    If it is, then turn the autofill back on and see if the level holds.

    In my experience, slow condensate return usually doesn't just happen all of a sudden, but builds up as a problem rather slowly.  Robbie's comment has merit, though -- if there is a time delay on the autofill, could that have gotten changed?
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • terry ritter
    terry ritter Member Posts: 10
    Boiler over filled

    Thanks for all the responses! The overfill has only happened the one time prior to my post, and has shown no issues since. I'm keeping a close eye on it and will look into the other suggestions. Thanks again!

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