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Noisy Boiler, only in the middle of the night

BillC Member Posts: 1
I have an old American Standard model GPH-100 boiler which runs great , except I get loud gurgling noises from the boiler (as if the laundry washer and dryer are running) but this happens only in the middle of the night, when thermostat is set low and ambient temp drops. Otherwise the system runs great during the the day. Had three technicians visit - all are puzzled and recommended a new boiler. Some guess it's sediment or scaling causing steam bubbles to explode, but I'm not convinced. Thinking about flushing the system to rid of possible air pockets, but not sure how with this plumbing set up. Any suggestions would be appreciated.




  • Tim McElwain
    Tim McElwain Member Posts: 4,588
    Typically on that boiler it is not

    air pockets but deposits in the bottom of the heat exchanger/boiler sections that are doing what is called "Kettling" it is caused by water getting into the deposits in the bottom of the boiler sections and due to difference in temperature directly above the burners and the water it will create steam and when the hot steam hits the cooler boiler water they will gurgle or kettle. You could try having the inside of the boiler flushed but my experience with that particular boiler it will not work most of the time. Probably time for a new boiler or just put up with it.
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