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Boiler Empty - Sight glass full?

st heat
st heat Member Posts: 28
I drained the boiler and then loosened the nut on bottom of sight glass and drained remainder of boiler from there. Probably had 5 times as much water as needed in the system. Filled the boiler manually using sight glass, quiet as a mouse now. Will have auto-filler checkd out.


  • st heat
    st heat Member Posts: 28
    Burnham Boiler

    The noise was so unbearable, clanging, popping, thumping - that we turned the heat off last night altogether. I had water in my steam radiator on the first floor so I assumed that there was too much water in the boiler. (Perhaps the auto-fill had failed to regulate?)
    I have drained the boiler several times and the sight glass never empties. I tapped the top of the sight glass and shoook loose some sediment, then with the boiler drained I loosened the plug at the base of the sight glass and released about a gallon of water (running clear at the end) until I saw bubbles in the sight glass. But there is still water in the sight glass and I have drained the boiler again. I cannot tell how mush water is in the tank.
    How can I troubleshoot this?
  • If the glass is full

    and you can still drain water out of the boiler, it was overfilled to the point of water rising into the system piping. Shut it down and keep draining. Have a pro look at the feeder and low-water cutoff and make the necessary repairs.

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  • Al Letellier_9
    Al Letellier_9 Member Posts: 929
    sight glass full

    I have seen this a lot lately in my inspection business. Shut off the bottom valve to the sight glass and open the drain. When it is empty, close the drain and open the valve. If the glass doesn't fill back up, either the boiler level is lower than the glass.....or the nipple coming out of the boiler is plugged and the glasss can't read the level in the boiler. I have seen 3 cracked or burnt up steamer in the past 4 months with this problem of plugged nipples into the sight glass. This is a maintenance issue that gets overlooked by many service techs. Maybe not your problem but worth looking into.

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  • Boilerpro_5
    Boilerpro_5 Member Posts: 407
    I suspect this problem is related to the increased use of Elec.

    because the gage glass piping is not blown down with the LWCO. I recently had a state inspector requuire a real blow down valve on the gage glass....a very, very good idea!


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