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Moisture droplets inside upper part of glass tube

Ritzy Member Posts: 34
I just took a bucket of water off my Weil McClain steam boiler, 45,  (after lowering the thermostat) and noticed moisture droplets inside the upper part of the glass tube.  I never noticed these moisture droplets before. 

Since my boiler has been banging inordinately, I was wondering:  Does this excess moisture in the upper part of the glass tube of my steam boiler signify any obvious problems with the boiler?  Any problems, perhaps, related to its banging loudly few a few minutes at start up?  Thank you.


  • BobC
    BobC Member Posts: 5,407
    Some questions

    Droplets of water in the upper part of the sight glass is usually an indication of wet steam.

    How old is the boiler and do you know when it was skimmed last?

    What pressure is the boiler running at?

    How dirty was the water you drained off?

    Does the water level in the sight glass bounce up and down when the boiler is making steam?

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • Ritzy
    Ritzy Member Posts: 34
    To BobC...re: Water Droplets

    The boiler (Weil McClain EG45) was installed in August, 2000.  The water was almost clean when I took off a bucket...just a very, very light orange tinge to the water.  The water level does move up and down in the glass tube during operation...very gently.  It doesn't make high bounces in the tube.  I have the boiler checked by the gas company (under contract) every summer....I am not sure if any of those servicemen every skimmed it.  I am ignorant of the pressure at which the boiler is running...how could I determine that? Thank you!
  • BobC
    BobC Member Posts: 5,407
    Gauge should be near the sight glass

    There should be a pressure gauge and a pressuretrol on the boiler in the same general area as the sight glass. That pressure gauge should read zero when cold (or just warm) and not more than 2PSI when making steam. Original steam pressure gauges really are not very good at the low end so the reading might not be accurate. The pressuretrol should be set so the boiler runs between 0.5 and 1.5 or 2PSI - The tab on the front should be set way down around 0.5 and the white wheel inside the pressuretrol should be set to 1.

    If the water appears clean and there is not a lot of bouncing up and down on the sight glass that leads to more questions.

    Has this banging started just recently (or has it always made this noise); if so was anything done to the system (changed any piping or radiators) before the banging started?

    Your system looks like a single pipe steam system, there should be an air vent near the end of the steam main. Do you know if your main air vent is working?

    Take some pictures of the pressuretrol, the pressure gauge, and that main vent and post them with your reply. Also assuming it is a single pipe system, are the air valves on the radiators working?

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • Ritzy
    Ritzy Member Posts: 34
    For Bob: Pictures of System

    I am attaching pictures of my system, along with pictures of where the basement-ceiling-pipe vents are.   I am not sure if these are the vents you mention.

    The banging started about 5 years ago...and, has progressively gotten louder.  The banging noise comes from the boiler itself...it is not water-hammer in the radiators or upstairs wall-pipes.  No changes were made to the system since it was installed in August, 2000. 

    Vertical, basement pipe vents haven't been touched in 30 years.

    Thank you so much!
  • Steamhead
    Steamhead Member Posts: 16,230
    I agree, it needs to be flushed

    there's likely an accumulation of sludge in that boiler. This is most critical in atmospheric gas boilers like yours, since the burners are completely below the cast-iron sections, and if there is sludge on the bottom of the sections it blocks a lot of heat transfer.

    And those cute little Dole main vents are probably way too small. Measure the length and diameter of your steam mains and we can tell you what you need.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • crash2009
    crash2009 Member Posts: 1,484
    Moisture droplets

     in the upper part of the sight glass would suggest to me that one or both of the sight glass tappings are plugged.  I would have them dis-assembled and cleaned.  Also, the water in the sight glass looks too clean, again this suggests to me, that something is plugged and not circulating.

    In your photo of the sight glass, there is a square plug, just to the right of the sight glass.  On my Weil Mclean EG-55, this is where my skimmer is installed. 

    Steamhead works on these things everyday, if he says the boiler needs to be flushed, I would start shopping for someone to thoroughly clean it.

This discussion has been closed.