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Weil McLain Gas Steam Boiler

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mb23
mb23 Member Posts: 8
edited 1:08AM in Gas Heating

Hello,


I have a brand new Weil McLain gas boiler with a Steam heating system. When asking for heat, the LCOW is constantly going off and water would be added to the system. Is this normal? I am not sure where I am losing water at. There is no leak unless at the radiator air vent that I hear hissing at times. What could be some potential causes for this. If the boiler is off, the water maintains its level and it does not overflow.

Comments

  • Steamhead
    Steamhead Member Posts: 18,383

    Pics?

    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 11,964
    edited 2:08AM

    Lots of reasons for this. More info required.

    The first one that comes to mind is a bunch of pin holes or a crack near or just above the water line. This will allow the boiler to appear to operate normally while letting steam (that used to be water) leave the boiler and end up inside the exhaust vent. This would look like white smoke out of the chimney when the boiler is making steam. Since there is steam leaving the system, there needs to be water added to replace the missing steam.

    The test for that is to turn off the burner and allow the boiler to cool off for 2 hours or more. Then add water so it goes above the gauge glass. See if any water starts to leak on the floor. You can fill the boiler with water but you don't want the water to get into the steam mains.  Close the valve before the water gets too high.  Just enough water to reach that leak so it spills out of any cranks onto the floor.  Allow the water to remain that high for 30 minutes or until you see water. 

    If you don't find a leak that way, then let water out the drain valve until the water line goes back to the middle of the gauge glass before turning the burner back on. 

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 11,964

    Another common leak is the wet returns. Especially if they are under ground. Wet returns are any return pipe that happens to be below the boiler water line. Old iron pipes are noted for rotting away. And if they are underground, you will never see that leak.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • STEAM DOCTOR
    STEAM DOCTOR Member Posts: 2,582

    Unlikely to be wet return issue, if problem is only happening while boiler is firing. It's a brand new boiler, so hopefully no leaks within the boiler itself. You can try to fill the boiler past the top, just to confirm. Do you have any hidden returns? Had this with a customer recently, with the boiler that I had put in a year or two earlier. Turns out there was a dry return, running through a crawl space, buried in dirt. Was leaking steam like crazy but nobody knew

  • mb23
    mb23 Member Posts: 8
    edited 3:40AM

    Thank you all for your comments. No leaks within the boiler and we rerouted the return recently back in October. Interestingly enough a week after the return was rerouted, the boiler flooded and water was coming out of the main air vent at the return line. More than 20 gallons of water were removed and since then it has not overflow, I check the water level every 3-4 days. However, it short cycles because only enough water is added to meet the minimum level ( about half of the gauge glass) and then it igniters and a couple of minutes later water level drops and it short cycles with the LWCO going off. Should I increase the water feeder from its default setting of LWCO to 1 gallon? I have the VXT-24 auto feeder. Could it be that the boiler is oversized for the system? Or maybe contamination from the new return line that was rerouted and would need to be skimmed.

  • 4GenPlumber
    4GenPlumber Member Posts: 106

    Post pics of boiler, near boiler piping, return work, radiators...as much as possible. Nobody can diagnose without info. All we could do is speculate every possible problem that could result in low water.

  • 109A_5
    109A_5 Member Posts: 3,829
    edited 3:55AM

    " I have a brand new Weil McLain gas boiler with a Steam heating system. "

    New Boiler !!! Was it ever Skimmed ?

    Has this been going on since the the install ?

    I'd say the boiler needs Skimming to get the manufacturing oil out of the system.

    The oil coating the top of the boiler's water causes eruptions sending the water out of the boiler tripping the LWCO, possibly eventually flooding the boiler due to water being added when the system as a whole (behaving normally) really does not need more water.

    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
    mb23
  • mb23
    mb23 Member Posts: 8
    https://forum.heatinghelp.com/discussion/comment/1889086#Comment_1889086

    Thank you! I think this might be the cause as well. Looking at the VXT-24 auto feeder it has only had 4 gallons since its installation ( June 2025) and has been 4 gallons since October it might not be an actual water loss- unless that is not registering it correctly which it is also new. I will have to ask the contractor who installed it to skim it.

  • 109A_5
    109A_5 Member Posts: 3,829
    edited 4:25AM

    20 gallons removed Vs. 4 recorded makes no sense. Maybe you have multiple issues.

    If it was never skimmed it probably needs it. And it may need multiple attempts since the oil was possibly blasted into the system by the eruptions and returns slowly.

    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 20,039

    @mb23 You need to post pictures. How does the sight glass look? Clean or dirty? Does the water level bounce when the boiler is steaming" Does it move more than an inch?

  • mb23
    mb23 Member Posts: 8
    https://forum.heatinghelp.com/discussion/comment/1889090#Comment_1889090

    agreed, something does not add up. Maybe from the return at that time? It was really cold and temperature was set at 73 degrees during that week not sure if that helps. It was the only time it had that much water. All other times it does not overflow.

  • mb23
    mb23 Member Posts: 8
    https://forum.heatinghelp.com/discussion/comment/1889091#Comment_1889091

    sight glass looks dirty (brown) but the water itself is clean( now). The water level bounces a lot while steaming until it finally goes to the level where the LWCO is triggered.

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