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LGB-8 boiler needs 4 gallons make-up water per day!

bkc Member Posts: 37

I'm maintaining an LGB-8 boiler (22hp, 543 MBH net) 2-pipe system with 3 condensate pumps and a boiler feed pump in a church. There are NO buried returns and no visible leaks from any piping.

We installed a water meter last fall on the make-up water feeding the boiler feed tank. I've just gotten around to tallying water use vs drained water (one 5 gal bucket per week for LWCO cleanout)

Anyway, in Nov loss was about 1 gal/day, Dec 1.8 gal/day, Jan 3.7 gal/day and Feb 4.2 Gal/day

In the first week of Jan I discovered a failed actuator whose related 2" valve stem leaks a little. We're going to replace both the actuator and valve after heating season. In the meantime I have to manually open the related service valve each Sunday for an hour. Otherwise, that service valve is off all week. I've discovered that the service valve stem leaks a little too, and this might account for some of the increase in water loss in Jan/Feb

We have 2 main line air vents that might not be closing properly, sometimes I hear them venting for longer than I think they should.

And there's 4 F/T traps feeding a condensate tank that I hear bubbling sounds from, but not a lot of steam escaping from the relief vent. The valve I'm keeping closed most of the time ultimately ends in one of these F/T traps, so I'd expect steam loss to go down when the valve is kept closed.

Anyway, is it possible that a couple of valve stem leaks can lose 4 gallons a day?

here's a video of the two leaking stems:


There is one single-pipe radiator attached to the system (on the line I've been closing), it's steam trap does close after it warms up.

Where else can I look for leaks?



  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,840
    edited February 2022
    See if steam is exiting the chimney. indicating a leaking boiler section. No water on the floor because all the water is out the combustion vent. Talk about condensation in flue gas vent. That can loose a few gallons.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • Jamie Hall
    Jamie Hall Member Posts: 23,310
    That is a big enough leak that you might actually see it -- or feel the increased humidity somewhere. If it were a leak. But that much water? Check for steam (not just condensation, steam) coming out the chimney. I'm thinking you have a boiler leak above the water line.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • ethicalpaul
    ethicalpaul Member Posts: 5,702
    Steam is invisible but otherwise yeah :wink:
    NJ Steam Homeowner. See my sight glass boiler videos: https://bit.ly/3sZW1el
  • bkc
    bkc Member Posts: 37
    Thanks, I will try to get off work and look at the chimney exit. This boiler is only 3 years old.
  • KC_Jones
    KC_Jones Member Posts: 5,737
    Just something to think about. I think 1 gallon per day is excessive and should have initiated the search for a leak. I could see a gallon per week, but not per day, even on a big system like that.
    2014 Weil Mclain EG-40
    EcoSteam ES-20 Advanced Boiler Control
    Boiler pictures updated 2/21/15
  • dopey27177
    dopey27177 Member Posts: 887
    Try this if water vapors is not visible from the chimney.

    Flood the boiler, try to get the water level up to the start of the steam main. This will put a static head pressure on the boiler. If the boiler has a leak above the water line water should spill out on the floor.