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Have to refill steam boiler once every two weeks

Hello everyone, I hope everyone is staying warm!
With the weather in teens these past 2 weeks here in NJ I realized that I have to add about a gallon to a gallon and a half of water to my Weil McLane EG 40 steam boiler every two weeks. Normally, during milder weather temps, I can last a month without adding any water. My radiator vents are all new and don't leak steam, no leaks in the pipes, and the pressure is low. The boiler does run a lot right now. I know some water does evaporate with each cycle, but a gallon in just two weeks.... ? Is it excessive?


  • FredFred Member Posts: 8,418
    If there are no obvious signs of a leak, anywhere, I would wait for the weather to get back in the normal range, maybe 30's, and see if the water consumption is more what you normally see. It's been really cold and boilers have run a lot. Hard to gauge unusual water consumption when we have such an extraordinary span of frigid weather.
  • Danny ScullyDanny Scully Member Posts: 1,221
    When you say you have to add water, is the LWCO shutting the boiler off or are you preemptively adding water?
  • RomanGK_26986764589RomanGK_26986764589 Member Posts: 221
    @Danny Scully I preemptively add water.
  • Mark NMark N Member Posts: 1,087
    As a matter of reference I've added a 1/2 gallon of water since October. Check your packing nuts on the valves, the union between the valve and rad, and the main vents.
  • JohnNYJohnNY Member Posts: 2,432
    1 gallon or so every two weeks for a ~125 MBH boiler is fine. It's on the high side of normal but it's fine.
    For installations, troubleshooting, and private consulting services, find John "JohnNY" Cataneo here at :
    "72°F Mechanical, LLC"
    Or email John at [email protected]
    John is the Boilers and Hydronic Heating Systems Course Instructor at NYC's Mechanics Institute, a professional Master Plumber, licensed by The Department of Buildings of The City of New York, and works extensively in NYC while consulting for clients in and out of state.
    John also oversees mechanical installations and maintenance for metro-area clients with his family's company, Gateway Plumbing and Heating along with his brother/business partner.
  • Danny ScullyDanny Scully Member Posts: 1,221
    @RomanGK_26986764589, my advise would be to stop adding water and wait until it actually goes off on low water.
  • RomanGK_26986764589RomanGK_26986764589 Member Posts: 221
    Quick update, the good news is I found a leak!
    It is a radiator runout on the first floor bathroom. The bad news is that I will need to break up that tiled floor to get to it. I'll probably do it in spring or summer when I won't need the heat just in case something goes wrong.
  • FredFred Member Posts: 8,418
    Good for you ! Goes to show, when you know your system, you know when something isn't quite right.
    New England SteamWorksRomanGK_26986764589
  • RomanGK_26986764589RomanGK_26986764589 Member Posts: 221
    @Fred Yep. I fanatically check the sight glass at least a few times a week so that's why I don't even have an auto water feeder. :D
    I eliminated a night setback until I fix the leak because it only seems to pronounce itself when the boiler hits 1.6 psi of pressure and cuts out during setbacks or during this extreme cold we had where the boiler would run a lot and hit that 1.6 psi quite often.
  • RomanGK_26986764589RomanGK_26986764589 Member Posts: 221
    Also, a curious thing I noticed, I never had to add water to the boiler more than once a season. So now when I added water a couple of times due to a leak I noticed how calm my 0-3 psi gauge has become. I though the opposite would happen, i.e. more water I add more minerals I introduce to the boiler and water should boil more violently but, for some reason, the opposite happened. The gauge needle almost doesn't shake and is very precise. The sight glass water bounce also decreased from about 0.5 of an inch to about 0.25 of an inch. The trap itself with controls on it is clean and the pressuretrol does cut out at 1.6 psi and cuts back in at 0.7 psi. when coming back from a setback. Any ideas why adding water makes the boiling more stable?
  • FredFred Member Posts: 8,418
    @RomanGK_26986764589 , I see the sight glass water level out to almost no bounce on the occasions where I add a little water but I have concluded that it is more likely that it is the result of a little cooling of the boiler water and a little less boiling action. I don't stand around long enough to watch things come back up to a full boil where I get about a half inch of bounce.
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