Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Missing water

Jim_64 Member Posts: 253
Mark, turn the service valve or shut off at the radiators if you can move them easily you may be leaking from the packings ,if thats the case you can almost always tighten or repack em.


  • Boston_2
    Boston_2 Member Posts: 107
    So I have finally worked out 90%

    of the issues with my new boiler, except one nagging problem; Where on earth is my water going. I marked off the site glass on my new boiler in increments of an inch to see how much water I am loosing. Ever 2 weeks, I loose about ¼ inch of water in the site glass (not sure what that equates to). I have checked all the radiators/valves and connection and amazingly everything is dry. I have checked the chimney to see if I see any steam… and nothing.
    Is it possible that the water level is building up in the wet returns? Or condensation I the radiators? It has to be going somewhere.
  • lost water

    the radiators and other areas will only hold so much and then no more.
    are you checking your water level when cold? if you check it while hot you could be seeing the lag volume of waiting for condensate to return.
    a disscussion of this is here:


    with add'l here


    you can always measure this volume by filling the boiler to the normal level, and draining the lwco into a bucket until the lower level is reached; and then measuring the volume in the bucket.--nbc
  • Big Ed_4
    Big Ed_4 Member Posts: 2,712
    Do you have......

    .... Any radiatiors shut off from using the shut off. If so open the valve and plug the vent tap.

    Run the boiler on pressure and go around the house and lisen for steam leaks.

    Check the wet returns for leaks. Underground sections I always suspect.....
    I have enough experience to know , that I dont know it all
  • Boston_2
    Boston_2 Member Posts: 107

    It funny, after the boiler stops running, the water level is slowly goes up in the site glass then drops back down when it’s cold. I just had the wet returns replaced so I wouldn’t think that is the problem. In the mornings, I do hear a little gurgling from some of the radiator valves, but nothing significant. I checked to make sure that all the radiators valves were open. It is possible there is a leak inside the wall? I checked to see if there was any moisture below the new boiler and it’s dry as a bone.
  • David Nadle
    David Nadle Member Posts: 624
    Doesn't sound like a lot of loss to me.

    I think you can expect to lose a little water over time. I wonder what the waterline surface area is. I'd hazard a guess you're losing less than a tablespoon a day.
  • Imperfect Vents

    The air vents on any system are bound to let out a little steam every time they vent, right? They can't respond instantly and there has to be some water vapor even in the air that vents. A few seconds before my Hoffman radiator vents close, I can hear a minor change in pitch . . . it goes from a faint "SSS" sound to more of a "SHHH" sound . . . if that makes sense. That's got to be water in some form finally hitting the vent, maybe even steam condensing as it hits the cooler metal of the vent. The bimetal Gorton and Maid-o-Mist vents don't snap shut like the alcohol filled Hoffmans either. They definitely vent a little steam as they slowly close. Also, my taller, old column style radiators seem to vent the air in one or two cycles, and then stay closed. My shorter tube-style radiators vent a lot more often.
    I'd bet that the extra height and space of the column radiators, combined with the less maze-like internal passages work better to keep the steam and air separated.

    In the coldest part of winter, my 175,000 BTU boiler loses about a half inch of water per week. I considered that a pretty tight system. Am I wrong?
  • mark ransley
    mark ransley Member Posts: 155

    I loose more than that every day on a old giant Kiwanee, now thats gallons a day. How much water does yours hold, it may not be loosing much, air vents going bad, maybe a radiator valve stem leak or two, something loose, and the water is gone. Maybe run it to pressure,and increase pressure on a test and go look and listen for some leaks.
  • Boston_2
    Boston_2 Member Posts: 107

    Between both the wet returns and boiler, I think the system holds about 15 gallons. I tested it out and it looks like I lost about 1 gallon of water in 2 weeks. That seems like allot to me for a brand new system. You would think that kind of water vapor would be something you would notice, but I don’t see any wet spots. One day the pressure got up very high (10 psi – the pressuretrol was not setup properly) on the boiler and I did notice that every radiator valve started to andhiss leak. Is it possible that they are leaking and I just can’t see or hear it?
  • David Nadle
    David Nadle Member Posts: 624

    Draining a gallon moved your waterline only 1/4"? That's a lot more water than I expected.

    How long has it been since you reset the pressuretrol? Are you still losing water at the same rate?

    I believe that if a vent were leaking steam you would be able to hear it.
  • SusanC
    SusanC Member Posts: 106

    Am only a homeowner, but sounds good to me. From what I understand, an open system such as a steam system is will lose some water. I have a feeling that people who say it never should lose any water are speaking of a system in which EVERYTHING is perfect, e.g. no tiny loss of steam from any vents, etc., - good on paper or electronics but appears not usually to be the real world.

    A steam expert on this forum wrote this some time ago:

    "...Here's what we found to be a good rule of thumb: In mild weather (fall & spring), a steam boiler should not need water feeding more than once a month! In winter, a good tight steam system should not need feedwater more than once every two weeks!

    Without getting into the water level in the sight glass when full, or near empty nuances, the above two week and one month intervals are a base level of understanding a "tight system" (which is essential) vs. a "loose system" (which is the death knell for steam boilers)."

    Sorry not to reference the author, but I thought I'd let identified people speak for themselves.
  • mark_120
    mark_120 Member Posts: 6
    gaze into the mirror

    To get down to brass tacks the best way a have found to find a leak is to use a hand held mirror.
    You can wave it behind radiators pipes if you have a leak it will find it.
    The trouble with small leaks is they don't emit a audible frequency to the human ear, it has to do with dynamic expansion of steam and it ability to dissipate its enthalpy.
    Given a large leak you can see a plume and hear, a small leak just wiffs away undetected.
    Use a mirror and you might see what you have been missing.
  • Jim Franklin
    Jim Franklin Member Posts: 170

    One word evaporation .

    It's an open system.

    You can't see it
This discussion has been closed.