Click here to Find a Contractor in your area.
Welcome! Here are the website rules, as well as some tips for using this forum.

If you've found help here, check back in to let us know how everything worked out.
It's a great way to thank those who helped you.
Need to contact us? Visit

steam boiler losing water - no apparent leaks

alano9999alano9999 Member Posts: 2
I am new to this site but have seen a few older posts on this topic and wanted to glean a little more insight into this problem.
I have a Weil Mclean boiler and every few days, I was putting in about 2 gallons of water.. I eventually put in a VXT automatic feed device to automatically feed the boiler on Low Water Cutoff because when I came home in the winter after a week away the house was cold because the LWCO was on thus shutting the boiler off.
I know that adding water to a boiler is bad but I felt I had no choice. I know that the VXT device is only a band-aid and does not get to the crux of the problem.
So this is what I did.
1) Checked all the returns - all are above ground and no apparent leaks
2) Shut off the boiler and overfilled it so no water line in sight glass. No apparent leaks
3) Checked the chimney exhaust from outside the house while the boiler was on and did not notice any
4) Checked under the radiators - no signs of water
5) Checked the spot where the water returns from the radiator after making steam and no signs of rust or
evaporation leaking .
I have lived in the house for around 20 years and do not have any signs of water leaks on bedroom ceilings or other spaces.
In my poking around, I did notice that the house has 2 mains and both of them are tapped with a 1/8 nipple to accept GORTON D valves which are radiator valves!! WOW. However somehow since we are getting heat I do not think that this has to be resolved immediately?
I would think that this would slow the heat to the radiators of which some also have Gorton D air valves but in the end, we still do have heat...
If I change to putting in a 1/8 to 3/8 coupler and then putting in a 3/8 female elbow and then putting in a Gorton #1
3/8 air eliminator valve, would this help to resolve this water loss problem?
I'm wondering if perhaps steam is too slow to circulate the system and it is somehow boiling some water away causing the water loss?
Any suggestions on this issue would be greatly appreciated..



  • IronmanIronman Member Posts: 5,513
    If steam is boiling the water, where do you think the water would go? Assuming no system leaks, it would still have to be in the system.

    Do you have any buried wet returns? If so, that's probably where your leaks are.
    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
  • Hap_HazzardHap_Hazzard Member Posts: 2,210
    Gorton #1 and Gorton D have the same venting capacity. Give us the lengths and diameters of your mains and we can calculate how much venting you need.

    To check your boiler for leaks, you need to fill it up to the top of the sections. The best way to tell if you've got it full enough is to feel the risers. They will feel cold when the water level reaches them. You can also remove the flue and vent hood and look for signs of corrosion. You won't see the steam coming out of the chimney unless it's cold enough outside to make it condense.
    Just another DIYer | King of Prussia, PA

    1983(?) Peerless G-561-W-S | 3" drop header, CG400-1090, VXT-24
  • FredFred Member Posts: 8,370
    Is this a one pipe or two pipe system? Does each radiator have vents on them? Do those vents close like they should? Does the house or any specific room seem unusually humid?
  • Big Ed_4Big Ed_4 Member Posts: 1,247
    Crank up the thermostat all the way up . Listen for any leaky vents ...

    I have enough experience to know , that I dont know it all
  • EBEBRATT-EdEBEBRATT-Ed Member Posts: 6,712
    You have lived with this boiler for 20 years. Did you always have to add this much water or has there been a recent change?

    That seems like a lot of water it's leaking out as steam or water somewhere
  • BobCBobC Member Posts: 5,081
    It's possible there is a tiny crack in a radiator that is weeping steam at such a slow rate it is not apparent. Look for any discoloring between sections that might indicate the source.

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • ethicalpaulethicalpaul Member Posts: 1,510
    > You won't see the steam coming out of the chimney unless it's cold enough outside to make it condense.

    I hope it's cold enough outside to make steam condense or else this global warming thing is really out of control!
    1 pipe Utica 112 in Cedar Grove, NJ, 1913 coal > oil > NG
  • bmmabmma Member Posts: 19
    When your boiler is producing steam, have you checked the main vents and radiator vents to see if they are letting steam escape? I was losing water from my system and noticed it was escaping the main vent. The basement never felt damp or humid, although I have a dehumidifier there that could have masked it. I wouldn't have noticed the steam loss from the main vent if I hadn't noticed the water level in boiler going down. I was surprised how much water you can lose from a leaky vent.
    Replacing the main vent solved the problem.

  • dopey27177dopey27177 Member Posts: 219
    without apparent water leaks in the system the next place to look is at the packing nuts on the radiator valves and the radiator vents.

    Try opening and closing the radiator valves. If the valve handle seems loose or opens and closes to easily the valve needs to be repacked.

    As recommended run the thermostat to maximum and check to see if some steam vapors exit the vent. if steam exits the vent you found a leaker. since your home heats well and you do not have problems such as banging or poor heating when you replace the vent valves replace with the same ones.


    With regards to vent valves if your home has a decent heat balance between rooms never try to rebalance the house. Often when some one goes down the path to try to fix something ythat a'int broke they waste time and money to get blood out of a stone.

  • alano9999alano9999 Member Posts: 2
    Thank you for all your timely replies. Sorry, I have not been so timely since I have been away and now back and dealing with this crazy problem.
    To reply to the posts in order.. For Ironman:
    1) All returns are above ground and I have seen no sign of leaks in the return piping.
    For Hap_Hazard:
    2a) As far as venting goes, I have 2 mains from the boiler:
    Main #1 is about 39 feet long
    Main #2 is about 44 feet long.
    From the boiler up to the header and then the mains -
    the pipe measures 9.5 inches in circumference which if my early math skills hold up should be 3 inch in diameter pipe.
    However, for the last foot, on each main, there is a reducing coupling to a pipe that is about 7 inches in circumference which I believe is then 2 inch pipe which has an elbow for the returns.
    On each elbow is a tapped 1/8 for a pipe nipple and then a Gorton D is then attached.
    (I had read somewhere that main air vents should be put on before the return elbow else the velocity of steam can damage the vent vales..)
    2b) I had tried to flood the boiler and there were no apparent leaks. I also believe that on a cold day, I went outside and did not see any smoke coming from my chimney. However, I want to try this again but it has not been cold enough since . We seem to be having an early spring.
    For Fred:
    3a) This is a one pipe system.
    3b) All radiators have air valves and they all seem to be working.
    (I actually had a heating guy wanting me to try changing 3 radiator vents but after changing - still the same symptom)
    3c) I have a small bathroom that with the door closed gets warm but no - have not experienced any rooms with unusual humidity.
    For Big Ed_4:
    4) All radiators get hot - before they are fully warm however, I notice a slight hissing noise which does not seem out of the ordinary to me?
    For EBEbratt-Ed :smile:
    While I have lived in house 20 years, I had the boiler replaced about 10 years ago.
    I am trying to remember the details but it seems that the water situation has gotton worse. I called the heating guys but they are stumped too.
    For BobC:
    I did not notice any water marks on radiators indicating a leak.
    (I would love to find one - however - I need to investigate this more thoroughly)
    For EthicalPual:
    I agree - I am in New Jersey and doubtful if we will have any more cold days. Perhaps I would not need to run my boiler anymore which would certainly solve this problem.
    For Bmma:
    As mentioned, I would love to see water. Did not see any coming out of main vents or any other sign of water under radiators or stains in ceilings..
    For Dopy27177/Jake
    I checked the radiators and did not notice any loose valve handles or air valve problems. I will double check however.

    Again thank you all for your responses:
    I am trying to sum up ,
    I agree that the water has to be escaping somewhere however I wish I could find out where. In this case, I would love to see water in the house somewhere.
    I will re-investigate the radiators but am pessimistic about finding the culprit without some rusty water marks on radiators.
    Perhaps water is evaporating at the radiator handles or pipe unions or between floors, but I have not found anything obvious.
    To be continued....

  • New England SteamWorksNew England SteamWorks Member Posts: 1,305
    So your boiler is using more and more water. Time to test for a corroded boiler block (unless you have underground/buried condensate return lines)

    98% of steam boilers die when the boiler block corrodes through. On steam boilers this always happens above the waterline. Therefore water does not leak out onto the floor (because a steam boiler is only half filled with water). Instead, steam exits the hole and goes up the chimney.

    In order to test we need to completely fill the boiler with water. If there is a hole, water will leak out and onto the floor.

    The challenge is knowing when sufficient water has been added. Once the visible portion of the gauge glass has been surpassed we have no obvious way to keep track of it. If we go too far we'll have water coming out the radiator vents and damaging the floors in the house.

    But before we get started we first need to be certain that after the test we can drain the excess water back out and bring the water level down to 1/2 - 3/4 up the gauge glass where it belongs. Sometimes boiler drains get clogged up. So find a bucket and place it under the boiler drain and open up the drain. If water flows freely into the bucket, -we’re good. If not, you are going to need us to come out. Assuming we're good, keep the bucket there. If there is a big hole you’ll want to start draining quickly to reduce the amount of water on the floor needing clean up.
    1. Turn off the switch on the boiler.
    2. Identify your main steam vent(s) located on the condensate return(s) pipe(s), generally in close proximity to the boiler.
    3. Slowly add water to the boiler. Nothing will happen until we’ve gotten above the level of the gauge glass so you can relax somewhat up to that point.
    4. After which, keep a sharp eye on the floor and the main vents for signs of water. One or the other is going to get wet.
    5. If it is the floor, immediately stop filling, and proceed to step 7.
    6. If it is the vent, stop filling and wait 30 minutes. After 30 minutes observe the floor around the boiler for water. If none, -you’re good! Problem lies elsewhere.
    7. Drain the excess water out of the boiler. Using the bucket (or hose if you have a sump) drain water out of the boiler until it is back to normal, approximately 1/2-3/4 up the gauge glass.
    8. Turn the boiler switch back on. If there was a leak, wait an hour before turning back on to let things dry out a bit.
    If you have a hole it’s okay to run the boiler on an emergency basis. But we need to get to work on a replacement asap. Flue gases + steam are very hard on chimney masonry and liners, and it’s expensive to heat the neighborhood. But you’ll have heat until you can install a replacement.

    New England SteamWorks
    Service, Installation, & Restoration of Steam Heating Systems
  • Hap_HazzardHap_Hazzard Member Posts: 2,210
    Also make sure your pressure limit is set as low as possible. The higher the pressure the more you'll lose from the leak.
    Just another DIYer | King of Prussia, PA

    1983(?) Peerless G-561-W-S | 3" drop header, CG400-1090, VXT-24
  • PrecaudPrecaud Member Posts: 211

    Also make sure your pressure limit is set as low as possible. The higher the pressure the more you'll lose from the leak.

    Counterintuitive, that. How does a boiler with a leak above the water line build pressure?
    1950's Bryant boiler in a 1-pipe steam system at 7,000 ft in northern NM, where basements are rare.
    New England SteamWorks
  • Hap_HazzardHap_Hazzard Member Posts: 2,210
    A small crack can still allow some pressure to build.
    Just another DIYer | King of Prussia, PA

    1983(?) Peerless G-561-W-S | 3" drop header, CG400-1090, VXT-24
  • KC_JonesKC_Jones Member Posts: 4,383
    Precaud said:

    Also make sure your pressure limit is set as low as possible. The higher the pressure the more you'll lose from the leak.

    Counterintuitive, that. How does a boiler with a leak above the water line build pressure?
    Unless the leak is large enough to allow all the steam out at the exact same rate of production, it will build pressure.

    My boiler has (2)-3" outlets. In order for it to not build pressure, the leak would have to be fairly large.
    2014 Weil Mclain EG-40
    EcoSteam ES-20 Advanced Boiler Control
    Boiler pictures updated 2/21/15
  • Jamie HallJamie Hall Member Posts: 12,327
    Precaud said:

    Also make sure your pressure limit is set as low as possible. The higher the pressure the more you'll lose from the leak.

    Counterintuitive, that. How does a boiler with a leak above the water line build pressure?
    It doesn't. Or not much. But you don't need much to move the steam to the rest of the system -- so the system will, most likely, heat just fine (illustrating, if you need an illustration, that you don't need pressure to heat a building with steam!). But -- some steam will go out the leak. Along with a good deal of your money.
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
Sign In or Register to comment.


It looks like you're new here. If you want to get involved, click one of these buttons!