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Steam heat problem -- mystery leak?

AM7 Member Posts: 14
I have been having a curious problem with my Weil McLain gas system. The furnace, which until recently worked fine, has begun to lose water at an alarming rate--as quickly as 12 hours or so for the low-water cutoff to trip. I can't see any evidence of a leak, however, and the radiator valves appear to be functioning well. The only thing that has changed recently (besides reprogramming the thermostat) is that we had a french drain and sump pump system installed in the basement. The contractor insists he didn't hit a pipe anywhere ...

Any thoughts? Thanks!


  • crash2009
    crash2009 Member Posts: 1,484
    edited January 2012
    Underground returns

    Are any of the returns to the boiler under the ground?
  • Hap_Hazzard
    Hap_Hazzard Member Posts: 2,849
    They might have made an existing problem worse.

    It may have been leaking slowly for a while but, unless you were paying close attention to the water level you wouldn't have noticed. If you're doing your weekly blow-downs and replacing the water, you probably wouldn't notice that you're filling it more than you're taking out, but when it reaches a certain point, then you realize you've got a problem. The coincidence is that you got the sump system installed now, so the water can disappear before you can see it. To find the leak you'll need to go around and feel the pipe to see if it's wet. Leaks are most likely near joints because the threads make the pipe thinner, but they can occur anywhere, especially where pipes have been painted.

    But be careful. When a wet return starts leaking, it could be about ready to fall apart. Any movement can turn a small leak into a gusher, and repairing a small section can be difficult because there's often not enough metal left to cut new threads, and twisting on the pipes can break them elsewhere. Unless you're in a position to replace the whole return, you're almost better off patching it with rubber tape and chewing gum until spring.

    It's possible that they might have disturbed the pipes and aggravated a pre-existing problem without realizing it. It's almost inevitable when you're jackhammering a concrete floor right next to some aging, rusting steel pipes, but I wouldn't hold them responsible. If they'd been more circumspect they might have just refused to do the work until the pipes were replaced
    Just another DIYer | King of Prussia, PA
    1983(?) Peerless G-561-W-S | 3" drop header, CG400-1090, VXT-24
  • AM7
    AM7 Member Posts: 14

    Thanks for the replies. There's a floor-level return, but nothing underground. All the pipes outside the walls are dry, and I see no pooling water anywhere around the device. 
  • Dave in QCA
    Dave in QCA Member Posts: 1,785
    White smoke?

    When the boiler is operating, do you see an unusual amount of vapor coming out of your chimney?  If so, you might have a leak in your boiler above the water line. 
    Dave in Quad Cities, America
    Weil-McLain 680 with Riello 2-stage burner, December 2012. Firing rate=375MBH Low, 690MBH Hi.
    System = Early Dunham 2-pipe Vacuo-Vapor (inlet and outlet both at bottom of radiators) Traps are Dunham #2 rebuilt w. Barnes-Jones Cage Units, Dunham-Bush 1E, Mepco 1E, and Armstrong TS-2. All valves haveTunstall orifices sized at 8 oz.
    Current connected load EDR= 1,259 sq ft, Original system EDR = 2,100 sq ft Vaporstat, 13 oz cutout, 4 oz cutin - Temp. control Tekmar 279.
  • AM7
    AM7 Member Posts: 14

    That's a good question. I hadn't noticed, but I'll look more closely. 
  • lchmb
    lchmb Member Posts: 2,997
    you could

    flood the boiler to see if it's leaking. If your not sure how, I would suggest getting someone in to take a look as that's a lot of fresh water to be adding...
  • crash2009
    crash2009 Member Posts: 1,484
    Happy Hunting!

    A while back, one of the pro's here wrote a thread detailing his adventures while chasing down a leak that had been undiscovered for 5 years.  Leaks can be very difficult to find, even for a seasoned pro.  In the end he found and repaired it.  Maybe yours will show itself sooner rather than later.  Listed in the thread is every possibility everyone could come up with.    http://www.heatinghelp.com/forum-thread/138490/System-Losing-Water  Hopefully you find it before you have to use the last resort.
  • BobC
    BobC Member Posts: 5,473
    White smoke

    When checking the chimney for white smoke it's best to check on a really cold day so the vapor is very obvious.

    good luck,

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • Flooding the boiler

    We have a bit of a warm spell here and if your area is similarly blessed, this would be the time to perform the flood test, as the boiler will be off for several hours. As said, turn off, and overfill the boiler to the header (feel the cold temperature of the fresh water in the supply pipes). Let stand and check for water leaking into the firebox.

    If this test proves the worst fears, you may be able to replace all the sections of the boiler, rather than the whole thing( assuming the sizing of the boiler is correct for your radiation).--nbc
  • Long Beach Ed
    Long Beach Ed Member Posts: 1,188
    edited February 2012
    Steam Leaks

    If it's not a wet return and not a rotted boiler, it's a steam leak.  Look for a vent that doesn't close or a leaking radiator union or valve packing in that order.

    With dry steam, a leak is hard to find.  Remove each vent, turn it upside down and blow through it.  If you can, it's not seating.  Then wash the black ring off your lips.

    Raise the boiler pressure and run it at five pounds and look at every radiator union, especially the ones over basements where a drip of water would not stain plaster.  Tighten or dope any  valve packing nuts that leak.  Also check the sight glass washers. A leaking one on top will cause quite a bit of steam loss.

    If you still can't find the leak, replace the vents with 1/8" threaded plugs (usually 3/4" on the main vents) and pressurize the system to 15 pounds with an air compressor tapped into the boiler.  Then go around and listen.  You'll find it right away.

    That's how we do it.  Takes an hour once you have the right fittings.
  • AM7
    AM7 Member Posts: 14

    Well, it's 60 degrees here today, so not likely to see any vapor!
  • AM7
    AM7 Member Posts: 14

    Thanks for the advice!
  • AM7
    AM7 Member Posts: 14
    leak update

    Thanks to all of you who have posted. Here's a little update on the situation that might contain important information (I say might, because the thing is so frustrating):

    With "cold" weather finally here, the system has had a chance to operate more or less full-time. Yesterday when I left for work the water level in the glass gauge was healthy and the house was warm. Twelve hours later, the system took 30 seconds worth of water and the temperature was 62 degrees -- suggesting to me that the furnace had been dry for some time. I refilled it at 7 pm and promptly went around the house inspecting every radiator and pipe joint I could find for leaks. I found a few radiators with obvious drips! I was able to tighten and tape two of the three, but one was too stubborn so I simply shut it off -- we have a plumber coming on Saturday and I wanted him to see it.

    When I went to bed at 11, the water level in the glass was high and the house was warm, although the furnace was dormant at the time (the thermostat read 68 and the overnight program was set for 63, so no need to be firing).

    So, I was dismayed to discover at 6 am that the house was 59 degrees and the glass was again bone dry!

    In other words, even when not running, the system is somehow losing steam and/or water.
  • MaineGeezer
    MaineGeezer Member Posts: 1
    Leaking One-Pipe Mac Daddy Radiator

    Have a drip coming from the spacer between elements.  Is it possible to tighten the assembly rods through the radiator elements to seal the drip.  Any ideas?
  • leaking rads

    where were they leaking? most radiator leaks can be fixed, and it is important to do so. why not find out how much volume your boiler has lost by topping up to halfway, then empty out the lwco into a bucket until the boiler cuts off. that will show what volume is disappearing overnight. how old is the boiler?

    MainGeezer, can you start another thread for your leak, and post some pictures of the radiator.--nbc
  • AM7
    AM7 Member Posts: 14

    leaks all seemed to be around the nut at the joint of the pipe and the radiator itself. tightening down a bit helped.

    The funny thing about the water is that the loss seems to be highly variable. One day it might be just enough to trigger the cut-off, but on some occasions it's gallons. That doesn't make sense to me (admittedly, none of this does), because why wouldn't it always be just enough to trip the cut-off and no more?

  • Long Beach Ed
    Long Beach Ed Member Posts: 1,188
    Conditions Vary

    The conditions inside that radiator and at that union vary depending on many things.  Unlike a water supply pipe that is always under the same pressure and temperature, a steam runout is always changing.  

    How fast the radiator fills with steam, how cold the metal is, will determine the amount of condensate at that union.  And the temperature will affect how lose or tight that union seals. 
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