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Finding the leak in steam system



  • artco
    artco Member Posts: 4
    Have you ever had the boiler and lines flushed and treated, They may be full of sludge.
  • artco
    artco Member Posts: 4
    When the boiler is off for a long time does the water come back from the system and fill the sight glass? Was this a replacement boiler, I know some of the old boilers were so large they had a lot of water because of the size and were able to maintain level when steaming.
  • artco
    artco Member Posts: 4
    Does the boiler shut off on the low water cutoff safety?
    JUGHNE Member Posts: 10,782
    Back to your picture with the wall AC behind the pipe.
    You say the boiler is to the right of that horizontal steam main.
    It has a lot more slope there than shown at the boiler?

    But if your steam is traveling from right to left in that picture then it looks like a counterflow system for that side of the boiler.
    If you follow that pipe back to the boiler is there a tee with a capped nipple coming out the bottom of it?

    If so I wonder if that was the drip for the condensate returning against the steam flow.
    You said when the boiler shut down you could hear cater returning into the boiler thru the steam main.
    Could that be the drainback on that main.
    It would always be happening while steaming but the burner sound may have covered up the sound of water falling back into the boiler.
    This would give you pretty wet steam leaving the boiler and a lot of water leaving with it....dropping the level in the boiler.

    If that is a counterflow main......steam flows one way and the condensate comes back opposing that steam flow, then you need a drip to catch the condensate before it goes back into the boiler or is just flung out with the steam.
    That looks a little small to be the drip for that main. But it looks original and I can't think of why a dead man would have installed a Tee pointing down from a main. If truly counterflow and I am looking at the correct corresponding pipe/tee then it should be connected into the wet return at the base of the boiler. IMO

    This would return some water to the boiler right away without waiting for the wet or dry return from the far end of the system.
  • tfahlberg
    tfahlberg Member Posts: 19
    Thanks Skepticelt.

    By process of elimination, it has to be a leak in the left return.

    The weather finally warmed up enough to do the leak test with the clear tube. I over-filled the system about 2 feet above the boiler and took measurements for several hours and again this morning. The level in the tube dropped 28" in a few hours, and another 1/2" overnight. It seems to be stopping about 31" above the foundation, which is 4" above the top of the HL. In the photo the level started at the top of the filler plumbing and stopped at the blue tape:

    It is completely dry under the boiler.

    I can see the right return to where it goes vertical, and there is no sign of water under that elbow, so it can't be there. Therefore it must be the left return.

    The left return is mostly hidden behind drywall and insulation, but there is a gap between the studs and the foundation, which is where the water must be draining.

    I ordered a moisture detector from Amazon, but now I'm thinking more about mikeg2015's suggestion about the infrared detector. It's a reach because the return is behind the insulation.

    I know the height of the leak so that will help a little. And some sheets of drywall aren't finished, so I'll start with those. If I can't find it myself, maybe a professional leak person can find it before I demo the whole basement wall.
  • Can you fill the returns as full of water as possible? That leak should produce a stream strong enough to show up on the drywall.
    A hose attached to the boiler drain should be able to do that.—NBC
  • tfahlberg
    tfahlberg Member Posts: 19
    Wow. OK. I can fill it all the way to the big mouth I suppose. Seems like that much water has to show up somewhere!
  • Steve_210
    Steve_210 Member Posts: 628
    I don’t know if somebody has mentioned this but you can find small leaks at radiator valve gland nuts By using a small mirror
    When the system is running
  • tfahlberg
    tfahlberg Member Posts: 19
    edited February 2018
    I finally found the problem!! THIS FORUM WAS BOSS AND I COULDN'T HAVE DONE IT WITHOUT YOUR HELP! Special thanks to @nicholas bonham-carter , @JUGHNE and @mikeg2015!

    The problem was a cracked T behind a closet wall. I rented an IR camera, pressurized the system and found the problem in about 10 minutes. Check out the IR image:

    These images were impressive to me, because it was through 1/2" drywall and R-19 insulation.

    Equipment: I didn't want to spend the money buying an IR camera, but home depot had a good one for $55 for three hours which worked out great. I also bought a small two-prong moisture detector from Amazon for $25, and poked the wall all over; it beeped like mad in this area. The prongs did not damage the drywall, so I highly recommend this gadget. I also bought a cheap stethoscope but that did not help, as the fitting was dripping fast but not spraying.

    There was absolutely no bubbling in the drywall, no visible evidence whatsover. All the water was leaking into the cavity behind the studs.

    Here's a photo of the bad boy:

    This is part of the wet return, so when the outside temp dropped to -8F the water froze solid and the tee split. After the plumber fixes it we'll need to retest for more leaks.

    You guys are the best!!!!!

  • Thanks so much for the update. Many times people will find that our advice was successful, and not let us know, or unsuccessful, and then they give up.
    Find out how that pipe could have got so cold, and close that air leak too.—NBC
    JUGHNE Member Posts: 10,782
    Good for you! Thanks for the feedback.....we always wonder the outcome of problems.