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Just bought house - leaking wet return?

rheckber Member Posts: 2
I just closed on my first house. It's got an ca 1992 oil-fired steam boiler Weil-McLain AB468. There were some issues with the furnace so the seller had it examined and found a water leak at the coil plate fitting and a malfunctioning auto waterfeed. The seller had those repaired and the system inspected and the heating tech said all seemed to be in good condition except he could not vouch for the wet return as it was under the cement floor. The return comes down the back wall of the cellar and goes under the slab for about 10 feet back to the furnace. I can see where they dug up a section of the floor at one point, my guess to replace a bad section.

Since moving in, I've heard the autofeed kick on about every half hour. Since the boiler was just inspected my guess is I have a leak in the wet return under the floor. How can I verify that it is leaking there?
I read someone said an infrared camera would help. Any other ways that do not involve me getting a camera?

Also, assuming it is leaking there, I have a friend whose Dad is in the concrete business and has access to a concrete saw. Assuming I cut out the floor and expose the bad section, whats the best material to replace it with? I read black iron piping but do I need to insulate it or seal it in anyway? Some things I read said back iron will rust pretty quickly underground and I do not want to have to do this again if possible?
I also heard black steel was the material to use. Is this available for the DIY? Does HD/Lowes carry it and can they thread it?

Any other help/hints anyone can provide?


  • Jamie Hall
    Jamie Hall Member Posts: 21,561
    Your autofeeder kicking on every half hour is not good. At all. And the odds would be on that wet return. One absurdly quick way to find out is to turn off the boiler and add water to about an inch below the top of the sight glass on the front and mark it. Also turn off the autofeeder, if it is separate. Then see if the water level drops. With the boiler not running, any drop is a leak -- which could either be in the boiler or the wet return, but with the boiler having been checked more likely the wet return.

    Wet returns are easy to fix, relatively speaking, since so long as the pipe stays below the boiler water line by a few inches you can run them anywhere you want. If you can run the new return above the basement floor, rather than burying it, that is much better on a number of counts. Since it is a wet return, it is relatively cool and it can be run in threaded black iron or in copper, as you please. Depends on what you or your plumber like to work with.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    EBEBRATT-Ed Member Posts: 13,844
    I would also shut the boiler off and overfill the boiler with water to make sure the boiler is not leaking.
  • rheckber
    rheckber Member Posts: 2
    edited December 2019
    Borrowed a thermal camera attachment for my iPhone from a friend. You can easily see the leak. Measured and figured out what I needed for piping and went to Lowes and had them cut and thread them. Put them on top of the cellar floor for now and later on, when I don't need heat and can open the cellar up and run a 2-cycle concrete saw I'll add 6-inch nipples to each down pipe and bury the pipe back under the floor. Whole repair was about $250 in pipe and fittings. You can see the previous repair under the pipe where they replaced a few feet of the underground pipe. If I were digging up part of the system for a leak I would have done the whole thing.

  • clammy
    clammy Member Posts: 2,984
    Nice job only comment is you should have put tees w boiler drains to have the ability to flush mud and crap out either yearly or bi yearly if your piping is not insulated then I would suggest yearly and get your piping insulated , better yet would have been to add ball valves on the drops makes it easier to power flush . I would disable the the automatic feed and run the system for a week or so so you have a idea of water use . I not a fan of auto feeds they mask issues and by the time things are a issue it possible to late because all that fresh make up water has rotted out the return . Just finishing up a similar job just hoping the boiler is not shot and the issues was only apparent when they started get pin holes in the mains caused by no main venting and clogged returns that over time flooded the mains and drained slowly auto feed to the rescue feeding water ,no hydrolevel svt but a istec water meter reading 775 gallons on a 7 year old boiler .its great you took it upon yourself and got it done also smart to put them above ground ,you could have also dug it up and put in a drainage trough w a cover a little expensive but makes checking for leaks and repair quite easy no breaking up cement. On another note you may have been able to run the as dry returns back to the boiler if there’s was enough height Peace and good luck clammy
    R.A. Calmbacher L.L.C. HVAC
    NJ Master HVAC Lic.
    Mahwah, NJ
    Specializing in steam and hydronic heating
  • KC_Jones
    KC_Jones Member Posts: 5,431
    You don’t have to bury the new ones. You could if you wanted, find a new routing around the perimeter of the basement to keep them out of the way and above the floor. For me this would eliminate the worry and expense of having them under the floor.

    Also, I’m an advocate for copper wet returns as they stay much cleaner.

    Just a couple things to ponder this winter.

    Good job addressing the problem in a timely fashion!
    2014 Weil Mclain EG-40
    EcoSteam ES-20 Advanced Boiler Control
    Boiler pictures updated 2/21/15