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Steam system pin hole leaks

Hi searching for an answer to a problem that has me bogged and Google or YouTube hasn’t been able to help. We installed a new boiler for a client. Which we had advised him someone had did some repairs to cast and steal piping replaced with copper and piping was piped bad. But client didn’t want us ripping his finished basement apart. So declined to have us fix and just install boiler and near piping. So boiler works great and we skimmed and add steam clean to system to help make efficient and clean out years of crap. Sure enough there’s slot of banging and water hammer. But we warned him and he did say system already have existing. So 3 days later we get called back he has a leak and we found a pin hole in bottom of return pipe in soffit. We temporarily repaired and set a date to come back and replace 10 ft section with new piping. But then he had 2 more leaks like a few feet apart so we repaired pipe, a week later another leak on a different section. So are going back to fix again, looks like pipe is newer and was repaired before. It’s steal pipe and almost looks like perfect holes drilled but of course they are not. Customer says he didn’t have this problem before new boiler but admits to the banging and again it looks like this pipe was repaired before🧐 now in boiler room there was repairs as well hand changed to copper as well but not leaking there. Does anyone have an idea or know what’s causing this I talk to several people and they say it not the steam clean additive because it’s a safe mild cleaner made for system systems. Could it be the hammer and banging causing this? It’s perfect little joke directly on bottom of return piping. With few feet of each in a line. Please help trying to help this guy and give him answers thank you in advance.,


  • Hap_Hazzard
    Hap_Hazzard Member Posts: 2,826
    Can you get any pictures of the pipe that was replaced (inside & out)?

    Is this a wet or dry return?

    Were the holes in various places around the diameter of the pipe or could they all be in the weld? I've never seen schedule 40 pipe fail that way, but if I saw relatively new pipe perforating, I'd certainly look at that.
    Just another DIYer | King of Prussia, PA
    1983(?) Peerless G-561-W-S | 3" drop header, CG400-1090, VXT-24
  • Jamie Hall
    Jamie Hall Member Posts: 21,114
    A few comments.

    First, There should, as I'm sure you are aware, be no banging or sloshing, even in a new install. If there is, that needs to be addressed. Now granted, since he has a finished basement, that may be difficult, since a lot of it will be in the pipe pitch being off.

    Second, in connection with the banging and sloshing, check the operating pressure. Anything over 1.7 psi cutout is too much.

    Third, check the water line elevation in relation to any wet returns. Although I'm sure that you matched the new water line to the previous one, that is no guarantee that the previous one was correct. The party before you could have messed up. Any wet returns and the bottoms of any drips must be below the lowest safe operating level of the boiler.

    Now on the leaks. If they are on or near the bottom of ductile iron pipe, and they are on wet returns, this is not wholly unexpected. Best to replace the entire length. If they are scattered around a wet return, and the pipe was subject to a moist, corrosive environment (some types of mortar, coal) that also is not unexpected -- again, replace the entire length. Leaks in a dry return or steam main, however, suggest very strongly that that length of pipe is not pitched correctly, as neither one should ever hold any water. That is, if they are from the inside out. If the pipe is steel, rather than ductile iron, it's not a bit surprising. Steel pipe rusts.

    The steam clean additive is not likely to be the cause. It's also not likely to be needed, and if it is in use in any significant amount it will contribute to the banging and sloshing.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    EBEBRATT-Ed Member Posts: 13,442
    I suspect excess water make up in the past. The system probably has or had a lot of leaks.

    Make up water will eat pipe and boilers so any leaks need to be addressed before he loses the new boiler
  • John732
    John732 Member Posts: 16
    Hello again . Thanks for your comment, to answer some. It’s a dry return . And the near boiler piping we did is fine no problem at boiler , yes pressure trol is set correctly I double checked that. The issues are definitely further on down the system which we told guy from the get before we started. Now one of my suspicions is there was problem from before because holes are in dry return which is in soffit in ceiling and looks fairly new , like replace within last 3-4 yrs but I don’t know exactly.the original pipe has to be 40-50 yrs old and you can see the difference in pipe we replaced. It is in steel piping and all along the bottom the pin holes. Now I know there’s not much of pitch which who ever finished basement may have messed with that.  I don’t have pics but it wasn’t all mudded up and I  couldn’t really see if inside was pitted. Outside of piped looked fine except for perfect round pin holes. As far as the steam clean yes I was told it couldn’t be that, we put in old system that were poorly maintained to get rid of muck and bring to bottom of boiler where it can be flush out. Also the stuff steam clean helps with surging, but yes we did skim . I’m just wondering if banging is causing holes. I also think the guy had a lot of filling of water due to leaks and bad vents in passed. We fixed 3 of his vents the were shut open pissing out steam . 
    EBEBRATT-Ed Member Posts: 13,442
    edited December 2021
    Too much make up water in the past. And probably bad pitch as well. Pipe above the water line should last ....forever. I would allso take a sample of the boiler water and test the PH. Banging would not cause the holes. Banging would cause leaks at elbows at the end of the pipes

    The 3 open vents probably were part of the issue
    JUGHNE Member Posts: 10,573
    The only leaks above the water line, that I have seen, were dry returns that were holding water after the system was off and should have drained dry back to the boiler.

    Lack of correct slope. IMO
  • John732
    John732 Member Posts: 16
    Thank you all  for your feed back . Just found this all too strange. I have been doing boilers for alittle while and a advocate of doing things correct and always taking advice from those with more experience than me. I’m always reading , search for more information and just needed some reassurance of what’s going on. I think we did the best we could and customer was told from beginning. We are trying to convince him to let us tare down sheet Rock & fix all issues best we can. Thank you all . Happy new year
    STEAM DOCTOR Member Posts: 1,652
    @John732. Banging was there before. So obviously not your fault. The worst boiler install won't cause returns to leak. Dry returns are leaking. There is banging. Possibly have all the monkeys dancing around the same fire (I.e. one cause for both problems). There is likely an issue with pitch in the dry return. No way to tell without opening ceiling. You are not a magician. You can't diagnose/fix something that you can not access. And make sure that you are clear with the home owner that he needs to pay to get into the rodeo. The fact that leaks showed up after the boiler install, does not mean that you need to fix for free or for reduced rate. No way, no how. Best of luck.