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Heating piping embedded in concrete floor for 60+ years.

I recently inspected a split level house built in the 1950s that has baseboard heating in the upper areas, but there are two hot water radiators at grade level. The piping for the grade level radiators is embedded in the concrete floors. Since the system is original and more than 60 years old, I am concerned about degradation of the embedded piping, whether it is external corrosion from the concrete, rusting from condensation or some far out speculation of degradation if the piping could move while in the concrete. I know it is a stretch of the imagination, but thought I would ask anyhow.

Thanks for any advice.


  • Jamie Hall
    Jamie Hall Member Posts: 23,305
    What is the pipe material? Makes a difference... some materials (steel, copper) can corrode badly from the outside in concrete. Sometimes. Black iron, on the other hand, not much.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • SteamingatMohawk
    SteamingatMohawk Member Posts: 1,007
    I assume it's black iron. Good question.
  • Jean-David Beyer
    Jean-David Beyer Member Posts: 2,666
    edited October 2019
    My house was built in 1950 and has copper tubing (mostly 1/2 inch) in the slab at grade. As far as I can tell, the system is not leaking. I used to turn off the make-up water and watch the system pressure twice a day for a month, and do not lose pressure. The pressure gauge does indicate slight pressure changes with when the circulators run, and reflects the setting of the makeup pressure regulator, so I think it works. Come to think of it, I had to drop the pressure to add boiler treatment (X-100) and the gauge noticed that, by golly.

    I have been told (probably here) that it really depends on the mix of the concrete. I may have the details wrong, but IIRC, the more fly-ash in the mix, the faster the corrosion.
  • MrCofDG
    MrCofDG Member Posts: 40
    Hello Jean-David, the 'embedded in concrete' in the title brought me to this discussion... but after reading your comment, I'm curious - what prompted you to add boiler treatment (X-100) to your boiler system ?
  • Jean-David Beyer
    Jean-David Beyer Member Posts: 2,666
    what prompted you to add boiler treatment (X-100) to your boiler system ?

    I had an old GE oil-fired boiler. I wanted to replace the in-ground 1000 gallon oil tank before it started leaking. It turned out I was too late.

    But I replaced it with a natural-gas fired Weil-McLain Ultra 3 mod-con. After a year, W-M sent me a notice to put X-100 in it. So I did. X-100 comes with a test kit to see if you need to add more. Most years, I do not need to add more, You can get test kits without buying the additive itself, so I do.