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Plastic Piping in Steam System

Rob Pickard
Rob Pickard Member Posts: 20
I noticed that my 6-story condo building has sections of plastic pipe that are used as part of the water return line for the two-pipe steam system. It appears that these were added at some point to replace the metal ones that had been used.

Should I recommend that these plastic pipes be replaced, or are they fine because they should only be carrying hot water back to the boiler?


  • Ken_40
    Ken_40 Member Posts: 1,320

    That's a no-no. I suppose CPVC MIGHT tolerate over 200 degrees F - which would be common for a steam return, but here's what they wrote in their specs.

    CPVC piping which is suitable for hot and cold water distribution has a 400 psi pressure rating at room temperature, and a 100 psi pressure rating at 180 F."

    I suspect any sort of insurance or municipal inspection would result in a "red" tag failure notice and an order to stop using the system unti,l repairs are made. The obvious use of plastic in a steam system is from lack of knowledge, coupled with an errant "save a buck" mentality.

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  • FRANK_24
    FRANK_24 Member Posts: 80
    plastic pipe

    What happens when a steam trap fails and passes steam into the plastic pipe?? That WILL happen, I just don't know when. But it will happen in the winter, probably on a Saturday nite in February.....no service man available to replace piping then, shut down the boiler, freeze out the people living there, disrupt the whole building, make enemies out of neighbors, think about it. Get rid of the plastic....that stuff is good for drainage[period]
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