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Piping with steel or copper

I was at my neighbors house last year and noticed he had a lot of copper pipe used in his mains and returns. I suppose for simple repairs. Anyway, recently I needed to add a radiator to a new addition and I figured it would be a lot easier to use copper rather than steel. I did the install and everything works great, but someone told me that I shouldn't have done that. Is there anything wrong with using copper instead of black pipe?


  • Andy_14
    Andy_14 Member Posts: 121

    The way I understand it. No copper for steam. Otherwise it's ok. But better wait for a pro to answer for sure.
  • Brad White_9
    Brad White_9 Member Posts: 2,440
    It depends

    but in a closed system, combining copper and steel piping is done all the time.

    Biggest issue is dielectric corrosion, essentially creating a battery using dis-similar metals in the presence of an electrolyte (water). The less noble metal (steel) corrodes as the copper is the more noble of the two... Sometimes dielectric corrosion is an issue, often not but it can be prevented by connecting the two metals with a bronze ball valve as an intermediary. (And an extra valve comes in handy, too!)

    One issue which could surface is where the existing system is a converted gravity system or still a bona-fide gravity system.

    Say you add a radiator to such a system and size the piping conventionally, maybe a 1/2" or 3/4" copper pipe which will carry between 15,000 and 30,000 BTUH (patting yourself on the back here). Trouble is, the rest of the house radiators have 1" and 1-1/4" runouts.... Without balancing valves or TRV's on all of the radiators, your new addition to the family becomes a red-headed stepchild... you will find out.
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