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cast iron rads

keith_27
keith_27 Member Posts: 64
in THE MAIN WALL
what type of pex to use to hook up a couple of rads on a older hot water system. and can the brass pex fittings be used ??? The boiler is large enough to handle a couple additional rads.

Comments

  • Leon82
    Leon82 Member Posts: 684
    O2 barrier.
    Depending on how they are piped, you don't want to create a restriction with the size
  • keith_27
    keith_27 Member Posts: 64
    they are small rads so would use 3-4 pipe
  • Ironman
    Ironman Member Posts: 7,555
    Water takes the path of least resistance. If the new pipes aren't proportionately sized with the old ones...you get the picture.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • keith_27
    keith_27 Member Posts: 64
    the other rad are piped 1"
    iron pipe
  • mikeg2015
    mikeg2015 Member Posts: 1,194
    You can use smaller pipe, but you may need to change the pump size and re-balance the system.
  • Ironman
    Ironman Member Posts: 7,555
    keith said:

    the other rad are piped 1"
    iron pipe

    I'd recommend that you use that size to the new rad's too. Again, the key thing is keeping the piping PROPORTIONATELY sized the same. If the existing pipes are over-sized, then the new ones must also be.

    Putting a larger circulator in is most likely unnecessary and wouldn't compensate for smaller piping because the flow would simply follow the path of least resistance through the larger pipes.

    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
    Canucker
  • NY_Rob
    NY_Rob Member Posts: 1,370
    Keep in mind that 1" PEX is not the same inside diameter as copper/iron pipe... and to make matters worse... the PEX fitting go inside the PEX restricting flow even more. You'll probably need 1.25" PEX to equal the ID of copper/iron pipe after fittings are installed.

    Probably better off going with 1" copper or iron...

    Ironman

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