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Pex-al-pex to pex

boulderz Member Posts: 31
I am extending an existing short radiant loop. The original loop is pex with O2 barrier. I have a bunch of pex-al-pex I want to use up, can I join and use the the two together?? What fitting would I use if possible?



  • hot_rod
    hot_rod Member Posts: 22,486
    What brand and size of tubes? Do you want a crimp type, or compression. How many?

    The crimp would be the least expensive if you can find the correct brands. Sweat a male adapter into a female to custom build a transition fitting.

    Same with a compression, get a pex and PAP nut and ferrule.
    We, at Caleffi make a universal fitting for both pex and PAP, build your own version for the tube size you have. It fits most all tube except some of the odd mm stuff from Europe, look for the number on the tube to identify what ASTM standard it was built to.
    PAP compression fittings use a brass ferrule to grip the stiff tube better, it is serrated inside and really cuts into the outer jacket of the tube.

    You might try Sioux Chief, they used to make transition couplings for PB to pex, maybe they have a pex to PAP.

    The PAP crimp fittings, shown here, often had o-rings to make a good seal inside, as the crimp ring with the stiff al layer presented a challenge.

    The fitting shown here was an old Weil Mclain fitting, I believe it was a Refing (sp) tube out of China. Many manufacturers use that brand and private label it.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • boulderz
    boulderz Member Posts: 31
    It is 1/2", pex Rifeng ASTM F876/F877 to PAP Rifeng ASTM F1281-2005. I really only need to join at 1 fitting, as the beginning and end of run meets copper.

    So no problem mixing the two and I should be able to come up with a fitting if I read correctly.

    If yes, that's great, I want to get it run and then will deal with the fitting later.