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Fostapex with SVC fittings

Robert_H Member Posts: 140
I'm connecting 1/2 fostapex to a viega stainless manifold using viega SVC fittings. the fostapex outer layer does not fit in the the threaded collar of the SVC fitting and must be cut back. I used the the viega prep tool but that only trims back about a half an inch which is not enough. experimenting with a piece of standard pex it seems like I should be trimming back about an inch of the fostapex.

To trim this back "by hand" seems like asking for trouble.

How do the pros do it?

Im at the end of this installation and don't want to rush but I found nothing on this in any of the viega instructions.




  • kcopp
    kcopp Member Posts: 4,392
    use the...

    Fosta pex tool that comes w/ the crimpers.

  • hot_rod
    hot_rod Member Posts: 21,844
    same issues with TRVs

    that use compression fittings. You need to strip back more of the outer jacket.

    I tried to modify the prep tool and did get a bit more "bite"

    Another method I tried was a slight cut around the jacket with a tubing cutter, just enough to score the outer jacket. Then you can peel the extra material that the prep tool doesn't reach.

    It is a slow tedious process, seems like and extended cut tool would be a simple fix from Viega?? A machine shop could build one fairly easily, I suppose.

    It's a great tube for many applications, especially retro-fit work and "quiet" dry radiant installations, one simple tool modification could make it a lot more popular with customers.

    Time to fire up my old engine lathe :)
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Robert_H
    Robert_H Member Posts: 140
    Thats the tool Im using

    but it only cuts back about 1/2 inch which doesn't seem like enough. To assemble the fitting I have to drop the ferrule down into the fitting and then slide the trimmer fostapex into it. kinda bassackwards to me.

    I'm going to try again this afternoon. I think last night by the time I got to it I had dealt with too many problems to look at it intelligently :O

  • ChrisL
    ChrisL Member Posts: 121
    Manifold fittings

    I was able to get the tube to work on a r20 fitting with the normal prep tool.  I threaded the nut onto the manifold, while pressing the tube to take up the slack as the nut tightened onto the manifold.    Not sure if it will work with what you are using, but it worked for me.

  • Robert_H
    Robert_H Member Posts: 140
    Got it!

    It works fine with the cut back provided by the standard prep tool. its just a more compact operation than with regular pex and you are a bit in the blind. Once I sorted it out it took me about an hour to hook up all 14 ports.

    Thanks All!