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Leaky 1/2" PEX Fittings

castover Member Posts: 17

OK Pros,
I've got an in-floor heat system installed 10 years ago that uses 1/2" PEX. The manifolds that serve the 1/2" PEX that go to and come from the floors have had leaky compression fittings ever since they were installed. The manifolds were all corroded and scaled up, so I (the amateur) bought new manifolds and installed them. Take a look at the photo of the compression fittings. After I Installed these fittings all four leaked like they did with the pros. I had tightened the nuts arm tight as I didn't think that with only 12 feet of pressure it would take much. The 1/2" PEX is Rauplex from Rehau:
  • Should I be tightening the nut until it squeezes the ferrule and stops turning?
  • I was surprised how loose the part that fits inside the PEX was. I thought it would take some pushing to get it, but it almost seemed to have some clearance. Could that be why it leaked for the pros too? Is the tubing not the right size for these compression fittings?
  • When I was turning the nut something was grabbing the PEX and twisting it around. That doesn't seem good. Any way of not twisting the bejeebers out of the tubing?
Thanks Guys!