Leaky 1/2" PEX Fittings

castover

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!

Zman

It looks like you may have wrong adapter for the tubing you are using. What info do you have on the manifolds?

kcopp

what brand pex is it?

Steve Minnich

On Rehau, tighten the nut a half turn past hand tight. Be sure to use a back up on the manifold nut (flats).

Steve Minnich

Like so.

castover

Stephen, thanks for the instructions. I'll try it again with a back-up on the manifold. So, are the compression fittings all pretty much standard or should I try to buy some Rehau ones? This is the source of the fittings I used:

http://www.pexuniverse.com/ssm102-steel-radiant-heat-manifold

Steve Minnich

I would use Rehau fittings. Some may disagree.

Steve Minnich

I'm a bit of a purist. I like using Rehau fittings with Rehau manifolds and Rehau tubing. Same for other manufacturers.

castover

Will these fittings:
http://bostonheatingsupply.com/rehau261007-101.aspx

Work with this manifold?
http://www.pexuniverse.com/ssm102-steel-radiant-heat-manifold

I'm trying to be a purist and use compatible equipment.

Steve Minnich

Yes, it should. The R20 manifold thread is standard. It looked like the ends of your Raupex tubing was twisted and maybe scored. The tube should be uncontorted, cut square, and without scores.

castover

OK Good, I'll give it a go. Don't worry about the scores. That's the piece I cut off to get a nice new piece for the fitting to attach