3/8" Pro PEX Connection Issues

tomtech

I recently completed rough in of 2 residences using 3/8" Mr Pex tubing for the first time. After several weeks we went back to air test the systems before final flush and fill. I experienced roughly 80% leaking fittings (3/8" only all other fittings were leak free). I am using Uponor Pro Pex Rings (Mr Pex does not make these), Uponor brass Pex fittings, Uponor EP Manifolds, Milwaukee Pro Pex Expansion Tool with Milwaukee Pro Pex Auto Rotate Expansion Die. We tested the system at 35 PSI as recommended by Uponor for the EP Manifolds.
I attempted to fix the leaks through heating the connection/fitting. I tried to do this at various levels of heat. This approach was not successful until I heated the fitting until the Pro Pex Ring turned clear as is typical for fixing a kink. In the installation we did have to expand the Pro Pex Ring one time to get it on the tubing (uponor notes this as a possibility in their install manual), and then expanded the assembly 5 times to fully set it on the die. I did notice that expanded assembly fit quite loose on the brass fitting and therefore we applied a small amount of heat (hot air gun) to facilitate the setting time.
We have made literally hundreds of Pro Pex connections on all sizes of PEX and probably experienced a leakage rate of less than .01%. I did call Mr Pex tech support to discuss this issue and they could not suggest or recommend any thing differrent to our installation practice and that they had never heard of this problem before.

Has anyone else experienced this issue or can anyone offer some resolution?

GroundUp

Are you 100% positive the tubing is 3/8" and not 1/2"?

tomtech

100%, Mr Pex Pex-a tubing w oxygen barrier 3/8" 100 psi w the proper ASTM spec numbers

tomtech

I was incorrect on the expansion times to fully seat on the die, The assembly was expanded until it was fully seated on the die an estimate of 8 expansions. This may have over expanded it and may have caused the issue but I am not sure.

mattmia2

Was the expander rotating properly? Some pictures might help. It may also help to carefully cut one open and do an autopsy.

ChrisJ

The only thing I found odd about 3/8 was Uponor says you have to expand the rings slightly before putting them on the tubing. Other than that I see no special notes.

It says when using the electric tool there should be 8 expansions.

Larry Weingarten

Hi, Have you contacted either Uponor or Mr. PEX about this? In looking through the Mr. PEX catalog, I see they only have expansion rings and tools down to 1/2", yet they make the 3/8" tube. How would they have you join it if you used only their parts?

Yours, Larry

tomtech

As a follow up. We tried minimally expanding the ProPex rings and redoing the connections.... that did not provide a solution as we still had minor leaks. Our tested solution was to go to crimp rings and fittings on the tubing connections and go to compression fittings on the EP Manifold connections.

As to the autopsy suggestion we did cut several of the leaking connections apart and could not find any burrs or knicks on the brass fittings and the profile of the expansion die on the tubing conformed to what is presented in Uponor's manuals consistent with the required rotation of the die.

I am quite surprised that no one else has experienced any of this.

ChrisJ

tomtech said:

As a follow up. We tried minimally expanding the ProPex rings and redoing the connections.... that did not provide a solution as we still had minor leaks. Our tested solution was to go to crimp rings and fittings on the tubing connections and go to compression fittings on the EP Manifold connections.

As to the autopsy suggestion we did cut several of the leaking connections apart and could not find any burrs or knicks on the brass fittings and the profile of the expansion die on the tubing conformed to what is presented in Uponor's manuals consistent with the required rotation of the die.

I am quite surprised that no one else has experienced any of this.

Are you 100% sure the fittings you used are correct for expansion connections?

How popular is "Mr pex" ? This is the first time I'm hearing of the brand.

mattmia2

Are you sure that Mr. Pex's 3/8" and Upnor's 3/8" are the same size?

hot_rod

Mr Pex, Tomas, actually pioneered PEx tube, started Wirsbo in the US back in 1984. That tube should be fine with the cold expansion fittings.