We had a water heater fail today. I've disconnected it, but I can't identify the hot and cold water supply line types. They're red and blue plastic, respectively, but they have a metal layer completely enclosed by plastic inside and out. The metal layer is thin -- maybe 30 or 40 mils -- and may be more of a winding than a solid layer. I think I can see some overlaps. The metal layer is so thin that a PVC cutter can get through the stuff pretty easily.

PEX fittings don't fit. This stuff is in-between 3/4" and 1" PEX. PEX 3/4" barbs are far too small and the 1" barbs are far too tight, and won't even begin to start. The OD is 1" minus -- maybe dead-on 25 mm -- and the ID is 3/4" plus. 1" compression fittings, however, are too loose and can't grab under pressure. They slide off. There are faint markings that LOOK like "75ft MACHUSHEK 5187". The lines were connected to the water heater at both sides with crimp copper collars over barbed sweat fittings to the standard flexible hookup coppers. I had to disconnect the supply side because the cutoff valve was completely corroded and the shaft broke off when I was trying to close it. The crimp copper collars are nice and tight over the barbs... and they're much smaller than the PEX 1" Go-No-Go gauge and much bigger than the PEX 3/4" Go-No-Go gauge. If a PEX 7/8" existed... that would be the size. I held up a cut piece of the stuff to PEX at the hardware store -- sure enough larger than 3/4 and smaller than 1", with overall thinner walls, probably because of he metal winding.

My first goal today was just to close off the lines so I could use the water in the house while I secure a new heater and install it -- because of the new insulation standards I need to cut a door from the eves into a room upstairs -- so not a quick change. As I said, PEX barbs wouldn't work, and neither would a 1" compression fitting. What did finally work was forcing a 1/2" NPT male plug into the end of the tubing and threading it into place with sealing compound. Just for certainty I put hose clamps around the end, too. The resulting plug is water tight under pressure and clearly robust.... so I've got breathing room to cut and frame the door, pull the old heater, move in a new one....

At the second hardware store I visited one of the plumbing guys knew exactly where I lived and said some plumbers were refusing to work on homes with this stuff and were telling homeowners they needed to completely re-plumb with standard lines. That's way not cool. The house was built in late 2003.



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[www.wattsradiant.com]

sounds like pex-al-pex.

yeah, it is pex-al-pex tubing. they do make a wide variety of fittings for it.
compression fittings are available that require only a pair of wrenches to install.
search for 'pex-al-pex compression fittings'..



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Newmark used radiant heating line for the main plumbing lines? Gee whiz. Thank you both very much for the information. I'll track it down.



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it is the same pex inside. big difference is the aluminum creates an oxygen barrier which you need for heat but not for hot and cold water..

Clearly, the plastic part is the same basic material, true. I mean, that's what PEX stands for, anyway. I'm looking at Watts Radiant's site now. But it's much less plastic as compared to regular PEX of the same nominal size because of that aluminum. Thus completely different fittings....

Builder must have had a surplus of the stuff.

Thanks again. I'll get some compression fittings to standard NPT females FedEx in.