Pex and Sunshine

Ravenwoods

Rehau says not to expose their pex with the oxygen barrier to sunshine for more than 15 days. How exactly does sunshine degrade pex? I have a length of  Rehau pex 1.25" about 15 feet long that has been outside for three summers (we don't get much sunshine in the winter up here in Fairbanks, Alaska and the pex was covered by snow) that I had intended to use in a few weeks. But if the oxygen barrier has been ruined then I better not use it. But if it just degrades the pex, I might use it since it will be in an accessible area where I can easily replace it if it causes problems.

kcopp

Its the UV....

radiation. UV will damage almost anything if left there long enough.... Is it worth the risk of having to do the job all over again? or worse have a burst/ failure that makes a big mess? kpc

meplumber

well put kcopp

my colleague is dead on.  the uv rays make the pex brittle.  a couple of thermal cycles and you could have a mess on your hands.

TonyS

I left a manifold out

on the north wall of my house for maybe 6 years. It was for snowmelt that I had installed in my porch, right before the price of oil started to go ballistic.I left it there with the air gauge and never connected it. After about six years I realized it was never going to happen so I decided to remove the manifold. Being on the north wall this piping never saw direct sunlight. As I unscrewed the manifold from the wall, the whole thing, 8 pipes snapped off like a bunch of stale pretzels.

I dont use it for water pipe because I saw firsthand what happens to it.

Bury it and keep whats is exposed insulated or covered.

Ravenwoods

Information from Rehau

I just got off the phone with Rehau. They say the Ultraviolet light does not damage the oxygen barrier. It only damages the pipe and makes it brittle.



Up here in Fairbanks, Alaska, the sun never gets high in the sky and so the ultaviolet light is much weaker. I've decided to take my chances and use the pex, but I'll isolate it with valves in case thee is any trouble. It is not a crucial part of the system and can be closed off if the pex fails.

Mark Eatherton

10 years after...

Not the band, the failure of PEX in direct sunshine...



I had a VERY small piece of PEX on a snowmelt system in Silverthorne Colorado, that inadvertently had worked its way to the surface, unseen, and was exposed to direct sunshine on the East side of a building. It took 10 years to show in the form of a leak. If it had been on the South side, it probably would have manifested itself sooner.



It looked like fractured Marble.



I am also doing some long term exposure testing on numerous other manufacturers up at the High Altitude Research Solar Habitat (HARSH) Environment but they've only been on line for about three years. ;-) The only thing currently marbled up there is the steaks...



EDIT: Added picture of failed tubing. Bottom is the exposed tube. Top is a tube that was exposed to extreme stress (think tectonic plate movement...)



ME