PEX slack & loops

Can PEX be used for the vertical run of a shower stack (between the mixer and bolted-down fitting), or does it expand/contract too much to ever safely use it for any distance that's not long enough to loop?

Likewise, for 1/2" PEX, what diameter should the loop be for a ~10-foot run? If the sink and toilet are along that 10-foot run, do I need a loop between every fitting, or can I get by with a single loop along the 10-foot length, and a curved arc from each Tee to the point where it exits the wall?

Pex up to the shower valve is okay (if you size it properly), but it may not be the best after the valve. Pex, copper, and most things expand and contract. You just don't want the stuff stretched tight like a banjo string. A little slack is all that is required - no big loops needed. PVC and cpvc expand and contract much more than pex does, and on long runs, needs special consideration.

Loops are more critical on long runs. The most expansion is caused by heat.

Up to shower is ok, but down to tub filler is not. I've read that in several places from various mfg.

I put loops in my pex runs for the hydronic heating system. That runs 160-180degrees and the expansion is very noticable. On the hot/cold for potable water any expansion isn't nearly as visable.

OK, another PEX question... my bathroom has steel-framed walls. The old PB pipe was sheathed with what appears to be slightly larger-diameter plastic pipe of some kind (maybe gray electrical conduit, maybe larger PB... it's 25 years old, and covered with sprayed-on urethane insulation, so it's hard to tell for sure) where it passed through the holes in the steel studs. I assume PEX needs protection, too... so, what should I protect it with? Plastic pipe like the original PB? Maybe even the same pipe that was used to shield the old PB? How about the plastic rings they sell in the electrical department that snap into the holes?

Also... something's been bothering me badly since I bought the PEX this afternoon. I bought a roll of white PEX from Lowe's, but I bought the red PEX from a plumbing supply store (Lowe's was out of red). The thing is, they kept their rolls of PEX in an area that wasn't air conditioned, and was exposed to indirect sunlight. It wasn't in front of a window or anything, but at noon there was enough light in the side room where they stored it to read by. I remember reading the warnings about PEX and sunlight. Should I be worried? Is PEX kind of like unexposed film, where just carrying it unshielded across a parking lot and driving home with it exposed to sun will cause permanent damage? Or is it really just a case of, "don't install it where it will be exposed to sunlight, because after 10-20 years of daily exposure, it'll eventually start to leak?"

http://www.pexsupply.com/Viega-55140-1-PEX-Suspension-Type-Tubing-Hanger-12442000-p

UV is an issue with long term exposure. That being said I'm not a fan of the **********s not storing it correctly. The pex I get from online or the plumbing house is either in a box, or the coils are stored out of sunlight.

I've seen the coils in black plastic wrap lately at the Home Centers. Prob bc of the UV issue and knowing they can't leave it to them to make sure it's stored properly.

I store my extra coils in black contractor bags in the basement

sun

UV rays flow in a straight line. If the sunlight is not directly on the PEX, it is not getting the radiation.

sun

UV rays flow in a straight line. If the sunlight is not directly on the PEX, it is not getting the radiation. And

sun

UV rays flow in a straight line. If the sunlight is not directly on the PEX, it is not getting the radiation. And a "busy" supply house would not have any given roll of PEX in stock long enough to suffer any ill effects anyway.