Pex in cold weather.

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you could go with a type of plastic pipe called wirsbo it will expand three times it normal size without bursting and then return to its normal size once thawed price is competitive with pex just cant be in direct sun light and normal rings and crimpers will work
 
If I am not mistaken, it is the connectors that usually end up bursting when dealing with PEX. I have no personal knowledge of this, but many plumbers in the mountains have mentioned it to me.
 
There are different 'types' of Pex tubing (A, B, C). Pex A (wirsbo) will expand as stated earlier. I'm in Oregon and we use Wirsbo for most residential applications and I've installed up to 2" Wirsbo in really cold weather, it's harder to work with and it takes longer to shrink back on the fittings. Using a torch lightly on the rings will shrink them quickly so you can turn the water on sooner. I've yet to see or hear of Wirsbo freeze breaking but I'm sure it can happen under extreme conditions. The fittings and collars(rings) are the weakest link in the Wirsbo System. Rehau is a great product as well, expensive though.
 
Also, I used to work for a small resy company who used "RTI" or "Zurn Pex". It's a quick to install system but we had several issues with the crimp rings. Sometimes the broke or didn't crimp right. Not to mention they are "insert fittings" and neck down the inside diameter of the pipe, creating a large restriction (friction loss). How they are legal...I can only assume they lobbied hard...$$$
 
I use wirsbo all the time I actually had a house freeze this year with it and the only leak was where the home owner used a torch to try and thaw the pipe they actually melted it, otherwise house was froze solid for a few days no wirsbo breaks
 
All pex pipes have a better expansion ratio then metal pipes. Of course Wirsbo is probably the best choice due to the fact that the product installation is based on contracting back to original shape. This is due to Wirsbo being a cross linked polyethylene product. As others have stated though, the fittings will definitely freeze and break in certain conditions. You should insulate the lines or where the weather is extremely cold, heat trace any exposed lines.
 
Pex will withstand freezing better than most......Just dont put your fittings close together......if you do the pex will not have enough room to expand and will/could fail.
 
Pex will withstand freezing better than most......Just dont put your fittings close together......if you do the pex will not have enough room to expand and will/could fail.

I would have never considered this, but it makes alot of sense!
 
wirsbo will expand better but the fitting are the weak point.
If you use any pex in a attic you should install it like you would roll copper under slab.
run your pex (wirsbo) ends down into a warmed wall and manifold them so no fittings would be prone to freezing.
another option would be to add a recirculating pump on the cold side so the water would ALWAYS be moving and less prone to freezing.
Hope this helps
 
when I say add recirc pump to cold side a mean you should ren system like you would for a hot water recirc system
with a check valve on the main to keep the recirculating lines contained to the loop only
 

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