Ok thanks...someone said you can not use pex between valve and shower head ..is this true ? I thought u cant use between valve and tub spout ..I did not know between valve and shower headI know that pro-press is rated to be installed on all grades of tubing that is rated for potable water: Type M, L and K. We only install press fittings now and use Type L for all of our installations.
Every piece of a plumbing system will fail eventually. Copper tube and fittings will wear out. Will the rubber o-ring seal that is compressed between the fitting and the copper fail before the copper? Dunno.
Here is a cross section of a propress fitting I removed from a project.
Is specified by upcRequiring K or L depends on local regulations. There are places that don't allow M for pressure piping. Others are fine with it.
I don't think that IPC or UPC specify this, but I easily could be mistaken.