"Pex doesn't insulate as well as PPr (thinner wall) and the fittings always introduce flow resistance and produce turbulent flow since they go into the pipe."
Errr, i have used systems of pex with outside fittings forever. Yes, inside fittings suck. All of the manufacturers have been sued for leaking, etc.
"Copper water pipes should always be insulated with at least 6 mm EPE sleeves or closed cell elastomeric foam sleeves (better). Even cold water pipes should be insulated at least in heated or high humidity spaces because of condensation that forms on the pipe."
Yes, they should.
But they very rarely in my experience (or they did a super shitty job) are unless the house was just built and you had a good code inspector
Errr, i have used systems of pex with outside fittings forever. Yes, inside fittings suck. All of the manufacturers have been sued for leaking, etc.
"Copper water pipes should always be insulated with at least 6 mm EPE sleeves or closed cell elastomeric foam sleeves (better). Even cold water pipes should be insulated at least in heated or high humidity spaces because of condensation that forms on the pipe."
Yes, they should. But they very rarely in my experience (or they did a super shitty job) are unless the house was just built and you had a good code inspector