I’ll have to disagree with that. Many people, including myself, have found that the better PVC with the higher ratings is not significantly more expensive that the lower-quality stuff, and the thicker pipe means fewer breaks and other problems over the long run, so that small initial increase is earned back very, very quickly. When I do find PVC used as TPR drain pipes, it’s always the better grade stuff with the higher temperature and pressure ratings. And there also are many jurisdictions in my area that have no problem with PVC for TPR drain pipes under the premise that the drain pipe doesn’t have to take the pressure and/or temperature for an extended period of time since it has an open end.
CPVC (melon or tan in color) is rated for 100 psi at 180 degrees F.
PVC (white in color) is rated at 73 degrees F. (not sure of psi)
The TPR on my water heater is set for 150 psi and 210 degrees F.
Yes many jurisdictions allow CPVC. I just feel it’s better and safer to install copper for only a couple monkeys ($) more. After all, what is the price on safety?
I simply picture a noodle in boiling water when it comes to plastic and high temps.
In a quick trip outside in the pouring rain and 30 mph winds to my irrigation pile, I found Schedule 40 PVC rated at 125 psi, 310 psi, and 600 psi, and temperature ratings from 73°F to 210°F. The higher psi rating goes with the higher temperature rating.
Many jurisdictions here allow both PVC and CPVC, irregardless (love that word) of color.