On Thu, 21 Jan 2016 15:02:47 -0500, wrote:

My water heater has been plumbed with plastic for 30 years (white PVC
in, CPVC out). There is a short metal riser right at the stubs but it
came with the heater. I am not sure if it is a thermal trap or if it
holds the anodes.

Mine has PEX, copper, brass, rubber and galvanize nipples. Installed
it myself ~ 6 years ago.