Would someone remind me if copper flex is acceptable at the TPR valve drain piping or show me a thread where this is discussed?
Not as in your application (Gravity drain only) and I note it and explain it to clients as possibly hindering the flow. But by the time the valve opens they have bigger problems to deal with. nice work BTW should go in the photo “Hall of Shame” 
Good point Barry…I got so hung up on trying to decide if the flex were proper that I overlooked the upward installation. If it were all pointing down would copper flex be acceptable? I think no, but I want to confirm that. I’m having either a senior moment or a brain fart.
Thanks Barry, yeah, I got so hung up on the flex that I didn’t even consider the upward loop.
Flex is allowed by some codes, but as Barry stated, uphill is no good.
I called Lanier.
What did they say? 
They said see Jeff Pope’s post on the MB 
My seeing eye dog caught the up-loop
What all trades people when an HI calls out a defect:
“Those who can, build houses. Those who can’t, inspect houses.”
“Those who can, build houses. Those who can’t, inspect houses.”
Tom, Don’t say that heard that twice this week and also “Those who can do those who can’t teach.”
Hate those sayings.
If those who build really could, we wouldn’t have to inspect!
“If those who built used their own keen eye, the ink in the inspectors pen wuold not run dry”