Here's the replaced T&P valve on the water heater. I believe it is right side down and installed correctly. It has been in for over a week and no discharge.
Interestingly, I had to get it at a plumbing supply house because the big box stores did not carry the eight inch thermometer T&P only the four inch. It was more expensive, $17 as compared to under $10 for the four inch. I needed the eight inch thermometer because that's what I was replacing. The hot water outlet exits the tank from the same coupling as the T&P valve which adds distance from the valve to the inside of the tank - thus requiring the additional length of thermometer.
I installed the white expansion tank horizontally from a riser because our water pressure is high at 79 psi and up. The picture is misleading by which I mean, the expansion tank is NOT attached to the hot water riser exiting the tank but from the cold water inlet riser just behind, and at this angle, in line with it.
All NPT (national pipe thread threads) couplings were taped AND doped.
Thanks Jim and Red. I couldn't have done it without your support. Nice to have hot water!