Myself when I drain the water heater (like when winterizing) I replace the anode with a piece of screen. I do not leave the pressure valve open because I don't want the spring to loose strength from being compressed all winter.
Jake my sidekick (yellow Lab) 10/04 - 05/20
2017 RAM 2500 CC 4X4 Cummins Diesel
2016 Flagstaff 26 FKWS
AF&AM & El Korah Shrine of Idaho