Lou - those heaters/vents are more and more common here in VA. They do not allow them to discharge beneath windows, doors or decks, and if to the side of windows must be 6’ away and above the window level. Also, Michael’s screen comment is right on - here the plumbers install a special end cap which has a small lip inside for the mesh to reside. Often I do not see the mesh and suggest it in the report (same goes for High Efficiency Condensing Gas Furnaces - PVC vent terminations with a lip for mesh…)
Sorry, I just looked at your pics and the lip is there on the termination end. Also, inside, is that disimilar metal contact oxidation or a pin-hole leak clogging itself with minerals? I see some funky build up… Here they require 18" of copper betwen the heater and the CPVC. I have never seen galvanized used! Different strokes for different states… or something like that.