Bob, the vent for yours and mine is in the top of the roof. So there is a straight shot out the top for the heat to escape. The problem with the refer in the slide is that it has to vent out the sidewall. I guess that restricts a smooth flow of hot air for venting. I am with you, we don't get a bunch of frost, defrost seldom and have all the cold we can handle.
Peace
Dave
Peace
Dave