I want to install a horizontally vented natural gas unit heater in my basement. But assuming that I am not misunderstanding, it seems that on the outside, the venting has to protrude a certain distance beyond the exterior wall. That won't work for my situation, not just because it will look like crap but because the exit would be 4 or 5 feet above grade, creating a physical obstruction when I walk by. There must be a direct vent unit which only requires venting with a limited protrusion -- is there?