Standard furnace, combustion on bottom, heat exchanger up next, AC coil plenum, etc. But they set it up so it's counterflow....air flow is top to bottom, so in effect, it's the return air being conditioned. Also, the cabinet doors are backwards. I reinstalled then with the vented portion at the bottom to supply the combustion. I've never seen, heard, or imagined anyone ever doing this. Besides from the complete stupidity, what else can go wrong? It's so wrong I'm not even sure what that means or how to describe it..... Anyone ever seen this? Click to Enlarge 48.11 KB