Ok, so I have finally decided upon an AC unit to put in the AS (Atwood 13.5). From what I can tell from the intallation manual, the apeture needs to be 14" square. Below is a shot of our central vent where I want to mount it. Outside dimensions of the vent are 14" but how does one get around the rounded corners? Do I have to cut the hole square?
On another note, about 16" to the aft of the vent, there is a little 1" diameter aluminum pipe sticking down through the ceiling (acutually roughly flush) with some odd little bob in it. What the *^(* is this?