This is the 'fall' issue I mentioned previously. There's supposed to be 3 inches of 'fall' for every 12 inches of horizontal run. This is half of that. I spoke to the engineers at the manufacture and while they were ok with this, they told me this particular unit was never meant to be installed in this type of design. The front of the fireplace is supposed to be flush with the finished wall and there can be no more than 4" of "overhang" at the front of the unit. i.e., just a small recess for a TV above the front of the unit. I was told this installation could cause the unit to overheat.

Great. You'd think the fireplace shop would have known that, especially since I shared designs with them from day 1. Grrrr...