Does anyone know where the combustion air inlet is on this unit? I'm wondering if I'm leaking air up the chimney (I know the installers sealed the top of the chimney, not sure if they put a blocking plate or insulation around the bottom). The surrounds (I forgot which kind I got, they're black cast iron) seem cool at the sides. For those of you who have these, you can see that the sides of the surrounds have a space behind them for most of their height. If I put a match next to the side of the surround, the flame gets drawn back behind the surround, towards the fireplace opening. It's not a very strong draft (enough to bend a cigarette lighter flame, but not put it out, but enough that even with a good fire burning, the edge of the surround isn't much warmer than room temp). If the unit is drawing combustion air behind the surround, that would probably explain it.