Mike, Douglas and Shawn.
Mike, my digital camera just broke! It is a 2.3 mp Toshiba. It took good pictures, but will cost more to fix then what it's worth. So I am shopping for a new one. 5 million pixel or more! Anyone have one they are really happy with? Let me know. I will post pictures as soon as I get a new one.
Douglas, the damper is not automatic, cool thought though. It is more like a manual slide that works kind of like a tool box drawer.
The duct is of boxed heavy gauge steel, vented through the roof. Exhaust from machine is also vented into the duct.
Shawn, I found that roof vents like you would find in a R.V., are a must to let heat off the ceiling. Also that you must crack a window or have a make up air vent to let the machine's engine breathe. I would like to wrap my exhaust pipe with racing tape and the stack with a heat rated duct wrap like Fire King etc... Thus cutting down on interior heat. I am lucky because my box also is air conditioned, with a Carrier unit that can also work as an air makeup system.