I am about to remove my 5100i in order to properly install a much needed block off plate (thanks to all the helpfull advice I've received here). After reading through my manual again, I'm curious about the outside air plate mounted on the back of the stove. My fireplace has a hole in the back of the floor where a metal door once was for ash. I just have a large piece of sheet metal sitting on top of it. There is also a metal door on the back of my chimney in the garage which certainly isn't air tight. Should I leave the outside air plate on the back of the stove? Should I seal the ash removal door in the garage? Thanks in advance for any suggestions! My house is about 40 years old, 1700 sqft., and is by no means air tight.