I'm retro-fitting my Astoria pellet stove to the original 8" wood stove pipe that goes through the ceiling in my great room. I know the pellet stove won't get as hot as the wood stove did, especially after it goes from 4" to the 8" before it goes through the ceiling. When I look up into the opening, the fiberglas insulation is about 12" away from the existing 8" pipe. I guess I have 2 questions....can I add more insulation back around the pipe next to the rafters? And if so, can I use the 3" air space specified in the Avalon owners manual? I'm also considering using some Great Stuff spray foam to seal up the roof flashing (I can see small amounts of daylight coming through around the edges)...good or bad idea? Any thoughts on these issues will be a great help.....thanks in advance!