My brother has had a PE Summit for years and uses combustion air from the room it sits in. When I installed my PE Summit in Washington State I was told I had to pull air from an outside source instead of the inside air. When I say outside source it isn't exactly the case. I ran a bendable 4" aluminum vent tube from my stove location up thru the wall behind it into the attic space(done during construction) . I tied it with wire near the peak of the roof in the attic to an 2x10 which was part of a truss. Put a plastic screen type thing on the end to keep critters out. I have a 6/12 pitch roof so have major area in my attic. The attic end is however about 20 feet above where the stove sets. My draw seems to be ok but does not seem as good as my brothers coming from inside air(he has no building restrictions). My question of you all is: How many of you pull air from the inside without any problem. Guess the fear is that all the oxygen will get sucked out of the house. I have been considering trying inside air to see if I can notice a difference. Think state law requires outside air in many states. Appreciate any feedback you could offer. Thanks.