We have a VC Defiant non-cat stove in a room with a 10 foot ceiling. The chimney is an uninsulated 8 inch round steel pipe up to the 10 foot ceiling and then it goes through the ceiling and roof with an insulated double (triple?) walled ss pipe another 8-10 feet. The chimney cap is not above the roof ridge, but it is probably 12 feet or so away from the ridge. We are in West TN. The stove burns well and draws good until it has been throttled down for the night by closing the air intake lever. Sometimes, an hour or two after the fire has been put to bed for the night the stove will begin getting little dancing wisps of fire in the firebox as if it is getting only enough oxygen for a tiny fire. It is almost certain that he stove will have a little explosion and puff smoke out of the griddle/lid. I am sure that the firebox in the stove is operating correctly, BUT, I am not sure if I have enough draft when the stovepipe cools down and/or the stovepipe is too large to keep a good enough draft going. The problem seems to be much worse if we fill the stove with new wood right before bed. It seems that the heat cooks some volatile gases out of the new wood and then it has a tiny explosion. It does not seem to backpuff if there is pre-charred wood in the stove. My friend down the road has a VC Encore non-cat with a 6 inch insulated pipe exiting its entire length up through a masonry chimney with about 25 feet total length. He never has any drafting or backpuffing issues no matter how he adjusts his air intake lever. I would like to correct the backpuffing issue. It seems as if I have the following choices: 1) extend the 8 inch insulated pipe another 3 or 4 feet. 2) build a wooden "fake" chimney around the existing pipe in order to insulate it better. 3) Reduce the inside diameter of the 8 inch pipe by putting another liner inside of the current pipe and reducing the inside diameter to 6 inches in order to create more velocity. I am not sure if that would be "code friendly". 4) replace the entire 8 inch system with a 6 inch system to try and create more velocity. 5) install an outside air kit (OAK) in case there is some sort of negative pressure issue that I am not aware of. My goal is to be able to close the air intake lever completely down when we go to bed and not have to worry about backpuffing. I did a search of the forum and never found this exact problem discussed. I did see some discussion about larger pipes not drawing as well as smaller pipes and insulation being very important. The VC defiant is approved for a 6 inch pipe unless you are burning with the doors open, which we never do. Any help would be greatly appreciated.