Hi everyone, new guy here. I just started burning wood this year and i love it! I have a Century Heating "Whistler" wood stove. I have a through the roof installation. I have single walled black pipe going from the stove to the ceiling box then Super-Vent double walled insulated twist lock chimney pipe from there up. Everything works great, awesome heat! Im really paranoid so i clean my chimney out once a month. Well i cleaned it out last night and what i do is take the black pipe apart from the stove to the ceiling and clean those peices individually then run my brush up through the chimney. Well i noticed last night that inner wall of the double walled pipe sticks inward at the seam. The seam of the inner wall looks like the snap together type like the black pipe is. Well it almost looked like i could see in behind the inner wall at the seam and see the insulation. Is it normal for the seam to pertrude inward, and is it hurting anything if the really hot air gets in behind the inner wall? i would think that after a good daught starts that it would be pulling inward, not letting anything in behind. Any thoughts?