So, just bought a used Buck Model 91 (about 5-6 years old, but in good condition), installed it in my masonry fireplace and noticed a smoke smell whenever the blower kicked in. I know I've made a few mistakes with installation along the way, which I'm trying to rectify. Here's the full history: First, installed it with a steel chimney flue liner (6", because this would fit inside of the 8" square terra cotta flue tiles). Initially, I thought the smell was from a leak somewhere, but I haven't been able to find a crack (although I can't exactly see the top air cavity around the catalytic converter), then I had a revelation the other night when looking around with a bright light looking for smoke: I saw a fine line of smoke being drawn out of the air inlet (just below the front door and just in front of the blower intake). I closed the air inlet and pressed to seal it, and smoke smell decreased greatly. In retrospect, I did get smoke billowing out the door whenever I would open it, even after opening the shotgun for a few minutes. So, now I'm thinking the smell is at least partly due to poor draft, especially since I was decreasing the 8" flue to 6". I'm thinking of removing it and installing 8" flue to the base of the terra cotta tiles and removing the liner inside of the terra cotta, as they appear to be in good condition and would be about the right size. I had a much smaller / cheaper Century Heating insert I bought from Ace in the space previously, and never had any smoke smell (replaced with the Buck in hopes of heating the whole house). Am I completely off in thinking this way? Anybody else with a late-90s / early-2000s Model 91 have similar problems, this seems to be a design prone to backdrafting whenever the blower is on. Thanks in advance for your advice, you all seem to be a neverending source of fireplace knowledge.