So I just installed the new Quadrafire 7100 a couple of months ago and was getting decent burn times but not what I was hoping. Kinda sluggish. Coughed it up to an inexperience with the stove. Then I noticed that the glass was getting dirty. Thought maybe I had wet wood. Went to my brother's house and used some of his 10 plus year, been sitting in the shed, wood. Burn times were no better and the glass continued to blacken even after some 700 and 800 degree stove top temp fires. Called my fireplace store and told them about my problem and they asked me all of the same questions, "burning with seasoned wood? Not chokin' it down too far are ya? What is your chimney height? None of this was the problem. To my surprise, they sent two technicians to my house, from Hearth and Home, and they were very helpful, polite, and knowledgeable. They determined that an interior firebox weld was missing on each side and that maybe my fresh air intake run was too long. I shortened my run and the glass was still getting black. They think that as the fire gets hotter, the delta T is pulling cooler air in by the door, at the missing welds, causing condensation at the door; soot. They are going to pay me to have a welder fix the problem. I have been very happy with the service but disappointed that this occurred in the first place. Special note to any 7100 owners, the technicians as well as the gal in the plant, admitted that this weld was being missed on the assembly line. This has happened to others. They do not know how many. I'll post on what comes of this.