This is the second time this has happened this week. Hearthstone Mansfield. One year old. I recently changed its location and "mounted" the OAK (I haven't finished the plumbing part yet. On a reload for the evening fire, I packed it full of seasoned elm. It was about 250-300 degrees on the reload, so I left the air closed down. An hour and a half later it was cranking at 700 degrees. This is the second time it happened this week. When I moved the stove, the new location of the chimney went through the roof at a lower point. I have a 6/12 roof, so I needed to add two feet to the chimney height. It sticks out of the roof 4.5 feet. Even so, the chimney needs another foot of height according to the installation instructions. It's about six feet from the ridgeline horizontally, but about six inches above the ridgeline vertically, so I thought I would test it out. Overall I have a 19 foot chimney. I thought installing an OAK may reduce the flow of combustion air. I see that I'm wrong. I know reducing the chimney height will reduce draft, but what other concerns would that create? My fear is overfiring the stove. It was a little over 700 for a few minutes. I turned on two fans and the stove immediately cooled and was down to 650 in 10 minutes. Now 30 minutes after peak it's cruising at 550-600. Any comments or suggestions would be helpful.