I was getting a nice fire going before I left for the gym. It was stacked pretty well. I waited about 45 minutes and it got up to 600, and started to pull back the air. Waited another 17 minutes, pulled it back a little more (slightly over half closed) while the temp peaked at 650, and then I left as I thought it was going down in temps. I left and my wife came home 30 minutes later to see the fire at over 800 and quickly closed the air completely. Lesson learned. Nothing looks to be warped. Made me nervous....So much to learn!!