I am so bummed! I made a fatal error with my BGE that I will never do again.
After waking up early this morning to put my first brisket on the BGE, I returned home from church and I realized that I hadn't inserted a thermometer into the brisket. -- I hesitated to open it because it was so nice and stable at about 240F. Anyway, after about 4 hours of cooking, I opened the BGE and inserted the meat thermometer. After doing so, the family and I left for day.
Well, when I came back home after being gone for about 3 hours, the meat thermometer was chirping. Not something I wanted to hear when I was expecting another 3 - 4 hours of cook time. Apparently, when I opened up the BGE, the top air flow adjuster must have moved totally opened. So, for about 3 more hours, my brisket cooked at 550 F!
It was a hockey puck!