Just installed a P.E. summit insert. Got a good fire going with the door cracked for about 15 minutes. Shut the door put the lever to High and sat down. When I looked back at the fire it was out. opened the door and poof room filled with smoke and flames shot out the door. [back draft]. This unit was manufactured in 06. I bought it unused from a dealer this weekend.It was a display model. I have it some what apart now. Any suggestions. I will call the dealer if need be. I was hoping it might be an easy fix.