I purchase a Corn Flame Energy Model 5000 back in November. I have had 2 Hopper fires since and now seeking advise on what to do. The Installation called for just using the 6 ' Flex Pipe provided to just reach the chimney liner. Wanting to be safer I instaled double wall 6" pipe all the way to the top(20'total) with a cap on the pipe and a chimney cap on the chimney. When the Hopper gets low, smoke starts to enter the hopper. I am using Wood Pellets and was told I could use Corn or Pellets. Anybody have suggestions, my wife says get rid of it.