Here is a video showing our experience with building a rocket stove thermal mass heater. It shows our problems and temporary failures, as well as our successes. The main difficulty, or what made a simple technology a little more complicated, was a particular innovation that my son, Noah, and I tried using an old metal mailbox as the wood feeding chute. We did that because we wanted to feed the fire from outside to prevent the greenhouse plants from getting too much smoke, in case of backdrafts, or any other possible malfunctions with the stove. That put the wood feed back about 10 inches to a foot further away from the heat convection barrel than what we have seen on most rocket stoves on the internet, which caused the fire and smoke to backdraft on us a bit for awhile. But, as you can see in the video, we came up with a solution and it worked just fine in the end.