I was asked to repair and update an old burned out stove last year. It was over fired bad. I removed the bad steel and welded in new. I also installed an air wash and secondary air with a baffle, full air controls, door gaskets, and heat shields for reduced clearance. It turned out nice, but his insurance company would not let him install it because it was not ul listed. (He had informed me that they were ok with it when I started the project) Here is a video of it with only 5 ft of pipe and some cardboard and bark for a test burn. The firebox was not insulated yet. The burn time on a couple handfuls of bark was over an hour. The stove temp was 475 pretty much the whole time.