I am also making a sauna heater. Here is my plan. 4" feed tube, 3" burn tube, 4" heat riser. The plan is to basically make a Aprovecho except with rocks in the pot. I will have vermaculite around riser and in bottom tank. In upper pot area smoke will exit via chimney, rock pot will be sealed in upper tank with top open for water to be dropped on rocks. My questions are, the diameter of bottom tank is 12" so does that mean the riser should be about 36"? Seems like to get rocketry the legnth would matter. Do you think this will work for a sauna? Thanks for any insight.
