Cindy: What material is used to cast the “Dragon heaters” combustion chamber? Is this suited for D.I.Y.? Or is this secret? I would understand if the recipe is not public. There was probably a lot of work necessary to find it.
permaculture is largely about replacing oil with people. And one tiny ad:
Morgan Superwool Plus non-ceramic fiber blanket for Rocket Mass Heatershttps://permies.com/t/153507/Morgan-Superwool-ceramic-fiber-blanket