Where are you Doug? We are developing shippable cores and complete shippable rockets you just add mass to. Currently the best way to get one of ours is to come do one of our two day workshops and take a rocket home with you. For more information see the end of this
thread https://permies.com/t/80/31100/Rocket-Mass-Heater-Shippable-Core
I have used a dragonheater for several years now in part of my house, a Liberator Rocket Heater in one of my cottages, one of my own design in the other side of the house and in my rental and others I've built in a friend's school bus, several greenhouses, and the library at my kid's school. If you are near Cleveland come visit us. If not then watch for us at the Mother Earth News Fairs or join us at the Homestead/ATC
workshop at Paul's in Montana in July and build one to take home.
https://richsoil.com/atc.jsp Tell them Uncle Mud sent you.