Submission + - Rocketing Toward Efficiency: Paul Wheaton Explains Rocket Mass Heaters (richsoil.com)
Wheaton’s piece covers the combustion physics behind “rocket” burn tunnels, the role of thermal mass in holding heat for long periods, and practical considerations for anyone experimenting with a design. He also highlights the differences between codeapproved systems and the more experimental setups that circulate in homesteading circles.
If you’ve ever wondered why these heaters use surprisingly little wood, how they achieve such clean burns, or what sorts of builds normal people are constructing in garages and backyards, his overview is a solid starting point.