TL;DR: The Ultimate Off-Grid Heater A **Rocket Mass Heater (RMH)** is an ultra-efficient wood-burning system that consumes 75–90% less wood than a conventional stove. It achieves this through **Complete Combustion** in an insulated "Heat Riser" and **Thermal Storage** in a large masonry mass (typically a cob bench). By the time exhaust leaves the building, it is often just water vapor and $CO_2$ at temperatures low enough to touch. This is the gold standard for long-term surv