The winter of 2013-14 was particularly harsh where I live in Cleveland, Ohio, but we managed to keep warm AND keep our fuel bill around $100 for the whole winter, mostly thanks to these amazing Rocket Mass Heaters we built out of cob and scrap metal. A local Fire Chief describes the design as "the first non-suicidal wood stove". Originally developed by Ianto Evans of the Cob Cottage Project, the RMH is a small insulated firebox and chimney that burns small scraps of wood nearly completely, resulting in super hot (around 1200 degrees F) clean exhaust that can be run through a radiator or cob bench to store the heat for slow release overnight. There is no creosote to cause a chimney fire and very little smoke. When the exhaust leaves the house it is about 170 degrees and smells like a dryer vent rather than a smokestack. RMH innovations continue. DragonHeaters offers precast RMH cores. Erica & Ernie Wisner offer plans for several highly refined and tested DIY designs. Uncle Mud has built several heaters for specialized uses such as to heat a school bus, or a greenhouse, or my barn. Feel free to contact us if you have questions.