Rocket Mass Heaters and Ianto Evans

I just finished reading what is probably the original Rocket Mass Heater book, “Rocket Mass Heaters Third Edition” by Ianto Evans and Leslie Jackson.

In case you haven’t been a RMH geek for a long period of time you may not know that Ianto Evans is regarded as many as the “Father of Rocket Mass Heaters”, at least that is my understanding. Ianto has been working with fire, building stoves and working with associated natural building techniques like cob, for decades. The biggest current names in the RMH field, like Kirk “Donkey” Mobert, Ernie & Erica Wisner, Art Ludwig and Paul Wheaton have all collaberated with Ianto, taken classes from Ianto or used Ianto’s designs as the basis for advancements in the science (or perhaps art) of Rocket Mass Heaters.

Rocket Mass Heaters Third Edition is not a long book, it’s only about 120 pages but it is packed with information, pictures, drawings and case studies. The book goes into exactly what makes a Rocket Mass Heater tick, how to build one and what materials to use. Rocket Mass Heaters in a nutshell consist of several main parts: The Burn Tunnel, Heat Riser, Feed Tube and the Mass or Thermal Battery and the exhaust pipe or Chimney.

One note of caution that comes up again and again in the book and should be noted by anyone thinking about building a RMH is that these heatersĀ  burn HOT. A typical wood stove will usually burn around 500 to 700 degrees Fahrenheit, the relatively low temperature is what makes them so dangerous, they don’t burn hot enough to burn off all the creosote and gasses and the typical temperature exiting the chimney can be in excess of 300 to 400 degrees. In a Rocket Mass Heater the temperatures in theĀ  burn tunnel can reach 1500 to 2000 degrees. That is hot enough to burn creosote, smoke and anything else that can cause a problem and the typical exit temperature at the chimney is around 150 to 180 degrees – much less likely to start a chimney fire. The high temperature burn is what make them so efficient but anytime you are working with fire pay attention!

The book starts out with a description of what a Rocket Mass Heater is, how it functions and outlines what they are and what they aren’t. It’s pointed out if you are looking for a “throw some wood in and leave for the day” fireplace then a RMH is probably not for you. The middle section of the book discusses in detail how to build a RMH, what kinds of materials you can build it with and the care and feeding after you have it built. The final section covers safety precautions, case studies of actual RMH builds and information on additional resources.

At $20.00 this book is a must have if you are interested in Rocket Mass Heaters or just want to read about cool things you can build that involve fire. I highly recommend it.

 

 

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