It's easy these days to get swept up in the rhetoric around AI or the crazed pace of the political seesaw... but fire has had a consistent place in human life for over 2 million years. The oxidation of biomass fuel which releases solar energy that has been captured by photosynthesis - a process commonly known as burning a fire - has been one of our primary methods for cooking and heating. While we are bound to this special relationship with our planet Earth, trees will continue their relentless impulse to grow and we have the opportunity to coexist and benefit from some of this growth as fuel for our needs. The responsible and efficient use of this resource is at the core of Firespeaking's mission. We see the efficient use of biomass fuel as one part of a larger hybrid strategy to meet our society's energy needs.
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As our work continues to get more technical, we try to keep in mind these simple goals.
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Read on for some product development updates, an interesting opinion piece on rocket mass heaters, and some global connections that we are excited about.
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We now have a sophisticated combustion gas analyzer (the ECOMD) and a 4 channel temperature reader connected to our shop unit and are looking forward to publishing results and analysis. We continue to work on our custom masonry heater design system and will publish more information soon.
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Are Rocket Mass Heaters ready for Prime Time?
This winter I spent time in a work group evaluating a proposal to include Rocket Mass Heaters (RMHs) in the ASTM Standard on Masonry Heaters which would potentially pave the path for them to be "permitted" in mainstream North American construction. I summarized my thoughts in this forum post:
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There is general consensus in the Masonry Heater Association (MHA) that rocket mass heaters should not be included in the current standard and that a new and different standard would be needed for this initiative to devleop. We are genuinely interested in others perspectives so read the post and consider contributing your opinion.
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Pictured above is a rocket mass heater we led the construction of at a MHA annual meeting which substitutes the normal barrel heat exchanger for a cooktop.
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Here is a snapshot of a Testo combustion gas analyzer's readings of this stove in action. The 85.5% net efficiency is at the very top of the range for woodstoves and comparable to the best pellet stoves which use a dramatically more refined fuel. Also note the stack temperature of 223.2 deg. Ferenheit. The fact that this is only slightly higher than the condensation point (212 degrees) means that just about every calorie of energy has been extracted for heating before the combustion gases exit the chimney. This exemplifies the rallying call: #nobtuleftbehind!
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Whatever the fate of RMHs in mainstream residential construction, there is no doubt that it is an important design pattern for a masonry heater builder to understand.
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To study this specific project further...
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Global Connections
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First, close to home, we continue to appreciate the work of The Alliance for Green Heat. They publish an informative monthly newsletter which provides updates on legislation, policy and innovation in biomass heating. In their most recent newsletter, they published an analysis by the state of Maine of heating costs by fuel per MMbtu.
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This analysis shows that the cost/MMBtu of heating with a modern efficent and low emission wood stove ($18.67/MMBtu) is almost half of that of a ducted heat pump system ($32.42/MMBtu). We'd like to dig into this kind of analysis further in the future, particularly to look at the return on investment of installing something like a masonry heater which has a significant cost up front but can lead to significant savings in energy costs over a long period of time.
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The work of the French masonry heater association, Association Française du Poêle Maçonné Artisanal (AFPMA), is extremely impressive. You can use your browser's translate function to investigate their website. They are working on open-source software for masonry heater design called FireCalc. It takes in inputs specifications on the air intake, firebox volume, heat exchange channel design, and chimney diameter and height and makes a calculated assessment if all of the parameters together are conducive to good draft. We look forward to reporting further on this development.
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We marvel at the development of masonry heaters in South America. The prevalence of slab-on-grade construction combined with latin can-do creativity is producing a impactful volume and quality of work. While we'd like to chronicle this in more detail in future communications, we point you to the work of Pablo Kulbaba and his website Hacono. We recommend subscribing to their newsletter. Here are some images from the most recent one:
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