Shop Cabin Stove Process Photos

These photos document the build process of the Shop Cabin Stove.  This is a project in continuous development. The best way to receive updates is to join our mailing list. This documentation is provided on an open-source basis.

You can derive a lot from knowing that the bricks lay out to a modular 4″ x 8″ x 2 3/4″ layout, the fire brick are 4 1/2″ x 9″ x 2 1/4″, and the firebrick splits are 4 1/2″ x 9″ x 1 1/4″.  I recommend Northstone Heat Supply for hardware.  The next iteration of the Cabin Stove will be designed around readily available hardware.  As stated, the very best way to stay involved with this project is to join our mailing list.


Cabin Stove Contact Form

Please initiate all email correspondence regarding the Cabin Stove via this form. You can also reach us at (541) 688-0948 during normal business hours (Pacific Standard Time).

 

 

The Cabin Stove at Rob and Mal’s

The Cabin Stove at Rob and Mals

This heater was built as part of the Sustainable Shelter Workshop Series at Aprovecho. It completely turned around the residents’ experience of their home in winter time. Their previous propane heater provided a “wet” heat that also didn’t reach the outlying bedrooms causing mold issues. The design is a Cabin Stove with heated bench. The design borrows from both the tradition of masonry cookstoves as well as the modern phenomenon of rocket mass heaters with heated cob benches.

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Links:

The Harlan Cabin Stove

The Cabin Stove @ Harlan

The Harlan Cabin Stove was built during a two-day workshop in December 2015. While I am very happy with it architecturally, itis an iteration of the design that shows it still needs some fine tuning.

I suspect that we need to tighten the gap beneath the metal of the cooktop in order to get more heat to rub off on the cooktop and provide immediate heat. Also, it is likely that reducing the thickness of the cook plate from the current 3/8″ to 5/16″ or 1/4″ will provide more response.

This iteration demonstrates that the so-called “Sidewinder” combustion box still needs tweaking. There is a lot of mass around the fire before it hits the cooktop. Using insulative refractory materials out of the wear zone is one possible improvement. Burning wood in our current wood stove at home as well as a recent repair on a state of the art German kacheloven firebox is solidifying my understanding of the differences between an underfire “oxidizing” air source and side and over-fire air which is good once gasification has been reached. Our next iteration will be in our own shop and I will try to combine both elements. Stay tuned.

The complete masonry plans for this stove are currently offered for sale as The Cabin Stove Plan Set. As this is an open-source development project, the price of the plans actually serves as a pledge of support in helping us to continue to develop this “cookstove” / “masonry heater” hybrid. You can think of a purchase as helping to buy bricks, coffee and welding wire for the next iteration we will build and to have time to document step-by-step photos. Go for it!

Links:

Cabin Stove Workshop – Dec. 5-6 – Harlan, OR

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HOW TO BUILD A COMPACT, WOOD-FIRED MASONRY HEATER

Learn to build a compact wood-fired masonry heater designed to maximize heat gain from minimal amounts of fuel. In this intensive two-day workshop, we will show you, brick by brick, how we build a small, efficient stove that combines space heating with cooking capabilities. We will also cover basic theory of combustion and retained heat, stove designs, hardware, permitting, theoretical and some hands-on masonry (including sourcing and mixing mortar and other materials, cutting brick w/out a saw, keeping things plumb and level, basic brick-laying, etc.)

The masons leading the workshop are Max Edleson, a professional heater mason (see his portfolio here), and Kiko Denzer, a DIY mason, teacher, artist, and author (handprintpress.com/kiko). The heater will be installed in a small cob cottage on a family ranch.

Like much larger (and more expensive) masonry heaters, the Cabin Stove burns so clean you won’t see any smoke coming out of the chimney (except at startup). As it burns, heat travels through yards of masonry channels, heating up many hundreds of pounds of brick. All that brick works like a battery — once charged, it will keep you warm and comfortable for many hours. In the cold season, one or two small fires per day is all you need to heat a small building (the design can be adapted to heat up to about 1,000 square feet of an open plan building). More information about the “Cabin Stove” is available here….

The workshop takes place on December 5th and 6th, in a beautiful valley on a salmon creek, about 45 minutes west of Corvallis, OR, with primitive facilities. Enrollment for this two-day course is limited to 5 people at $150 each, pre-paid; if you’re serious about building your own stove please get in touch. Some scholarship funding may be available.

The Cabin Stove – A Small Masonry Heater at Aprovecho Research Center

Important note: I have preserved this post as-is for archival purposes. On-going development of the Cabin Stove is documented at The Cabin Stove Page.

A good part of the month of August has been dedicated to the research, development and construction of a small multi-functional masonry heater I have been calling “The Cabin Stove”. Eva and I have both been working as instructors in the first year of the Sustainable Shelter Workshop Series at Aprovecho Research Center in Cottage Grove, OR. The building that is the focal point for this course has been designed to be just slightly smaller than the legal requirements for permitting so that it can at the same time be a teaching tool as well as a laboratory for a basic building system that a group of associated natural builders in the Pacific Northwest considers to be a sound and ecological way of making a home.

The challenge of the design of the Cabin Stove was to come up with something that was very compact but also still resembled and functioned like a masonry heater. The design criteria included heating the small space, an efficient and clean fire, utility for cooking, heating water, combining some quick/immediate-releaseheat with slower retained radiated heat, relative ease of construction, not too expensive, aesthetically pleasing, and being as compact in size as possible. A very interesting process to try to combine all of these together.

Our test firings of the prototype in our shop were very promising. The fire burned well and had no problem making its way through the longer pathway, even notably when the door was open with the beautiful cast fire screen reducing the overall air intake to a moderate amount. I think the design meets most of the criteria listed above well with the exception possibly of cooking utility since this was compromised to accommodate other features.

For the initiated, it is basically a very compact J-loop contraflow with a bi-pass that runs directly to the flu and allows it to function even as an open fireplace. Rather than insulating the top of the heater as is done often in masonry heater construction, there is a 1/4″ steel plate placed on top that serves as a cooktop and source of immediate heat. I am optimistic that the proportion of immediate and retained heat will be a good one for our bio-region where temperatures can fluctuate greatly during the day and from one day to the next. We are within but on the outer limits of the kind of climate that masonry heaters were designed for which explains the need for continued development and innovation.

I did notice in firing the prototype that the big steel plate I had placed on it arced noticeably when hot so I welded a 3/16″ frame onto the Cabin Stove we built at Aprovecho though I am quite sure that the heat will play its funny games and have its own way with the final shape of the steel plate. Cast iron is almost certainly the way to go for the top although I do not know of a source of affordable custom sizes.

Although the heater at Aprovecho was designed to be a double-skinned heater with a compressed earth block and local stone veneer, I am very excited that we will first test the heater with a single skin. A neighbor has offered to lend his carbon-monoxide and air-quality monitors to test whether there are any dangers that result from expansion cracks in the single skin. Given our climate in Oregon, the prospect of building responsive single skin heaters is a very interesting one. (Note: the variation in the firebrick is because we used firebrick out of an old heater that had been taken down. The students re-milled each brick to cut away the old mortar to return the brick close to original dimensions).

I have recently been very inspired by the Open Source design philosophy so I share the rest of these photos of process in that spirit! Stay tuned for more on this heater and other research and endeavors. Click to see any images enlarged.

You can see some other details of the building, including one of the timber frame’s posts; the faswall and stone stemwall; and strawclay insulation packed in between Larsen-truss style framing.


Custom-made heater hardware, made in our shop from scratch.

Details of Hot Water Serpentine. More on Plumbing for Thermosiphoned Hot Water Systems….

Make sure to read this more recent post on the Cabin Stove 2.0!

The light and surrounding forest were really exquisite when I took these shots of the veneer material. The compressed earth blocks were made by the students.

Find out more…..

Response about Rocket Stoves in MHAmember Forum

This spontaneous essay is a response to this great piece by Alex Chernov, as presented in the MHA News.

From: Max Edleson max (at) firespeaking.com
To: MHAmembers@yahoogroups.com

Date: Sat, 3 Dec 2011 07:52:43 -0800
Subject: Re: [MHAmembers] member news

Indeed, Alex, the article you have written is great and this area of research you are pointing to is very exciting.

The issues you bring up are excellent. I would like to try to add to what you have written.

As far as advantages of the rocket stove, the idea for those inclined to do things themselves to be able to build their own heating system without too much expense and without too many necessary tools is one that is very exciting – one that ignites a passion. The relative simplicity of the rocket stove design with few specific and basic parameters, allows for a great deal of customization and flexibility in design which is also very exciting and often practical when placing a heater into a space and further fuels the doers interest and passion in building it.

The particular combination of immediate heat at a usable rate and stored heat at an impressive rate of accumulation is also an area that the normal rocket mass heater design really shines in.

The bench is a wonderful aspect of the design. Both from a comfort standpoint of being able to sit your butt and back on soft, penetrating heat and also from a social perspective. I think most of us who have experienced the benches from the last couple of years at Wild Acres have experienced this.

Novelty also always has its appeal, at least to a certain sector of society!

But then there are many significant disadvantages, most of which you have pointed out. The subfloor: the rocket mass heater, as developed by Ianto Evans, evolved from experimentation in cob buildings where the heaters are built on grade (on some combination of compacted earth, gravel, and sometimes an adobe-like subfloor). Similar to the conditions of a concrete slab on grade that is found in many garages, for example. So you have a nice, solid, load-bearing floor that is also non-combustible that you can spread your design out on. This is essentially the opposite of how most homes are built in north america: light, lofted, insulated and combustible floors. This point, as you point out, ends up being pretty essential to design considerations as an on-grade subfloor generally would suggest the possibility of letting a heater’s design spread out while a joisted wooden floor with a foundation coming through the middle of it tends to suggest a more compact layout to minimize the size of the foundation and related expenses (especially in a retrofit).

Also, as you say, the user experience of a rocket stove can be summarized as finicky, at best. I have seen several rocket stoves that have been the core of people’s homes and worked very well day in and day out. I have seen others that worked ok and I have seen a surprising amount that don’t work so well or at all. The flexibility of design, the do-it-yourself style and, significantly, the fact that many I have seen were built in very-rushed workshops leads to an unpredictability that is often difficult to diagnose once things are sealed up if they don’t work. This can be very challenging.

Also, general rocket mass heater design so far has under-emphasized the importance of cleanouts, particularly in bench designs with bends in them. It is a process to remove the barrel and re-seal it, if and when this is necessary. And a plastered cob bench can require significant maintenance, at least bi-annual.

So, all these things have left me also in search of incorporating the advantages experienced from rocket mass heaters with all of the experience and advantages that comes from masonry heater building.

One note on hardware and expenses. I have come to realize that the door is the significant technnology that fundamentally distinguishes open fireplaces from masonry heaters. eg., that reduces the amount of air entering the combustion chamber so that it can not only be efficient but also be throttled in such a way that the combustion and long tail of combustion can be guided through the much longer channels of a masonry heater. This is probably both obvious and often overlooked. The door, especially metal doors, are a relatively new technology in the long history of fireplace building man(and woman)-kind. Perhaps one of the most significant contributions of the rocket stove is to accomplish this reduction of air into the combustion chamber without a door. It does this so successfully that you can even burn the fire upside down as we have experienced. The ideal amount of air is that which generally fits between the split burning wood. A brick is often used to close off excessive air if the firebox is not completely full of wood. This last element, for example, is critical and an example of the very important fine-tuning that is happening in a rocket mass heater burn.

At the same time, this is a very important design limitation since it prohibits sizing up the firebox without important repercussions. Those who were observing may have noticed us “barefoot builders” during wildacres 2009 really experimenting with this aspect. When we re-built the rocket mass heater inside that was eventually plastered with the lime we had made and painted with a naked lady (yes, that one!) we had built the front in such a way that we could make different fireboxes. If you remember, we tried putting a small glass door on the front of the down-draft firebox but found that even this slight modfication in widening the firebox to accomodate the glass door meant that the wood did not stay as organized as it needed to and, I think, allowed more air in than was necessary, especially when the firebox was not completely packed with wood.

As I have begun to experiment with making doors, I have come to appreciate doors a lot more and the care and cost involved in either casting or fabricating them. I have also come to think that in temperate to cold climates, firebox doors should really be thought of as a family heirloom and at the center of a family’s wealth – after all, there are times in history when money isn’t worth much more than paper for starting a fire which people in different parts of the world have experienced in inflationary situations like I experienced in Argentina and that I’m sure people in Russia have experienced. I don’t think that people consider the expense of either a vehicle, a computer (pillars of modern life) nor for kitchen appliances in a remodel in the same way they do masonry heater/cookstove hardware and the other related expenses. This may just have been my previous bias coming through to though I think it reflects the current moment and society’s related values.

One more thought before I get out into the cold to organize rock from a mountainside into some semblance of a beautiful heater skin. The issue of code. As I have begun to work building heaters in more code-respecting(/code-enslaved) situations, I have had opportunity to reflect on both its advantages and disadvantages. The only, main and significant advantage of code that I understand is that it ensures safety and formalizes that responsibility between the builder and the people living in the home, especially where this relationship is mostly otherwise anonymous. It also ensures a standard of quality to some degree by ensuring that things are done in a certain way and that certain materials are used.

On the flip side, I have come to understand that the whole issue of building codes and inspections has a lot to do with counties and other jurisdictions ensuring that what you build in your home not only serves you, but really more importantly, someone who you either might like to sell your house to or someone who would like to buy your house (hopefully under favorable conditions). While I can see the benefits of this, I get that uncomfortable feeling that in this situation, as with property taxes, it is really the county that owns your house and what you do with it… and I don’t think this is so conducive to really connecting with one’s home and where one lives.

There is also that element of stilting forward evolution.

These comments, especially the last ones, should be taken with a grain of salt. Most of this is to say, yes!, very exciting what you have written and propose Alex!

Max

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