I don’t have photos yet, but will add them. (I have a scheduled event tonight, so photos must wait for tomorrow). Still, I can put up a general “layout” of the bricks and comments about the result of the “First Fire” event.
I’ve taken to calling this the G7O stove due to the general shape of the layers (though the 7 is more like the older kind that has a dangle hanging down from the top). I used a 16 x 16 inch cement ‘paver’ as a base just to make things insulated and flat. Then I built the stove base on that. Most likely, you don’t need both. The brick ‘base’ is that set of 6 bricks in the lower right of the image. That gives a heat retentive and fire resistant base and helps to prevent burning the dirt / grass under the stove while also giving a raised air intake to the firebox. Ashes or coals ‘sneaking out’ tend to land on the 16 inch ’tile’ rather than, say, dry grass.
The rest of the layers run from upper left to lower left in order. The first one is the ‘ash and coals pit’. It has the general shape of a G with the air intake to the right. That single brick set off by itself can be used as a ‘damper’ on the air feed (useful when running just charcoal for long slow burns). It can be laid flat on the short axis for no effect, turned ‘on edge’ for partial blocking, or stood ‘on end’ to fully block the air intake. (Well, not fully as the non-mortared joints leak, but enough to make it a slow coal burn with metered air).
The ‘hanging down” part of the G isn’t all the way down. The air channel is a bit less than one brick width. (This makes the outside edges non-aligned, but the structure better. So suppress that desire for smooth aligned external edges…) Slide it up just a bit to narrow the air channel about 1 cm. (An amount so small it doesn’t show up in this drawing). That lets the brick from the next layer up that cantilevers over that gap to instead ‘span’ it with a 1 or 2 cm ledge to sit on for that (otherwise) cantilevered end.
The next layer up is the 7 or hook shape (with dangling lead in part…) It makes the wood feed channel. The upper right brick spans the air feed hole below and rests mostly on the upper right brick of the G, but a little on that lower right brick once you slide it up a bit.
On top of the 7 layer, you can add one or two chimney squares. Just 4 bricks in a square (change the order of rotation for each layer so they are overlapping bricks in a ‘bond’). The lower left brick will cantilever over the wood feed hole, so slightly slide inward the bottom right brick of the 7 so that the (otherwise) cantilever brick rests on a cm or 2 of it. That way everything is very stable and strong (even if the outside looks a tiny bit ‘ragged’ or out of alignment).
I did two chimney squares.
I can also use a brick (or 1/2 brick) to close off the wood feed hole once you have a bed of charcoal in the fire pit. At that point you have a charcoal burner with draft controlled by the lower right hand draft brick.
Note that some of the bricks “poke out” from the usual all square shape. In particular the ‘dangly bits’ to the lower right of the G and the 7 shapes. By doing that, you don’t need to cut any bricks to make 1/2 bricks. If desired, you could just cut those bricks to length (and make that edge more smooth). In a locally produced version, you could even fire bricks of custom sizes so that the ‘cantilever’ was avoided while keeping a smooth outside wall. I was more interested in ‘fast strong and easy’ than in ‘polished and esthetic’ so willing to accept a slightly unaligned exterior. Laying the wood feed draft brick on the base can also act as a support shelf for longer sticks when not using it for draft control. That is, the ‘isolated brick’ (not shown) used to cover the wood feed hole for draft control in charcoal mode can be used to extend that support base under longer sticks when not used for draft control.
In comments on the USB charging wood stove article I described my ‘First Fire”. I’m just going to copy those comments here as they are appropriate. I’ll edit them a little bit for this posting:
Well, none of the local stores had the Coleman Oven, so I ordered it online. Delivery in a week or so. $38 tax and shipping included. It looks like they work OK as long as you add a bit of insulation via foil wrapping, even on a small wood camping stove. On a pile of hot bricks, likely even better. I’ll need to work out the stand for it and see how it goes. For baking, feeding a lot of sticks takes tending, so I’m likely to try ‘charcoal mode’ for a longer slower baking heat.
Also got the bricks. I’ve made the stove now and….. tum Ta DAH TUM!
We’ve had “First Fire”!
I’m tentatively calling it the “G70 Stove” based on the shapes of the key layers. many of the ‘pile of brick’ stoves that are called “Rocket Stoves” don’t have good adherence to the actual design features of the real Rocket Stove. In particular, they often do not have the wood feed shelf raised above the air feed channel. Instead, they often just feed air and wood into the same hole on or near the bottom. Just an L shaped tube, really. Mine has a lower air feed channel and a wood feed channel one layer higher, then the chimney. I also have controls for draft on both of those feed holes, so you can set it for ‘charcoal’ burn by blocking of the top wood feed hole and damping down the lower air feed. Rather like the StoveTec with two doors and dampers.
Main site here discusses their ‘two door’ stove:
If you read their description you can see why my ‘design goal’ included two feed holes and dampers.
StoveTec stoves are based on Dr. Larry Wininarski’s original rocket stove design and developed in collaboration with Aprovecho Research Center. The insulated combustion chamber utilizes low-density clay and is unique to StoveTec stoves.The result is a highly efficient stove that is preheating the gases, and burning a large percentage of the smoke and gases as fuel, reducing emissions and reducing fuel use.The insulated combustion chamber also protects the user, since the stove body will not burn the user if contacted while cooking
The 2 door store is designed to burn wood, flammable biomass, and/or charcoal. Please note that Charcoal manufacturing robs 70% to 80% of the energy of wood during the production process, and releases large amounts of Methane, CO, CO2, and other toxic gases into the environment.These toxic gases are introduced again while cooking.The intention is to provide you with information regarding the consequences of stove choice and the fuels you select for cooking.
The 2 door stove does have an advantage simmering or during low firepower grilling, in regard to ease of low temperature control with the lower ventilation door.Wood or biomass embers do not require constant monitoring with the 2 door stove after the combustion chamber door with the attached fire brick is closed.
The attached firebrick on the top combustion chamber door is only protecting the paint on the combustion chamber door and may vary from stove to stove in shape and appearance.This door is closed using charcoal fuel, or during simmering operations with wood or flammable biomass fuel.
So I use a brick as the ‘door’ for my wood feed port. Coupled with the ‘damper’ on the lower air port, I ought to be able to have full control for simmer, grilling, charcoal baking, etc. Much like in these stoves.
But not at a cost of $125 from Amazon… While I’d love to have one of these for ‘at the beach’ or ‘car camping’ where it is much more portable, in reality I’d likely use something even more portable then. For stationary use in the Third World (their design point) it’s great as it is self contained and can be moved outdoors for cooking, then brought inside when done. But I wanted to know “was there a cheaper way?” Preferably one that could be done after a Great Quake knocks out everything in the area and takes no, or nearly no, tools. (I.e. not a lot of brick cutting and dressing or mortaring and I don’t need to go digging for my brick cutting chisel in the possibly flaming rubble of my garage in the dark…).
Mine is a bit overbuilt on materials. I could make one almost as workable for about 2/3 the bricks. Still, I like the deluxe features. And I can always use the bricks for something else later if I get bored with it. ;-)
So how much cost? I bought 24 bricks, but 25 is better ( I’m using an existing brick for one of the dampers and as the fuel shelf). You can get these for about 24 cents as ‘cement’ bricks, but fired clay is likely to be more durable. They run at 52 cents here. So $12.48 was spent, but $13 if you get the added one. I also bought a 16 inch square ‘base’ paver of cement for $3.50 or so that wasn’t really needed. As I’m using a layer of brick for the ‘floor’ of the fire area. You could likely leave out either the ‘base’ paver slab or the 6 bricks used as a base that is mostly just a fire proof layer between the cement ‘base’ and the rest of the stove. So do I really need two ‘base’ layers?… At any rate, all up, I’m into it about $16 for my stove. With completely reusable materials.
“First Fire” was on ‘found materials’ that consisted of standing dried stems from Jerusalem Artichokes that had died back for the winter and some hulls from lima beans ( I’d harvested the seeds and left the husks where the stove got built…) Lit on the first try, burned cleanly and nicely, and consumed things pretty much to ash. No smoke in operation and very little at start up. (At the very end; the nubs of the last stems didn’t burn fully, but I didn’t have much coals by then and those were the damp ends from near the ground…) All in all, quite pleased. It would likely smell better with hardwood or fruit wood, and I’m going to try it as a Hibachi / BBQ of sorts “sometime” toward Spring.
As an ‘ersatz stove’ it is fast and easy to make and very cheap to buy the materials. It works on any dried plant materials (as evidenced in the ‘First Fire’…) and does well. You have great heat control with either fuel feed rate or dampers (or both). It was modestly windy today and the wind was right into the fuel feed. No problem other than a bit of ash out the top on gusts. (A rebuild will likely point the fuel feed away from the primary wind direction and / or I’ll add a wind screen AKA cinder block ;-) up wind. ) “Start time” was about a minute (less if you don’t mind cooking as the fire gets rolling) and “turn off” is about the same, at least with the ‘trash sticks’. Using larger lumber like wood likely to take longer. I can see having some of each and choosing size based on expected burn time. One could always ‘turn off the stove’ very rapidly by dunking the stick ends into a water bowl then spraying the coals with a water bottle. Biggest risk would be heat shock breaking a brick. 50 cents… Personally, I’d just set the tea kettle on top of the stack to start warming some water as the fire runs down, or put some muffins in the oven to warm…
I didn’t put a grate on the top yet, but one from the portable BBQ ought to be fine. I’m also pondering 3 or 4 small bricks / stones as a pot support. We’ll see what I end up with. Three or four ’1/2 bricks’ spaced around the top of the ‘chimney’ would be fine. Any of the examples used on existing “16 or 24 brick rocket stoves” will work here too. Stability is quite high (as you might expect from a pile of 2 dozen bricks…) and mortar is not needed.
So I’m a very happy camper, even if “camping” in the backyard.
For anyone not familiar with them, a picture and a couple of pointers to the basic Rocket Stove tech:
Here you can see that my ‘contribution’ is mostly just turning the air intake 90 degrees from the wood shelf so that there is no need for a metal support (that can be made from an old tin can, but few people do and it make the fuel port a bit cramped anyway). That 90 degree change lets the structure be easily made with a brick stack. Then adding two “loose” bricks to use for dampers on those two ports let you choose high power wood feed with added air, lower power – even ‘simmer’, or “charcoal slow mode” with the wood fuel port closed and the bottom air damper partly closed for longer, slower, simmers and roasts with less wood tending time.
Of course, there is a wiki:
The Rocketstove.org folks:
These folks have several videos and pictures of other kinds of Rocket Stove:
Frankly, while the ‘stove in a bucket’ designs are likely a bit nicer for day to day use, the ability to build one in less than a couple of minutes from a pile of bricks “post quake” is more interesting to me. That it seems to work about as well (judging from flame size / heat out the top) is just icing on top ;-)
Or maybe it’s just all those ‘muscle memories’ of cuts from working sheet metal and thinking that ‘in an emergency’ working with tin snips and rough edges is not high on my ‘want’ list…
These folks have one of each. This link is to there mortared in place brick one:
but has a link to their 5 gallon can one as well.
This video goes through the details and technicals of making a Rocket Stove, including how to make lightweight more insulative bricks from scratch (though you would need to have or make a 1000 C kiln). Still, it is good to know what the specific technical targets are for an ideal stove when working out how to make one for emergencies and minimal cost / materials circumstances. Clearly, though, this is not something you will be doing at 11 pm in the dark after the quake…
That ought to be enough to provide some ‘context’ on Rocket Stove state of the art.