Max, I have always found the 9"wide or so firebox of most cookstoves to be limited on how many channels you can add on to them. So we normally will use one of our standard 13"w x 18"d fireboxes and add a cookstove top above the firebox and then vent the exhaust out the side of the firebox into a down draft channel and a large bell or just into a large bell. Kinda like the MHA workshop we did 2 or 3 years ago. Below are 2 photos of a simple bell on the side and a more complex bell.
@SolidRock, it’s an honor to welcome you to the forums. For those who don’t know Eric, he is one of North America’s most accomplished masonry heater builders.
Indeed, I am planning on a slightly larger than normal, for a cookstove, firebox and importantly for the main combustion route to lead into a significant heat riser which I am hoping will produce the kind of thrust that we see in rocket mass heaters. I should have some sections done within a week so that the inner workings will be more understandable and open to critique and response.
The Heat n Eat (alator)! But in all seriousness, i’m really looking forward to seeing your design come to life in April. It reminds me of the first masonry heater I ever saw, at Granja Valle Pintado back in 2011 with a small water tank up above for hot water heating and a lounge-y heated bench… I became infatuated with the idea of hot cob!
Hi all! I wanted to post some drawings before the week was out. Here are two sections that I have begun to develop for the inner workings of the stove. It still needs a good bit of refinement and a couple more sections to fully describe its function.
This is my first shot at describing the combustion chamber and the two possible pathways that gases can travel as they exit. It still needs some effort to make it “cozy” for the fire…
I started thinking that the firebox design on the right, with the inclined exit, would result in better organization of the fuel, fire, and its byproducts. The down side is that it complicates the construction some.
I would love to receive feedback on any of these ideas/drawings. It really provides energy to the project to know that people are interested and there is a dialog happening. What do you think of how this is developing @Canyon, @mheat, @Tallgrass, @SolidRock?
Max, the bench is looking quite long for the size of the firebox. I doubt it would balance out in the Austrian heater calculation program. I would suggest cutting the bench length in half, mainly due to the size of the small firebox.
The angled firebox back is not needed.
Looking good Max! Where is combustion air being fed? Through the door? The classic-ish design of the rocket stove horizontal “burn tunnel” and 90 degree entrance to the riser was the original point of mixing to induce the most turbulence and combustion. I wonder if the 45 degree angled exit into the riser smooths out the transition and it if wouldn’t be worth annunciating the initial throat to more of a point like Peterbergs tripwire brick to really enhance mixing in the 45 degree angled run.
Also, on a selfish note, whats the software you are using for these structural design prints, looks very clean and welcoming way of presenting a design to a building department.
I have just always been so intrigued with the efficiency of the cigarette-style end-burn we have witnessed in an original rocket mass heater. This is an effort to allow for more fuel at a time with a glass door for viewing but maintain some of the synergy and symmetry offered by the original design….
This is a good point. One of my personal goals for this project was to take the time to review what had been developed and documented in the other forums with regards to batch box development. Your response forced me to begin that review process of the “p-channel” and the “tripwire”. I will see if I can continue design development to document that area that you and @Canyon are talking about.
Nothing selfish about asking a question in a public forum! You might be surprised to know that I am doing the design drawings in SketchUp. It is known for its 3D modeling features but I have found myself using it to draft in a more traditional way. I find sometimes when I am 3D modeling that I get lost in the specifics of each unit in a brick-by-brick approach instead of being able to design more globally. I use the companion program LayOut which is part of the Pro suite to add our logo plate, labels, dimensions, etc.
This is exciting. While I can’t speak to any of the technical specs, I think the concept and the aesthetics are coming along nicely. I like the added bench. The one masonry heater I have seen in operation had an air intake, I believe, right inside and below the door, so that it kept the firebox door from getting dirty. I don’t know how much that adds to the design complexity
I am going to update the original post with the full drawing set, where we are at now. I think that the original concept has mostly been flushed out at this point but there are still many details to continue working on.
One example is the switch from firebrick shiners to splits to accommodate the flow around the oven. I had imagined this from the start but seeing it drawn leaves me feeling that the portion of the wall where the bypass damper is mounted appears weak.
I also know that I need to draw a section from the front exploring the second route of the combustion gases across the cooktop.
This is a creative process and it is full of the excitement as well as the uncertainty of any such endeavor.
Here is a summary of the hardware that Firespeaking supplies that you would need to build your own version of this project:
The cookstove formation seems like the weakest part of the whole design. @Canyon , you had asked about the “port”… I’ve sketched it on the right. It’s currently roughly 6 w x 6 3/4 h. Thoughts on recommended size?
One of the biggest dilemmas I’m meditating on is that their is a confluence between the longer flow through the vertical masonry heat exchanger and the cookstove flow as they join towards the bench that I feel could be problematic in that it might cause a short circuit of the longer path and disrupt or weaken the more “rocket” type combustion we are trying to create when not in cooktop mode… Any thoughts out there? I will be thinking about it.
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