Cookstove + Masonry Heater Hybrid

Originally published at: Cookstove + Masonry Heater Hybrid - Firespeaking

The impetus of this project is to create a single unit that combines a functional cookstove with immediate heat production with an efficient firebox for prolonged masonry heat storage. We will draw from medium-sized “batch-box” development and use bypass dampers as switches to significantly alter the flow through the heater depending on the output desired. An important part of the project will be to experiment with an open-source flow for project development. This project is being developed in the context of a hands-on workshop that will be realized at the Masonry Heater Association’s 2022 Annual Meeting.


I like this idea, kind of the best of both worlds. Can we add an oven too? Half joking, probably adds too much complexity. I am planning out a small, approx 500 ft^2 home (300 footprint + loft) and would love to have something like this in it. Eagerly awaiting more discussion. And willing to be a guinea pig if one is needed. Home size might be borderline too small to need that kind of heat, but it’s a cold climate so maybe it’s worthwhile…

@FerryCounty, I am just in the process of working on the design, and have tentatively added an oven and am planning on hot water heating too. Stay tuned, I will try to share some screen shots shortly. Indeed, I am hoping to get rolling on this project.

Before preparing more technical sections, I wanted to share the process of conceptual design… exploring different variations, mainly with a broad conceptual view in mind but trying to keep the technical inner workings as I evaluate each stove option. Here are some different variations on this idea. I think I would like to settle on the one at the end and will begin to draw out the inner workings. Interested in people’s feedback…

Just about the simplest cooktop and mass combination… possibly not enough room for the channels we would need…

Full-blown, large wood-fired oven…

Kind of classic but requires a custom cooktop…

This is the one that I would like to detail:

Here is a little more detailing on the concept sketch, also showing my hope that we can include a hot water heat exchanger that thermosiphons to a hot water tank.

Here’s the SketchUp file if anyone wants to play around with it or insert it into a home design:

Cookstove and Masonry Heater Hybrid (SU v2021).skp (1.7 MB)
Cookstove and Masonry Heater Hybrid (SU v2017).skp (3.6 MB)

The next step is to start drawing more technical sections showing the flue paths.

Anyone have any votes about how best to name this project!?

  • Cookstove & Masonry Heater Hybrid
  • The “Power Station” Heater
  • The “Mother Ship” Heater

0 voters

Suggest other names and I’ll add them to the poll.

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.

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@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.

I look forward to this. I will have to look at getting a link up on my website for this forum so that others can see it, learn and contribute.

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A post was split to a new topic: Joseph Crawleys Multifunctional Heater

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!

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Hey, hey! Welcome Jim! Another great heater builder joins our ranks!

Indeed, once you get interested in masonry heaters, especially from first-hand experience, that interest tends to continue strong.

I love the “Heat n Eat (alator)”! Just now realizing I can’t change the poll after it has been live 5 minutes.

Yes, looking forward to further developing the design. Stay tuned!

A post was split to a new topic: Masonry Heaters for Small Spaces

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…

And here is a first sketch of the main heat exchange battery. The oven and hot water coils still need to be detailed in this section…

Stay tuned for progress next week!

How’s the design coming along?

Hi all. Here’s an update of what I’ve been working on…

The first is just a section summary graphic so that the sections can be understood in the context of the overall project:

I developed a first go at the flow pattern at the level of the bench, which also includes the ash collection area.

I was surprised at how complicated the entrance into and out of the bench ended up being and am hoping I can simplify it. It is a constant goal of mine to keep things as simple as they can be.

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?

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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.

Looks awesome brother! Interesting fireboxes. Are you considering a port or is the firebox exit full riser size?

Thank you for the feedback.
How would the Austrian heater calculation program account for an even smaller fierbox like the one linked below easily powering a bench with a lineal run of 18’ (6 m)?

I am thinking the Annual Meeting is a good place to test things out and when it’s been cold, the heated bench has been appreciated.

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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.