Brick Rocket Stove exploration

Getting Firebricks

I decided to go with bricks as a material for the rocket stove because it would be simple to assemble and disassemble the stove and play around with different configurations. The 22x11x4 cm firebricks Obramat sells turned out to work perfectly for what I had in mind; the 2:1 size ratio allowed me to easily create stove configurations with the bricks fitting snugly. I also bought a sack of fire-resistant oven mortar while I was there.

Assembling a Base

For a base, I got six larger firebricks with holes inside. I placed them on a thin layer of dirt for a bit more heat insulation, then filled the holes with oven mortar to create a solid base for the stove.

Stove Configurations

After that, I started assembling different stove configurations.

A rocket stove works by creating a strong airflow: the fire inside the base burns fuel, drawing in fresh air through the opening. As the hot air rises through the chimney, is creates a draft that pulls in even more air. The taller and narrower the chimney, the stronger the draft and the hotter the burn at the top.

To function properly, a rocket stove only needs a few key elements:Inside the base, there must be a hole for placing the firewood. I added an elevated grate between the first two layers of bricks to lift the wood and allow air to flow in freely underneath.

On top of the base sits the chimney, which channels the heated airflow. At the top, it gets very hot very quickly—hot enough to cook or have a barbecue.

#1

The first iteration with a tall chimney burned clean and hot.

#2

Since the goal was to bake pizza on the stove, for the second configuration I aimed for a wider chimney to get a larger area in order to heat the pizza evenly.

Testing

From the first tests I learned that I should add some aluminum foil to protect the food from flying ash particles.

Improvements for the next iteration

Experimenting, I quickly noticed I would need more bricks to construct the pizza-baking rocket stove I imagined. Using 55 bricks—the maximum amount I thought to be useful for this project—I tried to make a stove configuration that fulfills two requirements: a diameter of 30 cm to be able to bake a pizza evenly, a roof to keep heat inside, and a chimney as tall as possible.

To stack the bricks in a way that gains a lot of height using little material greatly compromises structural integrity. I was planning to use the oven mortar I used for the base also to stick the bricks together. However, since the oven mortar dries slowly and is not very sticky, it will probably not enable me to build the oven in a few hours.

To deal with this issue, I will experiment with two approaches. One is to use clay instead of oven mortar, since it is also highly heat-resistant and way more sticky.The other would be to drill a number of holes into each brick and provide iron rods that would fit into these holes, essentially creating a slot-together stove construction system—or even combine both methods.

To build the roof on top, I'm planning to either use a chisel to create notches on the sides of the bricks at the top of the wall, where more iron rods could rest to serve as scaffolding to place stone bricks on top. Alternatively, the metal rods could just be fixed with clay.

Lastly, I will have to start collecting wood scraps from the workshop and store them inside to accumulate dry firewood.

CCL v1.0 — AI contributed as Drafting Assistant in Research. All other phases were fully human-led.

AI R1 – v1.0