Rocket Stove DIY

We use our rocket stove every day throughout the warmer months, cooking breakfast, coffee, dinners, lots of large preserves and pasteurisations and whatever else we would otherwise use a hotplate for. We do all of this cooking with sticks as the fuel, seriously - just a handful of sticks cooks our breakfast, or an armload of sticks for a preserve. This design is for outdoor (undercover) use and is made using readily available waste materials.

Our rocket stove in action - cooking eggs for breakfast

How it works.

Wikipedia says: ‘a rocket stove is an efficient and hot burning stove using small-diameter wood fuel. Fuel is burned in a simple combustion chamber containing an insulated vertical chimney, which ensures almost complete combustion prior to the flames reaching the cooking surface. Rocket stove designs are most often used for portable stoves for cooking but the design is also used for large fixed stoves in institutions, and to make rocket mass heaters for heating.

In field tests in India, rocket stoves used 18 to 35 percent less fuel compared to the traditional stoves and reduced fuel used 39-47 percent compared to the simple traditional open three-stone fire, as well as a large reduction in emissions.’

Patio heater - found at the tip shop for $10

We make this basic rocket stove for outdoor home cooking by re-purposing one of the least efficient heating designs around - which also makes it abundantly available as a resource- the ‘mushroom’ or ‘umbrella’ gas patio heater. Wikipedia says ‘one patio heater can produce four tons of carbon dioxide annually.’ I’ve heard they can use a bottle of gas a night! 

To do the same you will need a patio heater shell or similar vessel- our favourite is the ‘Fiammetta’ Stainless Steel one people get from Bunnings before they realise how much gas it uses. You could use anything as a body but stainless steel lasts a lot longer when exposed to high temperatures. These ones also have two 125mm holes which fit a 5 inch flue pipe nicely. 

You will need:

- 1 x Standard 900mm length of 125mm (5”)flue

- Something to block one end of the flue (1kg milo tin etc),

- Trivet of some sort (bbq wok ring etc)  

- 50 litres of ash or other heat proof insulation 

You will also need some basic tools:

- A pair of tin snips or angle grinder for cutting,

- A spanner and screwdriver to dismantle the patio heater

Step 1: Dismantle the heater. Take out the central pole, remove the base, wheels etc.

Step 2: Stomp on the top of the heater shell so it will sit flat upside down. You could also use a mallet or whatever works for you. Turn it upside down.

Step 3: Block the central hole, where the central pole came out (no heat here so anything can be used as long as it will stop ash leaking out).

Step 4: Block the 4 holes around the rim or cut off this section to match height of vertical flue (next step..) We find it best to cut this bit off.

Step 5: Cut the flue pipe in half allowing you to create a T-shape, the horizontal half has a hole cut midway with tabs to support the other vertically.

Horizontal flue with hole cut and tabs ready to receive the vertical flue

Step 6: Block one end of the horizontal and fill this end with ash to make an L-shaped combustion chamber. We have found that for this design, it is best to make a T-shape with the flue, it supports itself and fills both patio heater holes, it also allows space for a bit more ash to build up before needing emptying. 

Step 7: Fill the shell with ash or other heat proof insulating material. We sift out any charcoal to make sure it won’t catch fire. 

Step 8: Place the patio heater base on top to cover the ash. The base makes a nice wind shield so the heat isn’t blown out from under your pot. 

Step 9: Place a trivet over the hole in wind shield to raise pot between 1 and 5cm high seems to work ok. You can also use a solid (raised) hot plate to stop your pots getting sooty but it reduces efficiency a bit.

Step 10: Innovate - 45cm round ‘jumbuck’ gas bbq plates fit nicely on top, turning it into a BBQ.

- A clothes dryer drum sitting over the top can create an oven (good for baking in a camp oven etc)

- A 1/2m length of 1/2 inch copper can help get the stove going quickly without risk of burning your eyebrows etc. 

Enjoy using your newly built rocket stove! Let us know how you go, and any new findings and innovations you make :) We've found that cast iron pots and pans are the best ones to use with this design.