BACKYARD BLISS | Simple and efficient systems for heating water and other stuff

Tim Barker (top left) with a rocket powered shower system part-way built. Pictures: Very Edible Gardens.
Tim Barker (top left) with a rocket powered shower system part-way built. Pictures: Very Edible Gardens.

Good Life Permaculture

Just to be clear, rocket stove systems do not involve rockets, nor is it rocket science.

What are they then?

The original rocket stove was designed to be an efficient cooking stove powered by a small fire fueled with twigs and tiny sticks rather than wood logs.

It's burned in a simple high-temperature combustion chamber containing a vertical chimney and a secondary air supply, which ensures almost complete combustion prior to the flames reaching the cooking surface. In summary it's super efficient, simple and low-tech, meaning almost anyone can build one anywhere in the world.

Due to their low-tech nature, they have been particularly valuable and appropriate for environments where people don't have easy access to electricity or abundant resources. Of special note, are some developing countries which have benefited from building small rocket stoves for cooking purposes, improving quality of life and use of resources.

As they're so easy to build, there are very few barriers (if any) for people making their own. As a cooking stove they have also been mass-produced at very low prices.

The principles were described by Dr Larry Winiarski from the Aprovecho Research Center in 1982 and since then stoves based on this design have won many awards, and others have gone on to develop other 'rocket powered' items including mass heaters and showers.

A rocket powered shower?

This works by directing the heat from a rocket stove to heat water. This can simply be a tank situated above the fire, or a water jacket system as used in conventional wood-fired water heaters.

A rocket stove shower system by the Very Edible Gardens team.

A rocket stove shower system by the Very Edible Gardens team.

For the direct heat systems, like the one pictured above, you require bricks to fashion the fire, a hot water tank (preferably recycled), flue materials, a tank stand and plumbing fixtures. On top of this you need a dose of enthusiasm and a large bucket of mud!

Warning: We know this is exciting, but there are a number of things to take care of.

Firstly be careful not to burn anything you don't want to burn. Secondly and most importantly, a hot water boiler contains considerable energy and if poorly designed can reach high pressures and even explode - that is why your home system has a pressure-release valve. Low-tech alternatives can prevent a high-pressure situation, familiarise yourself with how to do this safely if you wish to proceed.

In a rocket shower's most basic and super functional form, you don't need to spend a lot of time, energy and dollars on beautification to get easy, hot water, like the design pictured below by international rocket power expert Tim Barker.

Basic rocket shower designed by Tim Barker.

Basic rocket shower designed by Tim Barker.

The fire is lit in the cob structure below the corrugated iron cylinder. The heat from the fire is directed into this cylinder where it heats up the water.

The water in the tank is not used directly to shower with. Instead, cold water is piped through a copper coil in the water tank. The water heats up in the coil and plumbed to the shower stall.

Another example, from Milkwood Permaculture pictured bottom left, is slightly different to Tim's in that the hot water tank is vertical instead of horizontal. It is much more similar to a conventional "wet back" hot water system seen on many rural properties.

In this system the rocket stove is contained in the cob structure at ground level. The hot flue gas then heats a wet back (the steel box). The wet back circulates water to the storage tank on the right and from there can be used later.

Milkwood Permaculture's rocket stove design for heating water.

Milkwood Permaculture's rocket stove design for heating water.

Rocket power is for people looking to decrease their energy consumption and increase their connection to simple and sustainable methods of generating energy for their own needs.

  • Hannah Moloney and Anton Vikstrom are the founders of Good Life Permaculture, a permaculture landscape design and education enterprise based in Tasmania that creates resilient and regenerative lives and landscapes.