Rocket Stove Water Heater
It looks like a white camel with a fat hump on a pillar but in actual fact its a hot water system. Rocket Stove technology has been around for many years, dating back to ancient China as a method of central heating, but this rendered mud brick construction is used out in the field near the student camping area at Zaytuna farm.
This Rocket Stove also has a wood drying cabinet below
We’re outdoors filming the last sequences for The Urban Permaculture DVD at the Permaculture Research Institute in Australia and managing director Geoff Lawton points out his new toy.
Washing his hands in the outdoor sink he demonstrates how well it works. Upright timber that looks like thin fence palings or tomato stakes are standing upright and a warm fiery glow. A great idea I think. Only the last few inches are burnt and the stick burns down like a candle, falling down under its own weight.
In the cold winter air, its comforting to stand next to this quiet system as it burns very little fuel. The strange hump contains a 44 gallon drum that is the engine of the water heater system. We’re impressed. Geoff always has something interesting to show us.
Geoff explains the benefits of using a rocket stove to heat your hot water. Very little timber is used he says, in fact only one fifth the timber is needed to harness the energy used in traditional stove hot water systems.
The rocket stove is an ingenious system that radiates hot air around the thermal mass of a water filled drum. Inside the water filled drum is about 18 metres of tightly coiled copper pipe that will turn cold water into hot. Its the water in the coiled pipe that will be used in the house. The water in the drum transfers its thermal mass energy to the coiled tubing. Low tech solutions like this are terrific to see. There is very little smoke out of the flue. We think of our own increasing power bills as Geoff points out the timber drying and storage cabinet built into it.
By now we’re getting hungry. I mention to Geoff that I have an improvement on his design. Could he also turn this into a pizza oven as well? Now that would be an even better idea – suited to good permaculture design. One system but with many alternative functions. The essence of good design 
There are many different rocket stove designs. For some reason they appeal to Permaculture people who always hanker for good innovative design that is also energy efficient.
You can visit Milkwood Permaculture for even more innovative uses including a hot water shower system.
Rocket Stove technology like this could also be used in many unexpected ways. If you’re into aquaponics – imagine a system like this to heat the thermal mass of your greenhouse to keep the water at an ideal temperature and the fish happy?
Bacteria slow down activity in colder weather so a cheap system like this could keep your system at optimal condition and also be very cheap to run.
Update
Access hole to the drum
Just an update to this story, if you decide to build a rocket stove, two things you may need to know. You will need add some kind of blow-off valve as pressure will build inside the drum and the water temperature will need to be regulated so as to not scald people with boiling water – or indeed explode!
The other thing to be aware of is that you will need to cut an access hole in your structure to reach the screw-on lid on your drum and top up water lost through evaporation or condensation.
Fantastic! I’ll tryti buuld one
My concerns: Copper is very expensive. It will tarnish and degrade when in contact with water. The water running around it will have residue.
the drum pressure / topup is an easy fix, instead of cutting a hole to reach in and unscrew lid topup etc. affix a pipe into the drum that comes out the top of the system so that you can topup the drum when necessary and pressure / steam has somewhere to go
It’s not shown in the picture but presumably the barrel is supported by bricks at each end. Does anyone know what the barrel sits on?
Will be interesting to see how you regulate the temp.Nice job though.
What I wonder is, wouldn’t the drum rust and become all crumbly? I’ve been using an oil drum like that to make biochar and it didn’t take long for it to start falling apart.