First test of the Maputo Ceramic Stove
Crispin Pemberton-Pigott, New Dawn Engineering, August 20, 2006

MCS200

Note: click image to enlarge.

Dear Friends

I have completed a test of the first fully formed Maputo Ceramic Stove (MCS) with 3 litres of water and initially a bit more than 300 gm of charcoal. The unit in the pictures is the final version.

The test was done without any skirt or under-tray to improve efficiency, just a pot and lid sitting on a simple stove.

The water boiled in exactly 30 minutes even though the stove body was wet from being washed (oops).

The specific fuel consumption calculated on the basis of water remaining at the time of boiling (good idea) and water remaining at the end of the simmer (something I think is weird) is:

48 gm per litre of water boiled
16.5 gm per litre simmered at 1 degree below the local boiling point for 45 minutes.

This translates into about 324 gm to boil and simmer 5 litres of water, depending on how you calculate it.

The stove was easy to use. I closed the air hole when it boiled and otherwise did not touch anything at any time.

There was more than 140 gm of charcoal left in the stove at the end of the test. This means it had too much in it to begin with. I was unable to get the temperature to drop below almost the boiling point so I think if it was done again with perhaps 200 or 250 gm of fuel it would come out with a better figure.

The stove in the photos will cost about $3 to manufacture profitably. The material is very low thermal expansion PK11 clay mix fired at 1150 degrees. The whole stove weighs 2230 grammes. The material cost about US$0.40. The grate is removable. The two parts can be formed in a manual press like the Ring Maker.

Maputo Ceramic Stove - 2 samples fired differently
Crispin Pemberton-Pigott, New Dawn Engineering, Swaziland, August 18, 2006

Dear Clay Stove Makers

I am forwarding a photo of two Maputo Ceramic Stoves (MCS) without a grate. One was fired by a thumb-suck method and the other was fired in an oven with a temperature controller.

One of the things I have found is that there is more confidence in the ceramic industry than knowledge.

The two stoves are exactly the same, made from PK11 which is a high feldspar clay, the greater portion being black plastic clay.

You will notice that the darker of the two has a shiny appearance. This is from the melting of the minerals. Looking closely you can see small pock-marks which is where the powdered charcoal burned out (about 10% by weight).

The lighter one is powdery when touched, much lower tone when struck and significantly weaker. The only difference between the two is the firing temperature.