[Stoves] Foyers à bois institutionnels au Cameroun ?

[Crispin Pemberton-Pigott]

Dear Xavier

Many thanks for your overview of your work testing and manufacturing in
Benin - a country we hear nearly nothing from at all.

It is interesting how important height is to cooks how have to deal with
them every day.

You told me something interesting about cooks putting wood into the
combustion chamber from the top and it would be great to hear more about
that, and why they do it.

A similar behaviour was noticed by Cecil Cook in Mongolia. It was related to
getting a high heat during the ignition stage to start cooking sooner.

Regards
Crispin

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"Dear Marc,

I don't know if you intend to manufacture institutional stoves also. Metal
institutional rocket wood stoves are a good solution if you have access to
cheap steel sheet and iron. These stoves have the advantage to have a
smaller production cost than other institutional stoves (in Benin at least,
because metal is cheap, but not necessarily in all countries !) and
production can be centralized in a workshop. Then they can be delivered. No
need to move a full team and all materials to build the stove on site.

These stoves were conceived by Peter Scott, and promoted in GTZ Probec
projects, in Malawi in particular.
I could produce and sell these stoves in Benin, but during the year of the
project, I had to proceed to a few changes. I am willing to share my
technical drawings, and all necessary info so you can make one if you want.

What you have to know is that, in Benin at least, institutional stoves are a
niche market. Make and sell domestic stoves, this is what will work and sell
in large quantities (if they are cheap of course). Institutional stoves
activity can be profitable, on a smaller scale though. I don't think this
activity can suffice to a company.

First, do a thorough market study
-> spend time in kitchens of institutions, restaurants, hotels
	- look at the size of pots where food is cooked
	- look at the cooks gestures and actions, if they stand up, if they
sit down, at what height?)
	- mesure the size of their stoves, the opening of wood feed. Are
these stoves practical to use?
	- is there space for the pots to sit on or around the stove? How is
the food served, or transfered from the pot on the fire to the pot which
will be used for the service?
	- do cooks perform several tasks at the same time or are they
waiting about the fire? Are they regularly tending the fire?
	- how long does the fire last?
	- how many times is the fire set during the day?
	- how much costed the stoves?
	- how long before their deterioration?
	- can they be repaired?
	
-> submit the cooks to a detailed questionnaire
	- what do they like or not about the stoves they use already?
	- what kind of stove would they like to have?
	- what must be according to them the maximum height of a stove? The
minimum height?
	- what must be the maximum duration to boil water (for a given pot
size)

>From what I saw from cooking practices in kitchens of institutions in Benin,
I think the qualities that are researched by cooks in a stove are, by order
of importance:
	1/ fast cooking
	2/ easiness and comfort of use
	3/ durability
	4/ wood savings
	5/ smokes and noxious gas emissions reduction
	6/ stove looks

I excluded price here, since it is not the cooks who buy the stove in
institutions, hotels and restaurants. They only use it, but for domestic
stoves, price is among the most important things.

3 questions are crucial in my opinion :
- stove resistance and durability. Heat is very high in institutional
stoves. It must be taken care of, otherwise stoves will fall to pieces after
a few months.
- stove size. It is very important for users (see criteria number 2 on the
above mentionned list). Size directly determines the stove comfort of use.
Most of the time, the user wants a rather small stove. I made a few changes
on the original drawings so the size could be reduced.
- the stove power. It has to be high, enough so the pot can boil about as
quick as with conventional stoves (see criteria 1). Here again, I modified
the drawings a bit to give more power to the stove (so unfortunately, it
means a bit less fuel savings).

Combustion chamber is the central element of the stove. It has to be
resistant. After experience, I do not advise using inox steel. It is
expensive, and doesn't resist well to an intense and long-lasting fire.
An insulative and light ceramic won't also last long in my opinion.
Especially if it is thin. Users put the stove to the test, they have a
tendency to mistreat it.
We tried to cut clay bricks in 2. The process is extremely long, it is
costly, and result is mediocre. Half-bricks may break, this is what we
encountered.

The best solution: use whole red clay bricks, very resistant and fire proof.
These bricks are used in bread ovens and incinerators. Their size is often
220 X 100 X 60 mm. They must lie on the side. They can be cut in width with
a brick chisel so their size can be adjusted. This will make a massive and
heavy stove. But it will last, and will avoid interventions for repair
(which is painful, I can assure you that).

I can provide you the drawings, which are a modification of Peter Scott
original drawings which can be found on www.rocketstove.org. Once again, I
could not recommend enough to avoid light, thin and fragile ceramics, and
inox steel. Whole and resistant bricks must be put in the stove, and it will
last a long time."