H0W TO OPERATE AN EFFICIENT WOOD BURNING STOVE
ED KEANE 08/09/2013
HOW TO OPERATE AN EFFICIENT WOOD BURNING STOVE
( SUPPLEMENT 3 )
STOVE BUILT IN USA USING REFERENCE DOCUMENT
REFERENCE:
HOW TO BUILD AN EFFICIENT WOOD BURNING STOVE
REVISION (A) 07/16/2013
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Introduction
This supplement (3) is educational information for the stove installers to pass on to the
women who will be the primary user of the efficient wood burning stove. It requires a new
method of cooking which will be a negative because it requires more work preparing wood
and feeding the stove as you cook, however the benefits are many. The benefits are a
healthy environment for the family, less burns and less time foraging for wood. The work
and time added will be offset by the stove efficiency requiring less wood. I can understand
that the woman who cooks wants to do what she is doing and her mother did before her. If
I could design a stove that would fit her life style that would be the best scenario but
studies show that is not possible. To burn wood efficiently there is a need for a rocket
elbow. To remove the toxic smoke from the home I need a smoke path and a chimney. The
stove needs to be raised to protect the children from serious burns. To obtain these benefits
the woman who cooks needs to understand the importance of efficient wood burning
stoves and how they work. The installer needs to understand these instructions so he could
educate the new stove owner on how to use the stove. The main objective using an
efficient wood burning stove is to use the minimum amount of wood to cook a meal. The
women who cook everyday will be the ones who make it work but they need the basics
first and then they can form groups and be the educators.
Preparing Wood
First we need to cut the wood to the proper length about 40 cm long. In the USA we use a
bow saw and a sawbuck see Figure 1. Whatever method you use, make it ease so it will
become a normal routine.
Splitting Wood
If the wood pieces are larger than about 5cm diameter they should be split. When you split
wood you create more exposed area and it burns better. To split wood you will need to
place the log on a hard surface. You will need a steel wedge and a sledgehammer or an axe
see Figure 2. Figure 3 shows wood that has been cut and split and is ready to be stacked
for drying prior to use.
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Drying Wood
The moisture content of fresh cut wood is high. This wood will result in a smoky fire that
will not burn efficiently, the wood needs to be dry. To dry the cut and split wood, stack it
in a sunny spot for at least three months before using. In the rainy season the wood needs
to store in in the home.
Feeding the Stove
Figure 4 is a view at the centerline of the stove that shows how to feed the wood into the
combustion chamber. Only the tips of the wood burn and as tips burn off the wood pieces
need to be pushed gradually into the combustion chamber (CC). Therefore the cook needs
to attend the stove while the food is cooking. If the food is cooking to fast wait before
adding more wood.
If and the wood has been pushed into the combustion chamber a brick can be used to cover
the CC opening while the food shimmers see Figure 5. If the cooking slows down remove
the brick and add more wood and repeat the process. See Figures 6 and 7 for pictures that
demonstrate the process.
Note; If there is excess oxygen wood will burn too quickly and the food will cook too fast.
Wood burning too fast can be the result of too much draft and there is no damper in the
chimney to regulate the draft. A brick covering the CC inlet will help slow down the air
intake to the combustion chamber which will act as a damper.
Cleaning the Chimney
There is little information in the reference document on how to fabricate and build a
chimney that removes the smoke from the home. The chimney needs to be fabricated in
sections so it can be disassembled. Figure 9 shows a young girl cleaning a stove pipe
section with a broom made with stiff straws fastened to a long handle. This is necessary to
prevent buildup of creosote in the stove pipe that can cause a fire. This is a real
maintenance item and may be alien to the user of the new efficient wood burning stove.
Here again education will be important to the operation and maintenance of an efficient
wood burning stoves. This item is important and more attention needs to be given to the
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details for disassembly of the stove pipe. There may be a need for a special group who will
be responsible for fabricating the stove pipe and will perform maintenance and cleaning of
the stove pipe where the new stoves are installed.
Problems
Figure 8 shows some problems with some of the early stoves installed in Sumbawanga.
This is not to be critical, they are important lesson learned and they can be rectified. They
demonstrate the need for education and it is not easily solved. The women who cook have
been using three stone fires their hold life and now they need to change and change is
never easy. The women are an import part of any stove project and they need to be
involved and understand what we are trying to accomplish.
Instructions for Safe Cooking
Herein page 11, are instructions for safe operation of the new efficient wood burning
stove. However a lot more information and education is required for the women who cook
and operate the new stoves. The more they know about the stove and its benefits they can
accept the new life style associated with cooking on a new efficient wood burning stove.
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FIGURE 1 CUTTING FIRE WOOD TO LENGTH IN THE USA
This is just an example, to use this method you would need a bow saw and a sawbuck
(wood support that can easily be built). However you accomplish this task make it ease so
it will become a normal routine.
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FIGURE 2 SPLITTING FIRE WOOD
FIGURE 3 SPLIT WOOD READY TO STORE
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FIGURE 4 SECTION AT CENTERLINE OF STOVE
Section view shows method of feeding fire wood into combustion chamber. A longer piece
of wood is used for pushing. The object is to burn the tips of the wood until it is consumed
and push in the remaining section of wood.
BY HAND
PUSH
WOOD TO
SMOKE
WOOD
COOKING
PLATE
FIR
E
FEED WOOD INTO THE COMBUSTION
CHAMBER
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FIGURE 5 -SECTION AT CENTERLINE OF STOVE WITH BRICK
INSTALLED TO REDUCE AIR INPUT
Once the fire wood has been pushed into the combustion chamber the input air can be
reduced to slow down the cooking and save wood and prevent fast burn that can damage
the stove (combustion chamber, cooking plate and chimney). If the cooking slows down
remove brick and add more wood and repeat process.
LOOSE BRICK
TO REDUCE AIR
INPUT INTO
FIRE
SMOKE
FIRE
STEEL WOOD
RACK
COOKING PLATE
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FIGURE 6 PICTURE AT FACE AT CC INLET SHOWING WOOD
BEING PUSHED INTO THE CC
FIGURE 7 -STOVE PICTURE SHOWING A METHOD OF REDUCING
AIR INPUT USING A BRICK TO ACT AS A DAMPER
A LONG PIECE OF
WOOD TO PUSH
SHORTER PIECES
INTO CC
LOOSE BRICK TO
REDUCE AIR INPUT
INTO COMBUSTION
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Problem
FIGURE 8 EXAMPLE OF A PROBLEM
First the wood needs to be cut in smaller pieces and feed into the stove during cooking.
The black soot on the face of the stove housing indicates the wood was burning outside the
combustion chamber (CC). The stove housing at the CC inlet is eroded from fast burns due
to a high draft from the chimney. This stove with fast burn will eventually damage the
stove housing, which is already happening it can warp the cooking plate and reduce the
life of the chimney. Therefore the instructions herein need to be followed.
It’s good we built prototype stoves and learned that these things can happen.
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(This should be done outside the home because it is a dirty job)
FIGURE 9 A YOUNG GIRL CLEANING A STOVE PIPE
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INSTRUCTIONS FOR SAFE COOKING
1. DO NOT BURN PAPER, LEAVES, TRASH, PLASTICS OR GARBAGE –USE
ONLY WOOD.-
2. BURN ONLY SEASONED WOOD THAT IS DRIED FOR A LONG TIME.-THIS
IS NECESSARY TO PREVENT CREOSOTE AND TAR BUILDUP IN STOVE
PIPE THAT CAN CAUSE FIRES.-
3. USE THE FOLLOWING MAXIMUM WOOD SIZE, LENGTH- ABOUT 50 CM
WITH CROSS SECTIONAL SIZE –WIDTH 5CM- HEIGHT 5 CM- PREPARE
WOOD FOR COOKING BY SPLITTING AND CUTTING TO LENGTH-
4. FEED WOOD ON STEEL RACK INTO COMBUSTION CHAMBER USING A
PIECE OF WOOD- IDEALLY ONLY THE TIPS OF WOOD SHOULD BE
BURNING AND THE FIRE SHOULD BE DIRECTLY UNDER THE POT.
THERE SHOULD BE NO FIRE, EXCEPT IN THE COMBUSTION CHAMBER-
5. REMOVE ALL ASHES FROM THE COMBUSTION CHAMBER BEFORE
STARTING A NEW FIRE AND WHILE OPERATING THE STOVE, IF THE
ASHES FILL UP ABOVE THE TOP OF THE WOOD TRAY.-
6. START FIRES WITH A BUNCH OF VERY THIN STICKS OF WOOD WITH A
FIRE AT ONE END, PLACE THE LIT END INTO THE COMBUSTION
CHAMBER ABOVE WOOD TRY, THEN ADD LARGER PIECES AND SLIDE
THEM ALL THE WAY INTO THE COMBUSTION CHAMBER-THIS IS AN
IMPORTANT TECHNIQUE TO DEVELOP THAT WILL MINIMIZE SMOKE
DURING STARTUP.-
7. WRAP A SCREEN AROUND STOVE PIPE IN AREAS THAT CAN BE
REACHED BY CHILDREN TO PREVENT THEM FROM TOUCHING THE
STOVE PIPE AN RECEIVING BAD BURNS, -THE STOVE PIPE AND THE
STEEL COOKING PLATE TEMPERATURE DURING OPERATION IS ABOUT
230 DEGREES CENTER GRADE. THAT IS OVER TWICE THE
TEMPERATURE OF BOILING WATER