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                  VITA TECHNICAL BULLETIN 51029-BK
                     Double-Drum Sawdust Stove
                        JEFFREY L. WARTLUFT
This bulletin describes an inexpensive home-made stove for burning loose
sawdust.   Constructed from empty oil drums, the stove can heat a room 20
feet square for 6 to 8 hours without tending.
Jeffrey Wartluft is a VITA Volunteer who is a forest products technologist
with the United States Forest Service.  While working on the design for the
sawdust stove, he researched old VITA plans from Afghanistan and compared
them with stoves he had seen while in Chile as a Peace Corps Volunteer.   The
result has been published as Forest Service Research Note NE-208, 1975,
from which this bulletin was taken.
Please send testing results, comments, suggestions and requests for further
information to:
               Technical Bulletins
               VITA Publications Service
               1600 Wilson Boulevard, Suite 500
               Arlington, VA 22209 USA
                                                   ISBN 0-86619-109-7
Volunteers In Technical Assistance
1600 Wilson Boulevard, Suite 500
Arlington, VA 22209, USA
This Technical Bulletin is one of a series of
publications that offer do-it-yourself technology
information on a wide variety of subjects.
Technical Bulletins are idea generators, intended
not so much to provide a definitive answer as to
guide the user's thinking and planning.  Premises
are sound and testing results are provided, if
Users of the information are asked to send us their
evaluations and comments based on their experiences.
Results are incorporated into subsequent
editions, thus providing additional guidelines for
adaptation and use in a greater variety of conditions.
In the United States, sawdust traditionally has been burned in large furnaces
for industrial heating, in smaller furnaces for home heating, and in fireplaces
in the form of compressed logs.  In other parts of the world, loose sawdust has
been burned for years in inexpensive double-drum stoves.  These stoves are well
suited for heating cabins or workshop areas.
The double-drum sawdust stove has other advantages.   It is inexpensive to
fabricate; it uses recycled components; it burns inexpensive fuel; and it heats
a long time with minimum tending.
After seeing these stoves heating homes in Chile and reviewing plans(1) for the
types used in Afghanistan and England, I fabricated an experimental stove
(Figure 1) at the Forest Products Marketing Laboratory in Princeton, West

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Virginia.   Then I learned how to use the stove by firing it with several kinds
of fuel having different moisture contents.
(1) Wood Waste as a Fuel,
Forest Products Research
Lab.   Research
Leaflet 41.  Princes
Risborough, England.
11 pp. 1956.
The experimental double-drum stove was made from a 55-gallon steel drum and a
30-gallon drum, plus about $25 worth of other materials, including stovepipe.
Tools needed for fabrication are tin snips, hammer and anvil, rivet tool, drill
and bit, metal-cutting saber saw, and equipment for brazing with bronze.
The stove (Figure 2) consists of two drums, one inside the other.   A false

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floor inside the outer barrel supports the inner barrel.  A drawer opening
below the false floor provides draft, and the drawer catches dropping ashes,
which are then easily
removed.   Three-inch
holes in the center
of the false floor
and the inner barrel
bottom let air pass
up to the fuel and
let ashes fall into
the drawer.
A tightly fitting lid covers the outer barrel.  Under this lid are about
3 inches of clearance to the top of the inner barrel.  Two 6-inch diameter
stovepipes exit from the outer barrel, allowing smoke to exhaust.   The outer
barrel is supported by three legs to keep excess heat from the floor and
prevent rocking.
The false floor and drawer were fashioned from 20-gage sheet metal.   Drawer
tabs and curved front were fastened with rivets.  The false floor rests on
two parallel 1/2-inch steel rods, which were run through holes on opposite
sides of the outer barrel, and were brazed to it.
Two handles of the lid and one on the drawer were made of 1/2-inch steel
rod, bent to shape, and attached by brazing.
The two joints of stovepipe were brazed to the outer barrel, one near the
top of the stove and the other directly beneath it.  These two horizontal
pipes join into a common vertical pipe.  The upper horizontal pipe is
fitted with a damper.  The vertical pipe is fitted with elbows, straight
lengths, wall or ceiling thimble, and a vent cap to suit the individual
Smaller or larger stoves can be fabricated with heavy-gage sheet metal
(about 14 gage).  The relative sizes of the components should be roughly
proportional to the dimensions of our experimental stove.
The stove should be placed at least 24 inches away from any combustible
wall or floor material.(2)  It should be set on a fireproof floor pad that
extends at least 18 inches in front of the drawer opening.   A wall thimble
or triple wall pipe should be used where the pipe goes through the wall or
ceiling and roof.  The flue pipe should not have long horizontal sections,
as they favor condensation of flue gas.  The condensates leak at the joints
and cause pipe corrosion.
(2) Using Coal and Wood Stoves Safely.  National Fire Protection Association
NFPA HS-8.  12 p. Boston. 1974.
In addition to sawdust, bark residue from sawmills and planer shavings from
planing mills can be burned in the stove.  The limiting factor for fuels is
their moisture content.  Though fuel having more than 100 percent moisture
content (oven-dry basis)(3) will burn, most of the heat is used in evaporating
fuel moisture.  Fuel below 60 percent moisture contents works well.  Fresh
sawdust, shavings, and bark typically have moisture contents ranging from 50
to 110 percent.  The best source of fuel is sawdust or shavings from dried
(3) The water in the material weighs as much as the dry material itself.
Fuel can be stored in a bin or in plastic garbage bags.  If a bin is used,
the inner barrel is either removed and taken to the bin for filling, or a
large bucket is used to transfer the fuel from bin to stove.
How to Use the Stove
A round wooden mold, 3 feet long, tapering from 5 inches to 2 7/8 inches, is
used to shape the fuel charge.
To fill the stove, place the small end of the wooden mold in the hole at the
bottom of the inner barrel.  Then tamp sawdust or bark around it until the
inner barrel is full.  Wet fuel should not be tamped as much as dry fuel.
Carefully remove the mold, leaving a vertical hole in the center of the fuel
charge (Figure 3).

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Before lighting the fire, open the drawer and damper.  Then crumple waste
paper, drop it down the hole in the fuel, and place the lid on the outer
barrel.   Place additional crumpled paper in the drawer and light it; move
the drawer in so the flames will ignite the paper in the hole.
Once the fuel is burning, adjust the drawer and damper to obtain the desirable
rate of burning and output of heat.  Closing the damper forces hot air
to circulate lower in the stove before leaving through the bottom stovepipe.
Thus more heat is transferred to the room and less is lost through the pipe.
CAUTION:   Do not open the lid while the fuel is burning.   Oxygen thus mixed
          with flammable gases can cause a flare-up.
With dry sawdust and a good draft, one charge of this stove can heat a room
20 feet square for 6 to 8 hours with no tending.  Wetter fuel heats less but
lasts longer.  During the first 2 hours of burning, there is enough heat at
the center of the lid to boil water or cook with.  As burning progresses,
the heat on the lid is distributed more toward the rim.
                IN TECHNICAL
                ABOUT VITA
Volunteers in Technical Assistance (VITA) is
a private, nonprofit, international development
organization.   Started in 1959 by a
group of concerned scientists and engineers,
VITA maintains an extensive documentation
center and worldwide roster of volunteer
technical experts.  VITA makes available to
individuals and groups in developing countries
a variety of information and technical
resources aimed at fostering self-sufficiency--needs
assessment and program development
support; by-mail and on-site consulting
services; information systems training.  It
also publishes a quarterly newsletter and a
variety of technical manuals and bulletins.
    For more information, contact:
    1600 Wilson Boulevard, Suite 500
    Arlington, VA 22209 USA

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