A stove is an enclosed space in which fuel is burned to provide heating,
either to heat the space in which the stove is situated, or to heat the stove
itself and items placed on it. This article is principally concerned with
enclosed stoves burning solid fuels for room heating. A kitchen stove is used to
cook food. A wood-burning stove or a coal stove is typically used for heating
a dwelling. Enclosed stoves are more efficient and prevents air from being
sucked from the room into the chimney. Due to concerns about air pollution,
efforts have been made to improve stove design. Pellet stoves, for example are a
type of clean-burning stove. Air-tight stoves more completely combust wood and
eliminate polluting combustion products. In the U.S. since 1992, all wood stoves
being manufactured must limit particulate emission.
Origin The Old English word stofa meant any
individual enclosed space, such as a room, and 'stove' is still occasionally
used in that sense, as in 'stoved in'. Until well into the 19th century 'stove'
was used to mean a single heated room, so that Joseph Bank’s assertion that he
'placed his most precious plants in the stove' or René Descarte’s observation
that he got 'his greatest philosophical inspiration while sitting inside a
stove' are not as odd as they first seem.
In its earliest attestation, cooking was done by roasting meat and tubers in an
open fire. Pottery and other cooking vessels may be placed directly on an
open fire, but setting the vessel on a support, as simple as a base of three
stones, resulted in a stove. The three-stone stove is still widely used
around the world. In some areas it developed into a U-shaped dried mud or
brick enclosure with the opening in the front for fuel and air, sometimes with a
second smaller hole at the rear. Kitchen stove
A kitchen stove, cooker, or cookstove is a kitchen appliance designed for the
purpose of cooking food. Kitchen stoves rely on the application of direct heat
for the cooking process and may also contain an oven underneath or to the
side that is used for baking. Traditionally these have been fueled by
wood and one of the earliest recorded instances of a wood burning kitchen
stove was the so-called stew stove. More modern versions such as the popular
Rayburn Range offer a choice between using wood or gas as the fuel source.
Wood burning stove Coal stoves
The most common stove for heating in the industrial world for almost a century
and a half was the coal stove that burned coal. Coal stoves came in all
sizes and shapes and different operating principles. Coal burns at a much higher
temperature than wood, and coal stoves must be constructed to withstand the
high heat levels. A coal stove can burn either wood or coal, but a wood stove
cannot burn coal unless a grate is supplied. The grate may be removable or
an "extra". This is because coal stoves are fitted
with a grate so allowing part of the combustion air to be admitted below the
fire. The proportion of air admitted above/below the fire depends on the type
of coal. Brown coal and lignites evolve more combustible gases than say
anthracite and so need more air above the fire. The ratio of air above/below
the fire must be carefully adjusted to enable complete .
Efficiency Compared to simple open fires, enclosed
stoves can offer greater efficiency and control. In free air, solid fuels burn
at a temperature of only about 240 °C, which is too low a temperature for
perfect combustion reactions to occur, heat produced through convection is
largely lost, smoke particles are evolved without being fully burned and
the supply of combustion air cannot be readily controlled.
By enclosing the fire in a chamber and connecting it to a chimney, draft is
generated pulling fresh air through the burning fuel. This causes the
temperature of combustion to rise to a point where efficient combustion is
achieved, the enclosure allows the ingress of air to be regulated and
losses by convection are almost eliminated. It also becomes possible,
with ingenious design, to direct the flow of burned gasses inside the stove
such that smoke particles are heated and destroyed.
Enclosing a fire also prevents air from being sucked from the room into the
chimney. This can represent a significant loss of heat as an open
fireplace can pull away many cubic metres of heated air per hour.
Efficiency is generally regarded as the maximum heat output of a stove or fire,
and is usually referred to by manufacturers as the difference between
heat to the room and heat lost up the chimney.
An early improvement was the fire chamber: the fire was enclosed on three
sides by masonry walls and covered by an iron plate. Only in 1735 did the first
design that completely enclosed the fire appear: the Castrol stove of the French
architect François Cuvilliès was a masonry construction with several
fireholes covered by perforated iron plates. It is also known as a stew
stove. Near the end of the 18th century, the design was refined by hanging the
pots in holes through the top iron plate, thus improving heat efficiency
even more. In 1742, Benjamin Franklin invented an
all-metal fireplace in an attempt to improve efficiency. It was still an open
faced fireplace, but improved on efficiency compared to old-fashioned
fireplaces. Some stoves use a catalytic converter
which causes combustion of the gas and smoke particles not previously burned.
Other models use a design that includes firebox insulation, a large baffle to
produce a longer, hotter gas flow path. Modern enclosed stoves are often built
with a window to let out some light and to enable the user to view progress of
the fire. While enclosed stoves are typically more
efficient and controllable than open fires, there are exceptions. The type of
water-heating 'back boiler' open fires commonly used in Ireland, for instance,
can be more than 80% absolute efficiency, while the type of enclosed
stove commonly used in China may be less than 15% efficient.
Material Masonry heaters were developed to
control air flow in stoves. A masonry heater is designed to allow complete
combustion by burning fuels at full-temperature with no restriction of
air inflow. Due to its large thermal mass the captured heat is radiated over
long periods of time without the need of constant firing, and the surface
temperature is generally not dangerous to touch.
Metal stoves came into use in the 18th century. An early and famous example of
a metal stove is the Franklin stove, said to have been invented by Benjamin
Franklin in 1742. It had a labyrinthine path for hot exhaust gases to escape,
thus allowing heat to enter the room instead of going up the chimney. The
Franklin stove, however, was designed for heating, not for cooking. Benjamin
Thompson at the turn to the 19th century was among the first to present a working
metal kitchen stove. His Rumford fireplace used one fire to heat several
pots that were also hung into holes so that they could be heated from the
sides, too. It was even possible to regulate the heat individually for each
hole. His stove was designed for large canteen or castle kitchens, though. It
would take another 30 years until the technology had been refined and the size
of the iron stove been reduced enough for domestic use. Philo Stewart's
Oberlin stove was a much more compact, wood-burning cast-iron stove, patented
in the U.S. in 1834. It became a huge commercial success with some 90,000
units sold in the next 30 years. In Europe, similar designs also appeared in
the 1830s. In the following years, these iron stoves evolved into specialised
cooking appliances with flue pipes connected to the chimney, oven holes,
and installations for heating water. The originally open holes into which the
pots were hung were now covered with concentric iron rings on which the pots
were placed. Depending on the size of the pot or the heat needed, one could
remove the inner rings. Modern stove designs
As concerns about air pollution, deforestation, and climate change have
increased, new efforts have been made to improve stove design. The largest
strides have been made in innovations for biomass burning stoves, such as the
wood burning stoves used in many of the most populous countries. These new
designs address the fundamental problem that wood and other biomass fires
inefficiently consume large amounts of fuel to produce relatively small amounts
of heat, while producing fumes that cause significant indoor and
environmental pollutants. The World Health Organization has documented the
significant number of deaths caused by smoke from home fires. Increases in
efficiency mean that a stove's users can spend less time gathering wood or other
fuels, suffer less emphysema and other lung diseases prevalent in smoke-filled
homes, while reducing deforestation and air pollution.
Corn and pellet stoves and furnaces are a type of biofuel stove. The shelled dry
kernel of corn, also called a corn pellet, creates as much heat as a wood
pellet but generates more ash. "Corn pellet stoves and wood pellet stoves
look the same from the outside. Since they are highly efficient, they don't
need a chimney; instead they can be vented outdoors by a four-inch pipe
through an outside wall and so can be located in any room in the home."
A pellet stove is a type of clean-burning stove which uses small,
biological fuel pellets which are renewable and very clean-burning. Home
heating using a pellet stove is an alternative currently used throughout
the world, with rapid growth in Europe. The pellets are made of renewable
material –- typically wood sawdust or off-cuts. There are currently more than
half a million homes in North America using pellet stoves for heat, and
probably a similar number in Europe. The pellet stove typically uses a feed screw
to transfer pellets from a storage hopper to a combustion chamber. Air is
provided for the combustion by an electric blower. The ignition is
automatic, using a stream of air heated by an electrical element. The rotation
speed of the feeder and the fan speeds can be varied to modulate the heat
output. Other efficient stoves are based on Top
Lit updraft or Woodgas or Smoke Burner stove a principle applied and made
popular by Dr. Thomas Reed, which use small pieces of sticks, chips of wood or
shavings, leaves, etc., as fuel. The efficiency is very high up to 50 percent
as compared to traditional stoves which are 5 to 15 percent on an average.
Stoves fueled by alcohol, such as ethanol, offer another modern,
clean-burning stove option. Ethanol fueled stoves have been made popular
through the work of Project Gaia in Africa, Latin America and the Caribbean.
= Air-tight stove= An air-tight stove is a wood-burning
stove designed to burn solid fuel, traditionally wood, in a controlled
fashion so as to provide for efficient and controlled fuel use, and the
benefits of stable heating or cooking temperatures. They are made of sheet
metal, consisting of a drum-like combustion chamber with airflow openings
that can be open and shut, and a chimney of a metre or more length that turns
from vertical to horizontal so as to leave the tent or building by a side
wall rather than the roof. These stoves are used most often to heat
tents and buildings in winter. Wood or other fuel is put into the stove, lit,
and then air flow is regulated to control the burn. The intake airflow is
either at the level where fuel is added, or below it. The exhaust from the stove
is usually several metres above the combustion chamber.
Most modern air-tight stoves feature a damper at the stove's outlet that can be
closed to force the exhaust through an after burner at the top of the stove, a
heated chamber in which the combustion process continues. Some air-tight stoves
feature a catalytic converter, a platinum grid placed at the stove outlet
to burn remaining fuel that has not been combusted.
Using an air-tight stove initially requires leaving the damper and air
vents open until a bed of coals has been formed. After that, the damper is closed
and the air vent regulated to slow down the burning of the wood. A properly
loaded and controlled air-tight stove will burn safely for eight hours or more
without further attention. These features provide a more complete
combustion of wood and elimination of polluting combustion products. It also
provides for regulation of the intensity of fire by limiting air flow, and for
the fire to create a strong draught or draw up the chimney. This results in
highly efficient fuel usage. Air-tight stoves are a more
sophisticated version of traditional wood-burning stoves. With the advent of
new tent fabrics, they have fallen out of favour for tents because substituting
nylon for canvas creates fire hazards. Emission regulation
Many countries legislate to control emissions. In the U.S. since 1992, the
Phase II EPA Woodstove Regulations require that all wood stoves being
manufactured limit particulate emission to 7.5 grams per hour for stoves with
after burners or 4.1 grams per hour for stoves with catalytic converters.
The burn temperature in modern stoves can increase to the point where
secondary and complete combustion of the fuel takes place. A properly fired
masonry heater has little or no particulate pollution in the exhaust and
does not contribute to the buildup of creosote in the heater flues or the
chimney. Some stoves achieve as little as 1 to 4 grams per hour. This is
roughly 90% less smoke than older stoves, and equates to nearly zero
visible smoke from the chimney. This is largely achieved through causing the
maximum amount of material to combust, which results in a net efficiency of 60
to 70% as contrasted to less than 30% for an open fireplace.
Stove research and development The search for safer, cleaner stoves
remains to many an important if low-profile area of modern technology.
Cook stoves in common use around the world, particularly in Third World
countries, are considered fire hazards and worse: according to the World Health
Organization, a million and a half people die each year from indoor smoke
inhalation caused by faulty stoves. An engineer's "Stove Camp" has been hosted
annually since 1999 by Aprovecho Research Center with the intent of
designing a cheap, efficient, and healthy cook stove for use around the
world. Other engineering societies and philanthropic groups continue to
research and promote improved cook stove designs. A focus on research and
development on improved heating stoves is ongoing and was on display at the
Wood Stove Decathlon in 2013 in Washington DC.
See also References
Further reading Harris, Howell J., “Inventing the U.S.
Stove Industry, c. 1815–1875: Making and Selling the First Universal Consumer
Durable,” Business History Review, 82, 701–33
Harris, Howell, “Coping with Competition: Cooperation and Collusion
in the U.S. Stove Industry, c. 1870–1930,” Business History Review, 86,
657–692. Roth C., “Micro Gasification: Cooking
with gas from biomass“ 1st edition, released January 2011 Published by GIZ
HERA – Poverty-oriented Basic Energy Service
External links Woodheat.org information on woodstoves
Thomas “Electricity” Ahearn, Canada’s Thomas Edison
Early Chinese stoves Early Japanese stoves
Energy Star Appliances Gas cooktops vs induction cooktops vs
electric cooktops