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The reverse-process indoor wood burning stove is a non-catalytic airtight heater. Employing a unique reverse process whereby it not only draws warmed exterior air in to the wood stove for combustion, thus eliminating interior drafts, it also releases fresh outside air through a rear-mounted plenum, where it is heated before entering the premises. This initiates a healthy fresh air exchange system, by introducing oxygen-rich air in to the building. The innovation by Jan Steen started as the Chinook, but later became known as the Sunrise wood stove.
Overview
[edit]The reverse-process stove is a wood-burning stove based on two simple principles.[1] One: It draws in fresh, cooler air from outside the building, then sends that air through interior steel pipes, before releasing it near the rear of the stove for combustion. This prevents cold air being drawn in to the premises. Two: Additional exterior drawn cold, fresh air is released to flow gently up the stove's outside rear plenum, where it is heated and released in to the room at the top of the plenum. This now hot, moist, oxygen-rich air creates a slight positive air pressure within the building.[2] Since this positive air pressure is minimal, there is need for a corresponding exit somewhere up high in the building, to allow the subtle air pressure differential to continue. This double effect, i.e. drawing air for combustion from the exterior as well as introducing fresh air in to the dwelling, makes this unit the 'reverse-process' wood-burning stove.[3] Present day wood heating stoves are "95% more efficient than in earlier times" according to Carol Forsloff.[4]
Additionally, the stove's very large cast iron baffle, when closed, forces the combustion gasses up to the bottom of the baffle, where (temperature allowing) they hopefully ignite. Remnant gasses and air then travel forwards and over the opening at the front of the baffle to be finally released up the rear positioned chimney/pipe.[5][3][6]
It must be understood that the potential British thermal unit (BTU) output allowed by wood-fuel comes mainly from its inherent combustible gasses which are released upon heating. About 70% of these potential heat-releasing BTUs are created by these gasses upon combustion. Many stoves' temperatures do not reach the required 700 plus degrees Fahrenheit to allow these volatile gasses to combust within the confines of the stove. [7] For wood to become optimum fuel, it must have as little moisture content as possible. Differing wood types, i.e. the faster growing, Softwood trees such as cedar and alder, will at best have half the potential BTUs, when compared to the harder, denser growing trees, such as fir and oak, etc.[8]
Additional features, such as a water jacket, can be installed inside the stove.[9] Although the most solid are cast-iron, experience teaches that water heated through a copper coil is better on the skin. Iron in the water makes a skin quite itchy from the build up of iron bacteria.[10] However, it must be realized that anything that hinders the process of combustion, by drawing away degrees of heat from the chamber, interferes with the potential of complete combustion.
History
[edit]Jan Steen is the innovator of the Chinook (later named 'Sunrise') reverse-process wood burning stove. After settling on an island in the Salish Sea on British Columbia's west coast in 1976, the Franklin stove installed in the rented farm house was far from satisfactory.[11] Air leakage through badly fitting doors, a broad and narrow depth combustion chamber and an insatiable need for small pieces of wood because of its short, uncontrolled burns, led Jan to begin his experiments towards the creation of a more efficient vehicle. After 12 prototype models and refining the double airflow configuration, the reverse-process wood-burning stove was born as a far more efficient, time saving, low-tech device. Sadly, with the need for his own foundry, and the industry's costly new safety requirements, the stove never went in to production.[3] The Sunrise 'reverse-process Stove' is a non-catalytic stove which, as a forerunner to the re-introduction of Wood-burning Stoves in the late seventies, was never certified by the United States, or Canada. It was an improvement, created by an entrepreneur at the time. Steen managed to deliver some 75 stoves across Canada with several ending up in Oregon.[3]
Design
[edit]With its large firebox design, and extended cast-iron baffle, this barrel shaped stove works as a highly efficient heat producer. However, its uniqueness continues to lie in its reverse-process air flow of releasing hot, moist oxygen air in to the house. [12][13] Baffles radiate wood gasses back into the heat, allowing for a more complete, secondary combustion. Additionally, the preheated fresh air supply helps keep the primary and secondary combustion temperatures high.[14] As Matthew Stein notes, "the most efficient wood stoves allow for ducting the air intake to draw air directly from outside your home."[5] Open fireplaces are essentially totally in-efficient. While they do radiate heat, giving a sense of immediate comfort to those sitting in front of it, the fact they draw air directly from the room, sending hot air up the chimney, ultimately results in lowering the overall temperature of the premises.[15] This can be verified by reading a temperature gauge located away from the fireplace.
Safety
[edit]Any indoor closed heating appliance used to heat up a building requires the oxygen in fresh air for burning the wood. Upon combustion there is an output of carbon monoxide (CO). Carbon monoxide is a poisonous, odorless gas which exits via the chimney. [16] During the cold winter months, wood stoves are employed for heat. In the 1970s building codes were adopted introducing new construction standards. These required tighter sealed windows and doors, and plastic vapor barriers in walls and ceilings. While this created a tighter sealed barrier to the exterior of the building, it stopped fresh air from entering. This increased the build up of indoor pollution by creating stale air. That in turn led to condensation, with the result of the formation of highly toxic molds and mildews. So with all good intentions, while improving in one area, it created problems in an other.[17][18]
A wood stove employing indoor air for combustion creates problems, since cold air is sucked in to the premise, while on its way to the stove to ultimately disappear up the chimney. The reverse process wood burning stove provides a means of fresh warm air entering the home, rather than creating constant drafts of cold air being drawn in from small openings around windows and doors. By releasing fresh air into the room, the building breathes outwards rather inwards, allowing for a slight positive pressure to build up inside. [19]
A passive solar building design maximizes heating efficiency and due to its tight heat conserving principles and seals must consider adequate air exchange. The building codes for solar homes necessitate a back up heating system. In this regards the highly insulated solar home will also benefit from preheated fresh air entering the home from a back up wood burning stove such as the reverse-process stove.[20]
The National Building Code of Canada mandates new sealed air tight homes with improved air and vapour barriers including a ventilation system which can replace one third of the volume of interior air each hour.[21] Similarly, the American Society of Heating, Refrigerating and Air Conditioning Engineers, recommend that air in a dwelling should be replaced totally every three hours.[22] Fresh air intake is needed to reduce the dangers of indoor pollutants such as particle board formaldehyde releases and radon gas infiltration.[23] With a reverse-process wood burning stove, or fireplace, fresh air is drawn into the home directly, eliminating cold air draft while conserving costs by creating heating efficiency. A reverse-process stove reduces indoor air pollution with its constant intake of fresh air from outdoors.[24]
See also
[edit]- Space heater
- Angithi
- Air-tight stove
- Franklin stove
- Rocket stove
- Daruma stove - Japanese Traditional Wood stove
- Bukhari (heater), traditional Indian wood stove
- Wood-burning stove
References
[edit]- ^ various authors (1910–1912), "Stoves" (digitised online by Chest of Books), Every Woman's Encyclopaedia, vol. 4, London
{{citation}}: CS1 maint: location missing publisher (link) - ^ Sherwood, Gerald E; Stroh, Robert C. (1990), Wood-Frame House Construction (illustrated, reprint ed.), Courier Dover Publications, p. 133, ISBN 0486264017, 9780486264011
{{citation}}: Check|isbn=value: invalid character (help); More than one of|pages=and|page=specified (help) - ^ a b c d Marshall, John (1978), "The Chinook That Roars From its logo to its butterfly gauges, this is a stove unlike any other", Harrowsmith Country Life Magazine (14): 56–59
- ^ Forsloff, Carol (Jul 15, 2009). "Agronomist Recommends Wood Stoves to Heat, Cook and Save Money". Digital Journal. Retrieved 2011-02-11.
- ^ a b Stein, Matthew (2008), When Technology Fails: A Manual for Self-Reliance, Sustainability, and Surviving the Long Emergency, vol. 2, revised, illustrated, Chelsea Green Publishing, p. 356, ISBN 1933392452, 9781933392455
{{citation}}: Check|isbn=value: invalid character (help); More than one of|pages=and|page=specified (help) - ^ Knuth, Judith; Marshall, Paula (2000), Fireplace Decorating and Planning Ideas Better Homes and Gardens Series (illustrated ed.), Better Homes and Gardens: Meredith Books, p. 141, ISBN 0696211025, 9780696211027
{{citation}}: Check|isbn=value: invalid character (help); More than one of|pages=and|page=specified (help) - ^ "Operating a Wood Stove". Residents > Environment > Air Quality > Clean Burning Tips >. City of Kelowna. 2009. Retrieved 2011-02-11.
- ^ "Firewood Success or failure with wood heating depends a lot on the fuel". The Wood Heat Organization Inc. 2011. Retrieved 2011-02-11.
- ^ "Water heater for wood stove", Popular Mechanics Magazine, 156 (3), Popular Mechanics Hearst Magazines: 20, 1981, ISSN 0032-4558
{{citation}}: More than one of|pages=and|page=specified (help); Unknown parameter|month=ignored (help) - ^ Andresen, Bill. "Shock Chlorination for Iron Bacteria Control". Prairie Water News: Volume 2 number 2. Sask Water, Outlook, Saskatchewan. Retrieved 2011-02-17.
- ^ Samuel Y. Edgerton, Jr., "Supplement: The Franklin Stove" in I. Bernard Cohen, Benjamin Franklin's Science (Cambridge, Massachusetts: Harvard University Press, 1990), pages 204-209.
- ^ Wood Stove, Building in Canada, retrieved 2011-02-11
- ^ Bryden, Mark. "Designing Improved Wood Burning Heating Stoves" (PDF). Aprove Research Center. Shell Foundation. Retrieved 2011-02-11.
{{cite web}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ "Advanced combustion stove. Looking at wood stoves page 7" (PDF). The Lure and Lore of Wood. A look at the Yukon's natural fuel. Yukon Development Corporation. Nov. 2002. Retrieved 2011-02-11.
{{cite web}}: Check date values in:|date=(help) - ^ Renner-Smith, Susan (1981). "Fireplace inserts - open fire charm, wood-stove efficiency". Popular Science. Vol. 219. Bonnier Corporation. p. 162. ISSN 0161-7370.
{{cite book}}:|journal=ignored (help); Unknown parameter|month=ignored (help) - ^ Kittle, James L. (1990), Title Home heating and air conditioning systems (digitised online by Google books) (illustrated ed.), McGraw-Hill Professional, p. 144, ISBN 0830632573, 9780830632572
{{citation}}: Check|isbn=value: invalid character (help); More than one of|pages=and|page=specified (help) - ^ Mills, Chris (March 20, 2004). "Ventilation unit proves a breath of fresh air" (PDF). New in Homes. Toronto Star. Retrieved 2011-02-12.
- ^ Gulland, John (2011). "Can a fireplace behave itself in a tight house? Yes, but open fireplaces give all fireplaces a bad name". The Wood Heat Organization Inc. Retrieved 2011-02-11.
- ^ "Combustion Gases in Your Home — Things You Should Know About Combustion Spillage". Canada Mortgage and Housing Corporation. Government of Canada. 1996 – 2011. Retrieved 2011-02-11.
{{cite web}}: Check date values in:|date=(help) - ^
Chiras, Daniel D. (2000), The natural house: a complete guide to healthy, energy-efficient, environmental homes Real Goods Solar Living Bks (illustrated ed.), Chelsea Green Publishing, p. 272, ISBN 1890132578, 9781890132576
{{citation}}: Check|isbn=value: invalid character (help); More than one of|pages=and|page=specified (help) - ^ "Control of Airflow How Your Home Works Ventilation and Airflow Control". Office of Energy Efficiency OEE. Natural Resources Canada NRCan. 2009-04-20. Retrieved 2011-02-11.
- ^
Provey, Joe (2001), "Indoor Air Quality - Fresh Air - is the air in your home safe to breathe? Popular Mechanics", Popular Mechanics Magazine, Hearst Magazines: 116, ISSN 0032-4558
{{citation}}: Unknown parameter|month=ignored (help) - ^ Shurcliff, W A (November 1988), "Air-To-Air Heat-Exchangers for Houses", Annual Review of Energy, 13: 1-22: 1–22, doi:10.1146/annurev.eg.13.110188.000245
- ^ Consumer Product Safety Commission (September 30, 2010). "The Inside Story: A Guide to Indoor Air Quality". Office of Radiation and Indoor Air (6609J). U.S. EPA/Office of Air and Radiation. Retrieved 2011-02-11.
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