Jetstream furnace
Encyclopedia
Jetstream furnaces were an advanced design of wood-fired water heaters conceived by Dr. Richard Hill of the University of Maine
in Orono
, Maine
, USA. The design heated a house to prove the theory, then with government funding become a commercial product.
and people sold it for at least £3000 amazing it was...
The furnace used a forced and induced draft fan to draw combustion air and exhaust gases through the combustion chamber at 1/3 of the speed of sound (100 m/s+). The wood was loaded into a vertical tube which passed through the water jacket into a refractory lined combustion chamber. In this chamber the burning took place and was limited to the ends of the logs. The water jacket prevented the upper parts of the logs from burning so they would gravity feed as the log was consumed.
The products of combustion left the chamber and passed through a narrow ceramic neck which reached temperatures of 2000 degrees F where the gases and tars released by the wood completed their burning. The products then passed through a refractory lined ash chamber which slowed the flow and let ash settle out. From here the hot gases travelled up through the boiler tubes which pass through the water jacket. Turbulators in the tubes improve heat transfer to the water jacket.
All this resulted in total efficiencies as high as 85% but more commonly 75-80% and allowed partly dry unsplit wood to be burned just as effectively and cleanly. The particulate production was 100 times less than airtight stoves of the 1970s and 1980s and was less than representative oil fired furnaces. The Jetstream produced approximately 0.1 grams/hours of soot while EPA certified woodstoves produce up to 7.2 grams per hour. The high combustion chamber velocities do result in fine particulate flyash being ejected from the stack.
The other aspect of Dr. Hill's design was the use of water storage. The furnace only operated at one setting, wide-open burn. A full load of hardwood, approximately 40 lbs would be consumed in four hours and the heat released was stored in water tanks for use through the day.
The Hampton Industries model was designed to produce 120000 BTU.
A Hampton Jetstream Mk II which was set to be the next model offered by Hampton Industries existed in prototype form. It was an upsized version of the unit offered for sale. The only component changed was the diameter of the burning chamber. This was enlarged within the standard casting. The prototype shares many of the design improvements seen in the Kerr Jetstream.
The Tempest was produced by Dumont Industries of Monmouth, ME, USA and is very similar to the Jetstream.
The patent for this device, termed a WoodFired Quick Recovery Water Heater, number 4583495, issued April 22, 1986, is assigned to the Board of Trustees of the University of Maine. There is no current production using the design of this patent. (January, 2008)
Hampton Industries produced the Jetstream from January 1980 to June 1981 producing 500 units. At this point the company ceased operations with unfilled orders for hundreds more stoves and sales approximately 25% higher than projected. It was stated the advertising costs incurred before production depleted the principals in the business and a deal with a venture capitalist fell through at the last minute.
Within 4 weeks of entering receivership, Kerr Controls Ltd of Truro, Nova Scotia had purchased the manufacturing rights and resumed production of the slightly redesigned Jetstream in mid-September 1981 and produced 150 units just in the last quarter of 1981.
The Kerr Jetstream incorporated several updates including the available belt-driven fan replacing the Electrolux vacuum cleaner motor originally used. A removable refractory plug allowing access to the tunnel was added in the back of the unit. An updated control panel was adopted and the option of an electronic panel was added.
The design of the Hampton Industries furnaces and spare parts belong to Kerr Heating Products of Parrsboro, Nova Scotia
. Some molds to replace parts still exist and are available through Kerr Controls or Kerr Heating.
These companies use a process called gasification but the basics of forced draft, twin refractory lined combustion and ash chambers linked by a ceramic or refractory burner nozzle or tube and shell and tube heat exchanger remain common.
University of Maine
The University of Maine is a public research university located in Orono, Maine, United States. The university was established in 1865 as a land grant college and is referred to as the flagship university of the University of Maine System...
in Orono
Orono, Maine
Orono is a town in Penobscot County, Maine, United States. It was first settled in 1774 and named in honor of Chief Joseph Orono of the Penobscot Nation. It is home to The University of Maine. The population was 10,362 at the 2010 census.- Geography :...
, Maine
Maine
Maine is a state in the New England region of the northeastern United States, bordered by the Atlantic Ocean to the east and south, New Hampshire to the west, and the Canadian provinces of Quebec to the northwest and New Brunswick to the northeast. Maine is both the northernmost and easternmost...
, USA. The design heated a house to prove the theory, then with government funding become a commercial product.
Design
it was very rare in those daysand people sold it for at least £3000 amazing it was...
The furnace used a forced and induced draft fan to draw combustion air and exhaust gases through the combustion chamber at 1/3 of the speed of sound (100 m/s+). The wood was loaded into a vertical tube which passed through the water jacket into a refractory lined combustion chamber. In this chamber the burning took place and was limited to the ends of the logs. The water jacket prevented the upper parts of the logs from burning so they would gravity feed as the log was consumed.
The products of combustion left the chamber and passed through a narrow ceramic neck which reached temperatures of 2000 degrees F where the gases and tars released by the wood completed their burning. The products then passed through a refractory lined ash chamber which slowed the flow and let ash settle out. From here the hot gases travelled up through the boiler tubes which pass through the water jacket. Turbulators in the tubes improve heat transfer to the water jacket.
All this resulted in total efficiencies as high as 85% but more commonly 75-80% and allowed partly dry unsplit wood to be burned just as effectively and cleanly. The particulate production was 100 times less than airtight stoves of the 1970s and 1980s and was less than representative oil fired furnaces. The Jetstream produced approximately 0.1 grams/hours of soot while EPA certified woodstoves produce up to 7.2 grams per hour. The high combustion chamber velocities do result in fine particulate flyash being ejected from the stack.
The other aspect of Dr. Hill's design was the use of water storage. The furnace only operated at one setting, wide-open burn. A full load of hardwood, approximately 40 lbs would be consumed in four hours and the heat released was stored in water tanks for use through the day.
The Hampton Industries model was designed to produce 120000 BTU.
A Hampton Jetstream Mk II which was set to be the next model offered by Hampton Industries existed in prototype form. It was an upsized version of the unit offered for sale. The only component changed was the diameter of the burning chamber. This was enlarged within the standard casting. The prototype shares many of the design improvements seen in the Kerr Jetstream.
The Tempest was produced by Dumont Industries of Monmouth, ME, USA and is very similar to the Jetstream.
The patent for this device, termed a WoodFired Quick Recovery Water Heater, number 4583495, issued April 22, 1986, is assigned to the Board of Trustees of the University of Maine. There is no current production using the design of this patent. (January, 2008)
Production history
Hampton Industries of Hampton, PEI, Canada, pursued the design to fit into houses more easily.Hampton Industries produced the Jetstream from January 1980 to June 1981 producing 500 units. At this point the company ceased operations with unfilled orders for hundreds more stoves and sales approximately 25% higher than projected. It was stated the advertising costs incurred before production depleted the principals in the business and a deal with a venture capitalist fell through at the last minute.
Within 4 weeks of entering receivership, Kerr Controls Ltd of Truro, Nova Scotia had purchased the manufacturing rights and resumed production of the slightly redesigned Jetstream in mid-September 1981 and produced 150 units just in the last quarter of 1981.
The Kerr Jetstream incorporated several updates including the available belt-driven fan replacing the Electrolux vacuum cleaner motor originally used. A removable refractory plug allowing access to the tunnel was added in the back of the unit. An updated control panel was adopted and the option of an electronic panel was added.
The design of the Hampton Industries furnaces and spare parts belong to Kerr Heating Products of Parrsboro, Nova Scotia
Nova Scotia
Nova Scotia is one of Canada's three Maritime provinces and is the most populous province in Atlantic Canada. The name of the province is Latin for "New Scotland," but "Nova Scotia" is the recognized, English-language name of the province. The provincial capital is Halifax. Nova Scotia is the...
. Some molds to replace parts still exist and are available through Kerr Controls or Kerr Heating.
Alternate designs
Current (2007) furnaces with similar designs:- Solo Series Wood Gasification Boilers by HS -Tarm
- Alternate Heating Systems (AHS)
- The Greenwood Hydronic Wood Furnace
- Garn WHS
- Kunzel Wood Gasification Boilers
- Alternative Fuel Gasification
- The EKO-LINE and KP-PYRO Boilers and Goliath Commercial Boiler from New Horizon Corporation Inc.
These companies use a process called gasification but the basics of forced draft, twin refractory lined combustion and ash chambers linked by a ceramic or refractory burner nozzle or tube and shell and tube heat exchanger remain common.
External links
See also
- FurnaceFurnaceA furnace is a device used for heating. The name derives from Latin fornax, oven.In American English and Canadian English, the term furnace on its own is generally used to describe household heating systems based on a central furnace , and sometimes as a synonym for kiln, a device used in the...
- Wood furnace
- HydronicsHydronicsHydronics is the use of water as the heat-transfer medium in heating and cooling systems.Some of the oldest and most common examples are steam and hot-water radiators. Historically, in large-scale commercial buildings such as high-rise and campus facilities, a hydronic system may include both a...
- GasificationGasificationGasification is a process that converts organic or fossil based carbonaceous materials into carbon monoxide, hydrogen, carbon dioxide and methane. This is achieved by reacting the material at high temperatures , without combustion, with a controlled amount of oxygen and/or steam...
- Wood gasWood gasWood gas is a syngas fuel which can be used as a fuel for furnaces, stoves and vehicles in place of petrol, diesel or other fuels. During the production process biomass or other carbon-containing materials is gasified within the oxygen-limited environment of a wood gas generator to produce hydrogen...
- Wood gas generatorWood gas generatorA wood gas generator is a gasification unit which converts timber or charcoal into wood gas, a syngas consisting of atmospheric nitrogen, carbon monoxide, hydrogen, traces of methane, and other gases, which - after cooling and filtering - can then be used to power an internal combustion engine or...