Heat storage and control system for improving the convenience and efficiency of wood burning stoves

Abstract

This claim is an improvement to existing and commercially available domestic heating systems which consist of an outdoor wood burning stove and boiler which recirculate hot water through radiators located inside an inhabited structure or domicile. The inventor proposes the efficiency and convenience of such ‘outdoor wood burning heating systems’ are substantially improved by the addition of a large storage tank for the heated water and an electronic control system. The claimed improvement allows the firebox to be stoked and ignited at a time convenient to the dwelling occupant. Heated water is stored in an insulated water tank until called upon for heating. Combustion is optimized for maximum efficiency and atmospheric emissions are substantially reduced.

Description

BACKGROUND

The use of firewood as a fuel for domestic heating dates from prehistory. In recent years, the increasing cost of fossil fuels has motivated many homeowners, particularly those living in rural areas where firewood is relatively inexpensive and plentiful, to return to wood burning stoves as a primary source of heating their homes during periods of cold weather.

Burning firewood within the confines of an inhabited structure is an inherently dangerous activity. The high risk of errant hot embers, creosote accumulation in the chimney, or other mishaps can result in a catastrophic fire.

In an attempt to mitigate these hazards, a number of commercial innovators have in recent years developed ‘outdoor wood burning stoves’. These outdoor systems place the entire combustion process within a separate enclosure which is located at some safe distance away from the occupied structure. An open boiler or similar arrangement is used to heat water and then transfer heat from the combustion of the firewood to an arrangement of heat exchangers or a radiator(s) located inside an inhabited structure, home, out buildings, and/or providing hot potable water.

Currently available outdoor wood stove heating systems (hereafter referred to as ‘outdoor wood stoves’) typically consist of certain components shared with the claimed improvement, including a “thermostat” (Item 2), “firebox” (Item 10), “boiler” (Item 11), “boiler water recirculating pump” (Item 19), and “radiators” (Item 32).

Background, Continued

Current ‘outdoor wood stoves’ begin operation with the operator loading and igniting fuel in a “firebox” (Item 10). The heat from said combustion causes water in the “boiler” (Item 11) to become heated. Hot water from the “boiler” (Item 11) is circulated by a “boiler water circulation pump” (Item 19). Heated water enters the home or other inhabited structure and is circulated through one or more “radiators” or similar heat exchangers (Item 32) to impart heating to the home interior. The water is circulated so that it returns directly to the “boiler” (Item 11) where it is reheated.

Many commercially available ‘outdoor wood stoves’ attempt to control the quantity of heat provided by the system by monitoring the interior temperature of the home with a “thermostat” (Item 2) and subsequently electrically operating a combustion air flue to increase or decrease the amount of air available for combustion.

Commercially available ‘outdoor wood stoves’ as outlined in ‘paragraphs 003 through 006’ remove undesirable odor, ashes, and housekeeping problems associated with traditional interior fireplaces, fireplace inserts, or other wood burning heating appliances.

Commercially available ‘outdoor wood stoves’ as outlined in ‘paragraphs 003 through 006’ also offer the advantage of consuming low quality firewood which may be undesirable for use in interior wood burning stoves, fireplaces, or appliances.

Background, Continued

While removing the combustion activity from the occupied structure has made currently available outdoor wood burning heating systems safer and desirable to more users, there remain several inherent shortcomings in these systems such as failing to provide a method of storing a significant quantity of heat energy.

Commercially available wood stove heating systems such as those outlined in ‘paragraphs 003 through 006’ have the disadvantage of requiring the operator, homeowner, or tenant to stoke the firebox and/or reignite a fire whenever the current supply of fuel is consumed in the firebox and more heating is desired within the habitation. This often requires the operator to stoke and/or relight the stove several times a day if the home interior is to be maintained at a comfortable or consistent temperature. By contrast, a homeowner or tenant using the Inventor's control and heat storage system could stoke and ignite the firebox during convenient daylight hours rather than awaken during the wee, dark hours of the night to reload or reignite fuel in the firebox.

Current ‘outdoor wood stoves’ require an inconvenient and unacceptably long period of time from when the firebox is stoked and/or reignited to the time the interior of the domicile receives the resulting warmth from renewed combustion.

Background

The inlet flue of most current ‘outdoor wood stoves’ is controlled directly by a thermostat to control the air supply to and resulting intensity of combustion in the firebox. This control strategy is incapable of consistently optimizing combustion efficiency. The attempt by existing systems to extend burn time by restricting air flow to the firebox results in anaerobic ‘roasting’ of the wood and increased smoke and emissions. As a result, ‘outdoor wood stoves’ emit unacceptably high levels of incompletely combusted hydrocarbons, produce an offensive volume of smoke, and consume an excessive quantity of fuel.

The current design of ‘outdoor wood stoves’ does not incorporate sophisticated, multipoint collection of water temperature or combustion data. This lack of critical process information precludes ‘closed loop’ control of the combustion process. Increasing the quantity and quality of data collection inputs to a microprocessor provides an opportunity for various alarms and controls which will improve the efficiency, convenience, reliability and safety of the heating system.

DESCRIPTION OF DRAWINGS

Drawing One—A schematic representation of an outdoor wood burning stove heating system with the addition of the Inventor's claimed improved controls and heat storage system.

EXPLANATION OF SCHEMATIC DRAWING

Item 1 is a microprocessor-based electronic “system control module”. The system control module receives input signals from various temperature sensors, operator inputs, and thermostat signals. Proprietary programming of the “system control module” interprets these inputs to cause desired operation of the improved heating system and achieve the claimed improvements in efficiency and convenience. When a potentially dangerous condition occurs, the controller provides alarm output to the system operator and interrupts the supply of combustion air to the “firebox” (Item 10) by interrupting the control signal to the “remote actuated flue damper” (Item 28).

Item 2 is a commercially available “thermostat” as typically used to control forced air, radiant, and most domestic heating systems.

Item 3 is a commercially available “safety relief valve” as typically installed on hot water heaters, boilers, and many existing outdoor wood stove systems. The “safety relief valve” opens in the event of overheating or over-pressurization of the “boiler” (Item 11).

Item 4 is a commercially available liquid temperature sensor which is used in the claimed invention as a “boiler temperature sensor”. The signal from the “boiler temperature sensor” is an input to the “system control module” (Item 1) for various system optimization functions including an over-temperature warning. The “boiler temperature sensor” input is wired as a fail-safe signal so that a ‘no signal condition’ is programmed as an over-temperature condition.

Explanation of Schematic Drawing, Continued

Item 5 is a commercially available oxygen sensor such as that used to monitor modern, emission compliant automotive engine exhaust streams. This sensor is incorporated in the claimed invention as the “combustion oxygen sensor” to provide an input to the “system control module” (Item 1).

Item 6 is a commercially available liquid pressure switch which is used in the claimed invention as a “boiler return pressure sensor”. The signal from the “boiler return pressure sensor” is an input to the “system control module” (Item 1) to confirm water is entering the “boiler” (Item 11). This input is wired as a fail-safe signal so that a ‘no signal condition’ is programmed as a ‘loss of water to boiler’ condition.

Item 7 is a commercially available liquid temperature sensor which is used in the claimed invention as a “heat reservoir temperature sensor”. The signal from the “heat reservoir temperature sensor” is an input to the “system control module” (Item 1). A low temperature signal from the “heat reservoir temperature sensor” causes the “system control module” (Item 1) to provide an informational alarm and inform the operator that the “firebox” (Item 10) needs to be stoked and ignited.

Explanation of Schematic Drawing, Continued

Item 8 is a commercially available high-temperature sensor which is used in the claimed invention as a “combustion exhaust temperature sensor”. The signal from the “combustion exhaust temperature sensor” is an input to the “system control module” (Item 1). The “system control module” (Item 1) examines this input and adjusts the supply of combustion air via the “remote actuated flue damper” (Item 28) to optimize combustion in the “firebox” (Item 10) and minimize atmospheric emissions from the “chimney” (Item 29).

Item 9 is a commercially available fluid level switch which is used in the claimed invention as the “heat reservoir level switch”. An insufficient water level in the “heat reservoir tank” (Item 22) interrupts the signal from the “heat reservoir level switch”, and results in an alarm condition output from the “system control module” (Item 1).

Item 10 is a schematic representation of the “firebox” of an ‘outdoor wood stove’. Firewood or similar combustible materials are burned within the confines of this “firebox”. No improvement of the “firebox” is claimed but is depicted for reference purposes.

Item 11 is a schematic representation of the boiler of a typical ‘outdoor wood stove’. Water heated within this “boiler” is used to transfer heat to the “domestic structure” (Item 31). No improvement to the “boiler” is claimed but is depicted for reference purposes.

Explanation of Schematic Drawing, Continued

Item 12 is a commercially available three-way valve which serves as a “fast-heat bypass valve”. The “fast-heat bypass valve” determines the destination for heated water exiting from the “boiler” (Item 11) via the “boiler supply line” (Item 14). The heated water may be directed for storage in the “heat reservoir tank (item 22) via the “reservoir return line” (Item 15), or to the “radiators” (Item 32) via the “radiator supply line” (Item 16). Operation of the “fast-heat bypass valve” is controlled by the “system control module” (Item 1).

Item 13 is the “boiler return line”, a pipe enabling the return flow of cool water from the “heat reservoir tank” (Item 22) to the “boiler” (Item 11). The “boiler return line” is a component of current commercially available ‘outdoor wood stoves’ which is modified or rerouted in course of retrofitting this invention to an existing ‘outdoor wood stove’.

Item 14 is the “boiler supply line”, a pipe providing the flow of hot water from the “boiler” (Item 11) to “fast-heat bypass valve” (Item 12). The “boiler supply line” is a component of current commercially available ‘outdoor wood stoves’ which is modified or rerouted in course of implementing this invention to an existing ‘outdoor wood stove’.

Item 15 is the “reservoir return line”, a pipe providing the flow of hot water from the “boiler supply line” (Item 14) through the “fast-heat bypass valve” (Item 12) to replenish the “heat reservoir tank” (Item 22).

Explanation of Schematic Drawing, Continued

Item 16 is the “radiator supply line”, a pipe providing the flow of hot water to the “radiators” (Item 32) from either the “boiler supply line” (Item 14) or the “heat reservoir supply line” (Item 18), depending on the position of the “fast-heat bypass valve” (Item 12).

Item 17 is the “radiator return line”, a pipe which returns cool water exiting the “radiators” (Item 32) and discharges into the “heat reservoir tank” (Item 22).

Item 18 is the “reservoir supply line”, a pipe providing the flow of stored hot water from the “heat reservoir tank” (Item 22) to the “radiators” (Item 32) via the “radiator supply line” (Item 16).

Item 19 is a commercially available motor driven centrifugal water pump similar to that typically supplied as part of currently available ‘outdoor wood stoves’ as a “boiler water circulation pump”. The “boiler water circulation pump” is used to circulate heated water through the heating system. The inlet source of the “boiler water circulation pump” is modified in the course of implementing this invention to an existing ‘outdoor wood stove’ to draw water from the “heat reservoir tank” (Item 22). Operation of the “boiler water circulation pump” is controlled by the “system control module” (Item 1).

Explanation of Schematic Drawing, Continued

Item 20 is a commercially available centrifugal water pump incorporated into the invention as the “reservoir water circulation pump”. The “reservoir water circulation pump” moves warm water from the “heat reservoir tank” Item 22), through the “radiator supply line” (Item 16), radiators (Item 32), and “radiator return line” (Item 17). Operation of the “reservoir water circulation pump” is controlled by the “system control module” (Item 1). The functions of the “reservoir water circulation pump” and “boiler water circulation pump” (Item 19) could be performed with a single pump with certain changes to the system's plumbing but are depicted as two separate pumps in the interest of simplicity in this claim.

Item 21 is “tank insulation” which is applied to the exterior of the “heat reservoir tank” (Item 22) to extend the period of time heat is retained within the “heat reservoir tank” (Item 22) and improve the thermal efficiency of the system. This insulation may be fabricated from a variety of materials, including but not limited to common commercially available fiberglass wool or expanded polystyrene.

Item 22 is a commercially available large capacity water tank, typically with a capacity of 500 to 2,000 gallons. The “heat reservoir tank” provides storage of heated water for a period of up to several days until such time as heating of the “domestic structure” (Item 31) is required.

Item 23 is a commercially available fluid check valve incorporated into the invention as the “fast-heat check valve”. This check valve prevents water from back flowing from the “reservoir supply line” (Item 18) into the “boiler supply line” (Item 14).

Explanation of Schematic Drawing, Continued

Item 24 is a commercially available fluid check valve incorporated into the invention as the “reservoir check valve”. This check valve prevents water from back flowing from the “boiler supply line” (Item 14) into the “reservoir supply line” (Item 18).

Item 25 is a commercially available fluid check valve incorporated into the invention as the “boiler return check valve”. This check valve is important to the safe operation of the system as it insures water cannot backflow out of the “boiler” (Item 11) via the “boiler return line” (Item 13).

Item 26 is a commercially available vacuum relief valve incorporated into the invention as the “vacuum relief valve”. This relief valve is important to the safe operation of the system as it vents air which may become entrapped in the water entering the “boiler” (Item 11) via the “boiler return line” (Item 13).

Item 27 is a commercially available pressure reducing water valve used in the claimed invention as a “make-up water supply valve” to replenish water consumed or lost in the heating system.

Item 28 is a “remote actuated flue damper” which controls the flow of air into the combustion area or “firebox” (Item 10). Controlling the amount of air available for combustion allows the rate and temperature of combustion to be optimized for peak efficiency, improved safety, and/or reduced atmospheric emissions. Automatic and/or electrical actuation of the “remote actuated flue damper” is controlled by the “system control module” (Item 1). In the event that the control signal is interrupted, the flue assumes a closed or ‘fail-safe’ condition.

Explanation of Schematic Drawing, Continued

Item 29 is the “chimney” through which smoke and combustion byproducts exit the “firebox” (Item 10). No improvement to the “chimney” is claimed but is depicted for contextual purposes.

Item 30 is the “firebox enclosure” which contains the “firebox” (Item 10) and generally provides in situ structural support of the “boiler” (Item 11). The “firebox enclosure” may be constructed from steel, firebrick, or similar materials. No improvement is claimed for the “firebox enclosure” but is depicted for contextual purposes.

Item 31 is the “domestic structure”, a domicile, building, or other entity to be heated by the system. No improvement is claimed for the “domestic structure” but is depicted for contextual purposes.

Item 32 is a liquid-to-air heat exchanger consisting of one or more “radiators” through which heated water is pumped to impart convection heating of the interior of a “domestic structure” (Item 31). The “radiators” may be part of the home's original hot-water heating system or component(s) added in the course of installing a commercially available ‘outdoor wood stove’ heating system. No improvement to the “radiators” are claimed but are depicted for contextual purposes.

Explanation of Schematic Drawing, Continued

Item 33 is a “pressurized water source” such as municipal water utility or well water system. The “pressurized water source” is not part of this claim but is depicted for contextual purposes.

Item 34 is the “make-up water supply line”, a pipe providing cool water from the “make-up water supply valve” (Item 27) to the “boiler return line” (Item 13) to replenish water as it is consumed or lost in the claimed heating system.

Description of the Claim and Invention

001) Initiating the heating process—The dwelling occupant or operator places firewood or a similar fuel into the “firebox” (Item 10″) of the claimed ‘improved outdoor wood stove heating system’. The operator ignites the firewood with the resulting heat of combustion causing the water residing in the “boiler” (Item 11) to be heated.

002) Combustion verification—The rising temperature of exhaust gases in the “chimney” (Item 29) causes a signal to be produced by the “combustion exhaust temperature sensor” (Item 8) and produces an input to the “system control module” (Item 1). The rising temperature of the water in the “boiler” (Item 11) produces a signal from the “boiler temperature sensor” (Item 4). These signals and/or other operator inputs into the “system control module” (Item 1) cause the “boiler water circulation pump” (Item 19) to begin operation.

003) Boiler circulation—Water is withdrawn from the “heat reservoir tank” (Item 22) via the “boiler return line” (Item 13) by the “boiler water circulation pump” (Item 19). The circulation of water imparted by the “boiler water circulation pump” (Item 19) moves water through the “boiler” (Item 11), through the “boiler supply line” (Item 14) and toward the “fast-heat bypass valve” (Item 12).

Description of the Claim and Invention, Continued

004) Cold home start-up—In the event that the “thermostat” (Item 2) setting is calling for heat, i.e. the interior of the “domestic structure” (Item 31) is cold, the “system control module” (Item 1) will position the “fast-heat bypass valve” (Item 12) to direct water heated in the manner described in ‘paragraph 003’ to flow into the “radiator supply line” (Item 16). Heated water circulates through the “radiators” (Item 32) and imparts heating to the interior of the “domestic structure” (Item 31). Cool water exits the “radiators” (Item 32) via the “radiator return line” (Item 17) and is discharged into the “heat reservoir tank” (Item 22).

005) Home set-point achieved—Water circulates through the system as described in ‘paragraphs 002 through 004’ until such time as the set point of the “thermostat” (Item 2) is achieved and results in an input to the “system control module” (Item 1).

006) Begin surplus heat storage—In the event combustion is still occurring in the “firebox” (Item 10) and water continues to be heated in the “boiler” (Item 11) as described in ‘paragraph 002’, and the “thermostat” (Item 2) set point is achieved as described in ‘paragraph 005’, the “system control module” (Item 1) will cause the “fast-heat bypass valve” (Item 12) to direct hot water into the “heat reservoir tank” (Item 22) via the “reservoir return line” (Item 15) and begin storing heated water in the “heat reservoir tank” (Item 22) for future use.

Description of the Claim and Invention, Continued

007) Heat storage capacity achieved—The temperature of water contained within the “heat reservoir tank” (Item 22) is continuously monitored by the “heat reservoir temperature sensor” (Item 7) and is an input to the “system control module” (Item 1). In the event combustion continues and the temperature of the water in the “heat reservoir tank” (Item 22) rises above a predetermined level e.g. 170 degrees Fahrenheit, an informational alarm is produced by the “system control module” (Item 1) to alert the operator that no further stoking of the “firebox” (Item 10) is necessary.

008) Heat storage capacity surpassed—The temperature of water contained within the “heat reservoir tank” (Item 22) is continuously monitored by the “heat reservoir temperature sensor” (Item 7) and is an input into the “system control module” (Item 1). In the event combustion continues and the temperature of the water in the “heat reservoir tank” (Item 22) rises above a predetermined level e.g. 190 degrees Fahrenheit, the “system control module” (Item 1) interrupts the control signal to the “remote actuated flue damper” (Item 28) and terminates the flow of combustion air to the “firebox” (Item 10) to prevent overheating of the system.

Description of the Claim and Invention, Continued

009) ‘Call’ for post combustion heating of the home—At such time as the available fuel in the firebox is consumed and depleted, the temperature of water in the “boiler” (Item 11) will fall to a temperature equal to or lower than the temperature of water stored inside the “heat reservoir tank” (Item 22). Under these condition, when the “thermostat” (Item 2) calls for heat, the “system control module” (Item 1) will direct the “reservoir water circulation pump” (Item 20) to operate. Warm water from within the “heat reservoir tank” (Item 22) is drawn by the “reservoir water circulation pump” (Item 20) through the “heat reservoir supply line” (Item 18) through the “heat reservoir check valve” (Item 24) and into the “radiators” (Item 32) located within the “domestic structure”

• • (Item 31). Water exits the “radiators” (Item 32), travels through the “radiator return line” (Item 17) and discharges into the “heat reservoir tank” (Item 22).

010) Post combustion heating of the home ‘achieved’ Water continues to circulate as described in ‘paragraph 009’ until such time as the set point of the “thermostat” (Item 2) is achieved. Operation of the “reservoir water circulation pump” (Item 20) is then interrupted by the “system controller module” (Item 1) until a demand for heating of the “domestic structure” (Item 31) is again called for by the “thermostat” (Item 2).

011) Transfer of heat from reservoir to home—Circulation as described in ‘paragraphs 009 and 010’ continues even when combustion in the “firebox” is limited or nonexistent. The temperature of the water contained by the ‘heat reservoir tank’ (Item 22) will drop as circulation through the “radiators” (Item 32) causes heat to be transferred by convection heating of the “domestic structure” (Item 31) and other losses.

Description of the Claim and Invention, Continued

012) Call for firebox replenishment—At some point the temperature of the water inside the “heat reservoir tank” (Item 22) will drop to a point where it can only provide a few additional hours of heating to the “domestic structure” (Item 31). An input signal at approximately 110 degrees Fahrenheit from the “heat reservoir temperature sensor” (Item 7) to the “system control module” (Item 1) will cause an informational alarm alerting the operator that the “firebox” (Item 10) should be replenished and ignited.

013) Replenishment of boiler water—Safe operation of all boiler systems require that an adequate quantity of water is always present in the boiler. A reliable supply of pressurized water is connected to the claimed system as the “pressurized water source” (Item 34). The “pressurized water source” (Item 34) is connected to a “make-up water supply valve” (Item 27) which in turn provides a reliable supply of water to the “boiler” (Item 11) via the “boiler return line” (Item 13). The pressure setting of the “make-up water supply valve” (Item 27) is adjusted to equal the head pressure of the system as required to maintain proper water level in heat reservoir tank or alternatively the highest point in the system.

014) Active water level monitoring—In certain applications, the water level in the “heat reservoir tank” (Item 22) will be higher than the elevation of the “boiler” (Item 11). The “heat reservoir level switch” (Item 9) monitors the water level inside the “heat reservoir tank” (Item 22) and provides a signal to the “system control module” (Item 1). The system control module produces an alarm condition if the water level inside the “heat reservoir tank (Item 22) is inadequate or could jeopardize the quantity of water available to “boiler” (Item 11).

Description of the Claim and Invention, Continued

015) Redundant protection provided by safety relief valve—In the event the temperature and/or pressure inside the “boiler” (Item 11) reaches a potentially dangerous level, the “safety relief valve” (Item 3) will open and allow hot water and steam to escape into the atmosphere. Operation of the “safety relief valve” (Item 3) is completely independent of the “system control module” (Item 1) or any other system component.

016) In practice, the amount of heat energy generated by the combustion of 40 to 100 pounds of firewood (a typical firebox stoking) exceeds the amount of heat required to return a typical 1,500 to 3,000 square foot home to a comfortable interior temperature. Therefore, combustion in the “firebox” (Item 10) can be expected to continue after achieving the set point of the “thermostat” (Item 2). In the claimed system, heated water continues to flow from the “boiler” (Item 11) through the “fast heat bypass valve” (Item 12) and discharges into the “heat reservoir tank” (Item 22) thus causing the water therein to increase in temperature. The “heat reservoir tank” (Item 22) is surrounded by “tank insulation” (Item 21) allowing the heated water within the tank to remain at an elevated temperature for an extended period of time, thus achieving the Inventor's ‘claim I’ to “Provide a means of storing a substantial quantity of heat energy for a period of up to several days after said heat is produced by the stove's combustion process.”

017) The ability of the claimed system to automatically provide heat to the domicile as described in ‘paragraphs 009, 010, and 011’ even when the firebox and boiler are inactive achieves the inventor's ‘claim II’ to “Provide a means of operating the stove in a manner more convenient for the homeowner's or tenant's lifestyle by allowing fuel loading (stoking) of the firebox and/or initiation of the combustion process (lighting) at a time convenient to the tenant or homeowner rather than at the time heat is required.”

Description of the Claim and Invention, Continued

018) The claimed system utilizes a ‘closed loop’ strategy to continuously monitor inputs such as those from the “combustion temperature sensor” (Item 8) and/or the “combustion oxygen sensor” (Item 5). The “system control module” (Item 1) examines these inputs and is programmed to automatically make appropriate adjustments to the position of the “remote actuated flue damper” (Item 28) to control the amount of air entering the “firebox” (Item 10) to optimize combustion efficiency and safety. The ability of the system to monitor and continuously make adjustments to the combustion process achieves the Inventor's claim III to “Provide an improved method of monitoring and controlling the combustion in the stove firebox, and thus provide the simultaneous benefits of reduced airborne emissions and reduced fuel consumption.”

019) The “system control module” (Item 1) is mounted in a convenient location within the “domestic structure” (Item 31). The tenant, homeowner or operator may readily determine the operating condition of the claimed improved outdoor wood burning stove heating system without leaving the comfort of the home interior, thus achieving the Inventors ‘claim IV’ to “Provide an improved means of monitoring stove operation from a remote location such as from within the interior of the home and thus increase the ease and convenience of operating a wood burning heating system.

Description of the Claim and Invention, Continued

020) If the temperature detected by either the “heat reservoir temperature sensor” (Item 7) or the “boiler temperature sensor” (Item 4) exceed certain preset value, the “system control module” (Item 1) will enter an alarm mode and direct the “remote actuated flue damper” (Item 28) to close and substantially reduce the rate of combustion. The ability of the “system control module” to interpret various inputs and produce alarm condition outputs provides a level of equipment protection and safety not found in current generation ‘outdoor wood stoves’, thus achieving the Inventors ‘claim V’ to “Provide more reliable and sophisticated methods of monitoring and controlling the combustion process and boiler operation and thus reduce the risks of personal injury and/or property damage associated with current generation ‘outdoor wood stoves’ which are relatively unsophisticated'.

Claims

I. Provide a means of storing a substantial quantity of heat energy for a period of up to several days after said heat is produced by the stove's combustion process.

II. Provide a means of operating the stove in a manner more convenient for the homeowner's or tenant's lifestyle by allowing fuel loading (stoking) of the firebox and/or initiation of the combustion process (lighting) at a time convenient to the tenant or homeowner rather than at the time heat is required.

III. Provide an improved method of monitoring and controlling the combustion in the stove firebox, and thus provide the simultaneous benefits of reduced airborne emissions and reduced fuel consumption.

IV. Provide an improved means of monitoring stove operation from a remote location such as from within the interior of the home and thus increase the ease and convenience of operating a wood burning heating system.

V. Provide more reliable and sophisticated methods of monitoring and controlling the combustion process and boiler operation and thus reduce the risks of personal injury and/or property damage associated with current generation, ‘outdoor wood stoves’ which are relatively unsophisticated.