Direct-fired, gas-fueled heater
A direct-fired, gas-fueled heater for greenhouse use. The heater has a base with an airflow assembly disposed within the housing and configured so as to draw a flow of ambient air into the heater through the air inlet matrix, to circulate airflows within the housing, and to direct heated air out of the heater through an air housing exit. Also disposed within the housing is a heat chamber, the heat chamber including an outer wrapper, an upper insert and a lower insert. The lower insert has a lower insert slot having a lower insert slot area and is configured to allow passage of a quenching airflow therethrough to join and mix with a combustion discharge and dilution airflows circulated within the heater. Reduced emissions of certain combustion byproducts are realized.
This application claims priority to provisional U.S. application Ser. No. 60/494,706, filed Aug. 12, 2003, the entire disclosure of which is hereby incorporated by reference.
FIELD OF THE INVENTIONThe invention relates to direct-fired, gas-fueled heaters, and more particularly to direct-fired, gas-fueled heaters for greenhouse heating use.
BACKGROUND OF THE INVENTIONHistorically, greenhouses typically consisted of transparent panes of glass forming a roof to enclose a growing area and draw air from the outside. More recent greenhouses are constructed of a metallic frame structure, utilizing thin wall poly for the roof and side and typically corrugated fiberglass for end panels. Regardless of construction, greenhouses present an enclosed or internal environment where control of the atmosphere and other conditions, e.g., temperature, in the environment is needed in order to protect plants grown or raised therein, providing an optimal environment for desirable plant yield, and to protect the humans who work within the environment.
Due to seasonal temperature fluctuations, particularly during the colder months of the year and more particularly in colder climes, greenhouses are usually provided with a heater to heat the internal environment. This heat may be provided by a variety of different types of heaters such as forced air heaters; vented, indirect-fired unit heaters (sometimes referred to herein as “vented unit heaters”); or direct-fired, gas-fueled heaters (sometimes referred to herein as “direct-fired heaters”). Such heaters typically utilize a gas, such as natural gas or LPG gas (e.g., propane or butane), as a fuel source.
As a result of the combustion of natural gas or LPG gas, combustion byproducts, such as carbon monoxide (CO) nitrogen dioxide (NO2) and ethylene, may enter the greenhouse either through a leak in the exhaust vent system of an indirect-fired (e.g., vented) heater, or directly with the heated air in a direct-fired (e.g., non-vented) heater. These byproducts have the potential for causing illness or other negative or deleterious effects in workers and damaging the plants grown in greenhouses. Carbon monoxide is a combustion byproduct of particular concern to humans in closed environments. Ethylene is a byproduct of particular concern for plants as it can disrupt plant growth cycles, either killing sensitive plants or stunting the growth of less sensitive plants. Nitrogen dioxide is also a combustion byproduct of concern for plants and humans and of general overall concern for ambient air quality of external environments. Carbon dioxide (CO2) is a beneficial combustion byproduct for plants that promotes plant growth but is suspected of negative impacts to the overall global environment.
Greenhouses do not generally have large amounts of natural air exchange and concentrations of deleterious combustion byproducts can accumulate at unacceptable levels. Thus, it would be desirable and advantageous to provide a heater, particularly a direct-fired heater, that produces or emits lower concentrations of harmful gaseous pollutants or byproducts.
Gas-fueled heaters utilized in greenhouses are typically vented unit heaters. Manufacturers of vented unit heaters include Modine, Reznor, Lennox and Sterling. These products have a fuel efficiency of about 80%, and a seasonal operating efficiency of as low as 62% to as high as 78%. The lowest seasonal operating efficiencies are found on “gravity vent” style heaters, where the exhaust vent is open continuously providing for a constant air leakage path. The higher efficiencies are found on relatively more expensive power vent style heaters. Vented unit heaters are generally fuel inefficient compared to direct-fired heaters, and have performance problems due to mechanical failures of such elements as the heat exchanger, burner manifold, gas valves, electronics and other components. The typical life of such a product in a greenhouse is between 5-7 years. Also, if these heaters develop leaks in their vent systems, combustion byproducts harmful to humans and/or plants can accumulate in a greenhouse.
Direct-fired heaters produced by European manufacturers are generally of the “tube style” type with combustion air blowing directly through the unit. The direct-fired heater manufactured by Holland Heater, USA is an example of this type of product, which is typically sold as a CO2 generator, i.e., for limited use and not as a primary heat source. They are physically large and expensive products containing an open flame.
There are several manufacturers of “cabinet-style” direct-fired heaters which are typically utilized in animal containment buildings, but have been of limited use in greenhouses due to emission of high levels of gaseous pollutants. These manufacturers include Hired Hand, Grain Systems International, and LB White. These direct-fired heaters can have thermal efficiencies as high as about 99.96% and, therefore, are generally much more fuel efficient than the vented unit heaters. However, despite the greater fuel efficiency, these heaters can produce undesirably high levels of deleterious combustion byproducts, e.g, CO, NO2, and ethylene. Due to the levels of these combustion byproducts, manufacturers have typically sold their agricultural confinement, direct-fired heaters for limited greenhouse use as an outdoor mounted heater. They can be used in this fashion with a greenhouse having a high amount of natural air exchange in order to minimize the potential effects of the combustion byproducts, particularly in greenhouses where sensitive plants are not being grown. However, in the absence of high amount of natural air exchange, direct fired heaters of this type are of little utility for greenhouse use.
In view of the deficiencies of the above-mentioned vented unit heaters and “cabinet style” direct-fired heaters, it would be desirable to provide a direct-fired heater for use as a heater for enclosed structures such as greenhouses, without need for high amounts of natural air exchanges. Further, it would be desirable that such a heater provide any one or combination of the following: high fuel efficiency, lower product cost, increased operational reliability and durability, reduced emission of deleterious combustion products, and increased CO2 production to stimulate plant growth. Applicants have found that with the direct-fired heater of the invention one or more of the aforementioned benefits can be achieved, particularly high fuel efficiency and reduced emission of deleterious combustion byproducts.
SUMMARY OF THE INVENTIONIn an embodiment of the invention, the direct-fired, gas-fueled heater comprises a base, a housing, an airflow assembly, a heat chamber, and a burner. The base has an air inlet matrix through which ambient air enters the heater. The housing is mounted to the base and is comprised of an outer casing, at least one door, and an air housing exit. The airflow assembly is disposed within the housing and configured so as to draw a flow of ambient air into the heater through the air inlet matrix, to circulate the flow of ambient air as dilution airflows, a primary combustion airflow, and a quenching airflow within the housing, and to direct a combustion discharge stream out of the heater through the air housing exit. The heat chamber is disposed within the housing and is comprised of an outer wrapper, an upper insert and a lower insert, the two inserts being mounted in spaced relationship to define a heat chamber inlet. The burner is disposed within the heat chamber inlet and has at least one discharge port configured with at least one discharge slot from which a combustion discharge emanates and a burner inlet. The burner is attached in spaced relationship to the base to allow a gaseous fuel and the primary combustion airflow to enter the burner through the burner inlet. The lower insert further comprises at least one lower insert slot sized and configured to allow passage of the quenching airflow therethrough to join and mix with the combustion discharge and the dilution airflows to form the combustion discharge stream. The heater is adapted to receive gaseous fuel into the inlet under lower pressure from an external gaseous fuel supply.
In embodiments of the invention, the airflow assembly is mounted to the lower insert in spaced relationship from the outer wrapper. The airflow assembly may be comprised of a fan motor having a shaft, a motor mount, a fan wheel attached to the shaft, an inner scroll disposed between two end panels, the end panels each having a entrance, one entrance facing the heat chamber and being configured to receive the combustion discharge stream and the other entrance facing away from the heat chamber and being configured to receive the fan wheel within the inner scroll, the inner scroll and the two end panels cooperating to define a combustion discharge stream opening that is aligned with the air housing exit when the airflow assembly is mounted within the housing.
The airflow assembly may be mounted in spaced relationship from the outlet of the heat chamber with the space between the airflow assembly and the heat chamber exit defining a mixing zone where dilution airflows, combustion discharge and quenching air flows are intermingled to begin forming the combustion discharge stream.
In other embodiments of the heater of the invention, the heater may further include a gas control assembly adapted for connection to the gaseous fuel supply. The gas control assembly may be comprised of a pressure regulator through which gaseous fuel enters the gas control assembly; a manual shutoff valve; a sediment trap; a gas control valve; and a burner manifold having a burner orifice.
In embodiments of the heater of the invention, the burner orifice has a burner orifice area, the inlet has an inlet area, the lower insert slot has a slot area, and the inlet matrix has an inlet matrix area. For example in an embodiment of the invention utilizing propane as the fuel, the burner orifice has a burner orifice area of about 0.00013 in2 per 1000 BTUH to about 0.00014 in2 per 1000 BTUH; the inlet has an inlet area of about 0.9 in2 per 1000 BTUH to about 1.2 in2 per 1000 BTUH ; the lower insert slot has a slot area of about 0.28 in2 per 1000 BTUH to about 0.31 in2 per 1000 BTUH, and the inlet matrix has an inlet matrix area of between about 0.008 CFM per BTUH to about 0.009 CFM per BTUH. In a further example of an embodiment of the invention utilizing natural gas as the fuel, the burner orifice has a burner orifice area of about 0.00025 in2 per 1000 BTUH to about 0.00027 in2 per 1000 BTUH; the inlet has an inlet area of about 0.9 in2 per 1000 BTUH to about 1.2 in2 per 1000 BTUH; the lower insert slot has a slot area of about 0.28 in2 per 1000 BTUH to about 0.31 in2 per 1000 BTUH, and the inlet matrix has an inlet matrix area of between about 0.008 CFM per BTUH to about 0.009 CFM per BTUH.
The heater of the invention in its various embodiments may incorporate a controller to regulate operational parameters. Thus the heater may include a control box comprised of a panel, an ignition controller, a transformer, a power cord, and a harness. The controller may further comprise additional elements and switches, such as fan motor switch.
BRIEF DESCRIPTION OF THE DRAWINGS
The following detailed description should be read with reference to the drawings, in which like elements in different drawings are numbered identically. The drawings, which are not necessarily to scale, depict selected embodiments and are not intended to limit the scope of the invention.
These major components, as well as some of their subcomponents, are generally manufactured out of heat durable materials, generally known to those skilled in the art, that can tolerate heater operating temperatures. Such materials may include metals and polymeric materials having high softening or melting temperatures. Particularly suitable materials generally will be those additionally exhibiting good to high physical and mechanical durability that is maintained over the life of the product when exposed to the elements and/or the temperature cycles experienced as a result of fuel combustion in heat chamber 40 and circulation of heated air and combustion byproducts throughout the internal environment of the housing. Preferably, the materials forming the heater components and subcomponents additionally exhibit good chemical durability, i.e., rust resistance in a humid environment, corrosion resistance, or ammonia resistance. Examples of suitable materials include, but are not limited to, stainless steel, galvanized steel and pre-painted steel. Some elements or components of heater 10 may be formed of plastic or polymeric materials exhibiting good temperature and/or thermal durability.
Referring to
Referring again to
When assembled, inner scroll 32 is positioned between end panels 33; and fan wheel 35 is disposed within inner scroll 32, through the entrance, and is mounted to the shaft of motor 38, which provides rotational motion to fan wheel 35. Inner scroll 32, in cooperation with end panels 33, defines an airflow opening 34 through which the combustion discharge stream or heated airflow that is drawn into airflow assembly 30 is directed out of heater 10 through air housing exit 29. Airflow assembly 30 may be mounted to the interior of housing 20 and/or to a lower insert 46 of heat chamber 40. When mounted within housing 20, airflow opening 34 is positioned and aligned with air housing exit 29 so that the heated airflow being blown out of airflow assembly 30 by fan 35 may be discharged or exhausted from heater 10 via air housing exit 29.
With reference to
Lower insert slot 49 typically will only partially span the width of lower insert 46. However, in some embodiments, a single lower insert slot 49 may span the entire width of lower insert 46, with lower insert 46 being formed of first and second portions. The first portion being mounted to and within heat chamber 40, and the second portion being mounted and secured to the interior surface of housing 20. A single slot 49 of a desired area is formed with consideration of the overall width of lower insert 46 and the size of the spacing between the first and second portions of lower insert 46.
Referring briefly to
As shown in
When burner 60 is mounted within heat chamber inlet 48 of heater 10, it is attached via burner inlet 64 to base 50 by suitable attachment means known to those skilled in the art so that burner inlet 64 is sufficiently spaced away from the surface of base 50 so as to allow primary combustion air 106 (shown in
Gas is received in heater 10 by a gas control assembly 70 which is connected to an external source or container of gas, e.g., LPG or natural gas (not shown). Gas control assembly 70 regulates the delivery of gas to heater 10. Gas control assembly 70 contains burner manifold 71 which includes single hole manifold orifice 72, and a gas control valve 74, preferably equipped with a power control valve. Manifold 70 is positioned within heater 10 immediately below the inlet area of burner inlet 66 in order to deliver gas to burner 60. As shown in
Gas control valve 74 may be a single-stage control valve that delivers gas at a single pressure or flow rate or it may be a valve that delivers gas at a plurality of pressures or flow rates, such as a dual-stage control valve, a multi-stage control valve, or a modulating control valve. With a single-stage control valve, gas flow is either completely switched on, 100% on, or completely switched off, 100% off. With a dual-stage control valve, gas flow may be, for example 100% off, 50% on (or other percentage less than 100% on), or 100% on. A multi-stage control valve will be understood to regulate gaseous fuel flow rate according to the number of stages provided, providing gas flow a different rates and pressures. With a modulating control valve, gaseous fuel flow rate or pressure is provided as a function of the rate of change of room temperature. Gas delivery assembly 70 may be connected to an external supply of gaseous fuel with standard piping or tubing and connectors, which may include additional valves, regulators, hoses, brackets, various connectors, nipples, and the like such as is commonly known to be used in the art.
Heater 10 may also be equipped with a controller 80. Controller 80 may electrically communicate with an environmental control system. Such a system may receive inputs from temperature, humidity, and/or pollution sensors and determine heating and air exchange needs. In an alternative embodiment, control 80 may electrically communicate with a temperature controlling device, such as a thermostat. As shown in
Controller 80 as shown in
Whether mounted to the heater 10 or structural component, ignition control 84 of controller 80 is in electronic communication with gas control valve 74 and, if provided, with ignition and sensor assembly 90 and temperature limit switch 92, which is preferably a high limit switch. Temperature limit switch 92 and air proving switch 39 may be wired in series to a power terminal of gas control valve 74. If the flame sensor fails to detect or sense a flame, either controller logic may signal the air proving switch to open or temperature limit switch to open in order to shut off the flow of gaseous fuel and thus heater 10. Ignition control 84 may operate as to regulate or control the ignition cycle and/or as a safety monitoring device. Ignition control may be programmed with a basic logic or logic sequence, for example: check air proving switch 39 open, start fan motor 37 and check air proving switch 39 closed, power or energize gas control valve 74 to initiate flow of gaseous fuel to burner 60, start ignition spark sequence, and detect flame. Ignition control 84 may be in electronic communication with a thermostat, and based upon inputs received from the thermostat may signal the heater to shut off, increase gaseous fuel flow to a first flow rate or pressure, e.g., to 50%, increase gaseous fuel flow a second flow rate or pressure, e.g., to 100%, or to otherwise regulate gaseous fuel flow rate according to the number of stages provided in gas control valve 74. Heater 10 may be equipped to run in air circulation mode or in normal heater mode and controller 80 may incorporate an electric switch that can be manually operated to set heater 10 in air circulation mode or heater mode. For example, the switch may comprise a three position rocker switch with “circulate,” “off,” and “heat” positions. Controller 80 may also be configured to electrically communicate with the environmental control to switch the heater 10 between “circulate,” “off,” and “heat” positions. Further, control 80 can be configured to actuate a shutter assembly 134 and an exhaust fan 136, as discussed later herein below relative to
Turning now to
Prior art heater 100 is representative of a direct-fired, gas-fueled heat more typically utilized to heat agricultural animal confinements or greenhouses having a high amount of natural air exchanges. Such prior art heaters typically have a temperature rise of 220° F., with temperature rise being the temperature difference between ambient air 102 entering inlet matrix 52 and the combustion discharge stream exiting air housing exit 29.
With reference to
Providing quenching air 110 that joins with dilution air 104 and the combustion discharge of flame path 108 serves to reduce overall combustion stream temperature to provide acceptable outlet temperatures. This is because quenching air 110 is mixing an additional airflow with the combustion discharge at an earlier point of the combustion cycle thereby lowering the overall flame or combustion discharge temperature. Applicants believe that the lowering of the temperature results in less NO2 being produced as a combustion byproduct. Applicants have found that a temperature rise substantially less than 220° F. is generally sufficient to provide adequate combustion without the increase NO2 production that may be seen from prior art direct fired heaters. A temperature rise of between about 100° F. to about 180° F. is preferable. More preferable is a temperature rise of between about 110° F. to about 120° F., with a temperature rise about 120° F. being even more preferred.
Applicants have found that particular combinations of lower temperature rise, gaseous fuel type specific burner orifice area range, inlet area range, inlet matrix area range, a low gas manifold pressure, a lower insert slot area range, high total airflow into heater 10, in conjunction with the BTU/ft3 of the gaseous fuel type utilized determines the firing rate (BTU per hour) of the heater.
Applicants' attention to and recognition of these interrelationships has resulted in an improved direct-fired heater 10 capable of achieving high fuel efficiency and any one or combination of reduced emission of deleterious combustion gas products, high or increased fuel efficiency, improved CO2 production to stimulate plant growth, lower product cost and lower operating costs. Heater 10 of the invention being of the direct-fired type can achieve at least the same high fuel efficiencies of prior art direct-fired heaters of up to about 99.96% and may possibly achieve even higher fuel efficiencies.
Applicants have found that a lower insert slot area range of between about 0.28 in2 per 1000 BTUH to about 0.31 in2 per 1000 BTUH is suitable. The low gas manifold pressures of not more than about 0.5 psig necessary for the gas supplied to burner inlet 66 of burner 60 can be achieved, in part, with attention to the specific type of gas being utilized and the size, expressed as a “burner orifice area” or “orifice area,” of burner orifice 72 in manifold 71. For example, an orifice area range of 0.00013 to 0.00014 in2 per 1000 BTUH has been found suitable for propane (and may also be suitable for butane) and an orifice area range of 0.00025 to 0.00027 in2 per 1000 BTUH has been found suitable for natural gas. A high amount of total air flow in the order of about 0.008 CFM per BTUH to about 0.009 CFM per BTUH is suitable in order to provide the volume of air necessary to achieve high fuel efficiency that can result in reduced emissions of deleterious combustion byproducts. Applicants have further found that the size of burner inlet 64, expressed as “inlet area,” assists in providing the desired high amount of total airflow to burner 60 to provide the appropriate air/gas mix. An inlet area range of about 0.9 in2 per 1000 BTUH to about 1.2 in2 per 1000 BTUH has been found to be suitable.
With the provision of high total airflow through the heater in combination with the inlet matrix area of inlet matrix 52, gas BTU content, low gas manifold pressure, burner orifice area, and a lower insert slot 49 combinations of various benefits of the invention can be achieved. This can be accomplished in heaters of different firing rates or ratings, for example heaters of 220,000 BTUH and 120,000 BTUH can be produced. Without being bound by theory and although several of the different area ranges were developed as result of experimentation and observation of empirical data gathered, Applicants believe that at least some of these ranges may be capable of being determined based upon or derived from a formulaic calculation or algorithm.
Applicants have confirmed the reduction in deleterious combustion byproducts achieved with heater 10 of the invention by sampling and testing of the heated air exiting from a standard direct-fired heater and from a direct-fired heater according to the invention.
Applicant performed comparative testing of a standard agricultural animal confinement heater and of a heater of the invention. Tests were conducted for carbon monoxide, nitrogen dioxide, ethylene, and carbon dioxide utilizing heater outlet sampling methodology prescribed in IAS Requirements for Gas-Fired Greenhouse Heaters. The heater is operated in an atmosphere having approximately normal oxygen supply, under the specified airflow conditions. Emission levels are based upon the difference between the background or ambient air concentrations in the incoming air to the heater and the levels in the combustion discharge stream or discharge air from the heater. A test duct of the same cross-sectional shape as the heater outlet is used to direct the combustion discharge stream from the heater to gas concentration analysis instruments or to suitable sample container for off-site analysis. Applicants sampled and tested, on-site at Applicants' facility, for CO and CO2 concentrations utilizing a Ultramat 23 analyzer manufactured by Siemens and for NO2 utilizing a high chemiluminesent, NO-NO2-NOX analyzer, Model 42C manufactured by Thermo Environmental Instruments, Inc. For ethylene, samples of discharge air were pulled utilizing a vacuum pump and collected in Tedlar™ bags which were packaged and shipped to the Horticultural Department of North Carolina State University. There the samples were measured utilizing a precision gas chromatograph with a minimum detection level threshold of 0.5 ppb.
The results of the testing is presented in the Table 1 immediately below:
As is apparent from the data in the above table, dramatic reductions in the concentrations of CO, NO2 and ethylene were realized with operation of a direct-fired heater of the invention. Lower CO2 production is realized with levels of production still beneficial to plants and less harmful to humans than from standard agricultural confinement heaters.
As discussed above, heater 10 may be used to heat an enclosed structure, such as a greenhouse 120 as shown in
In the embodiment of
Also shown in
In the embodiment shown in
Heater 10 could also be operated in an air circulation mode, where the heater is not fired but the air flow generating assembly 30 is used to generate air movement. If the heater is located inside the building, as in
While exemplary embodiments of this invention have been illustrated and described, it should be understood that embodiments shown in drawings and described above are merely for illustrative purposes, and are not intended to limit scope of the invention as defined in the appended claims. Further, it will be understood that various changes, adaptations, and modifications might be made without departing from the spirit of the invention and the scope of the appended claims.
Claims
1. A direct-fired, gas-fueled heater, comprising:
- a base having an air inlet matrix through which ambient air enters the heater; a housing mounted to the base, the housing being comprised of an outer casing, at least one door, and an air housing exit; an airflow assembly disposed within the housing and configured so as to draw a flow of ambient air into the heater through the air inlet matrix, to circulate the flow of ambient air as dilution airflows, a primary combustion airflow, and a quenching airflow within the housing, and to a direct a combustion discharge stream out of the heater through the air housing exit; a heat chamber disposed within the housing, the heat chamber being comprised of an outer wrapper, an upper insert and a lower insert, the two inserts being mounted in spaced relationship to define a heat chamber inlet; and a burner disposed within the heat chamber inlet, the burner having a discharge port configured with at least one discharge slot from which a combustion discharge emanates and a burner inlet, the burner being attached in spaced relationship to the base to allow a gaseous fuel and the primary combustion airflow to enter the burner through the burner inlet;
- wherein the lower insert further comprises at least one lower insert slot sized and configured to allow passage of the quenching airflow therethrough to join and mix with the combustion discharge and the dilution airflows to form the combustion discharge stream.
2. The heater of claim 1, wherein the heater is adapted to receive gaseous fuel into the burner inlet at a plurality of pressures from an external gaseous fuel supply.
3. The heater of claim 1, wherein the heater is adapted to receive gaseous fuel into the burner inlet at a lower pressure from an external gaseous fuel supply.
4. The heater of claim 1, wherein the airflow assembly is mounted to the lower insert in spaced relationship from the outer wrapper, the airflow assembly comprising:
- a fan motor having a shaft, a motor mount, a fan wheel attached to the shaft, an inner scroll disposed between two end panels, the end panels each having an entrance, one entrance facing the heat chamber and being configured to receive the combustion discharge stream and the other entrance facing away from the heat chamber and being configured to receive the fan wheel within the inner scroll, the inner scroll and the two end panels cooperating to define a combustion discharge stream opening that is aligned with the air housing exit when the airflow assembly is mounted within the housing.
5. The heater of a claim 4, further comprising a gas control assembly adapted for connection to the gaseous fuel supply, the gas control assembly being comprised of:
- a pressure regulator through which gaseous fuel enters the gas control assembly; a manual shutoff valve; a sediment trap; a gas control valve; a burner manifold having a burner orifice.
6. The heater of claim 5, wherein the burner orifice has a burner orifice area and the inlet has a inlet area, and the lower insert slot has a slot area, and the inlet matrix has an inlet matrix area.
7. The heater of claim 6, wherein gaseous fuel is propane, the burner orifice has a burner orifice area of about 0.00013 in2 per 1000 BTUH to about 0.00014 in2 per 1000 BTUH; the inlet has an inlet area of about 0.9 in2 per 1000 BTUH to about 1.2 in2 per 1000 BTUH; the lower insert slot has a slot area of about 0.28 in2 per 1000 BTUH to about 0.31 in2 per 1000 BTUH, and the inlet matrix has an inlet matrix area of between about 0.008 CFM per BTUH to about 0.009 CFM per BTUH.
8. The heater of claim 6, wherein gaseous fuel is natural gas, the burner orifice has a burner orifice area of about 0.00025 in2 per 1000 BTUH to about 0.00027 in2 per 1000 BTUH; the inlet has an inlet area of about 0.9 in2 per 1000 BTUH to about 1.2 in2 per 1000 BTUH; the lower insert slot has a slot area of about 0.28 in2 per 1000 BTUH to about 0.31 in2 per 1000 BTUH, and the inlet matrix has an inlet matrix area of between about 0.008 CFM per BTUH to about 0.009 CFM per BTUH.
9. The heater of claim 1, wherein the airflow assembly is mounted in spaced relationship from the outlet of the heat chamber, the space between the airflow assembly and the heat chamber exit defining a mixing zone where dilution airflows, combustion discharge and quenching air flows are intermingled to begin forming the combustion discharge stream.
10. The heater of claim 9, further comprising a gas control assembly adapted for connection to the gaseous fuel supply, the gas control assembly being comprised of:
- a pressure regulator through which gaseous fuel enters the gas control assembly; a manual shutoff valve; a sediment trap; a gas control valve; a burner manifold having a burner orifice.
11. The heater of claim 10, wherein the burner orifice has a burner orifice area and the inlet has a inlet area, and the lower insert slot has a slot area, and the inlet matrix has an inlet matrix area.
12. The heater of claim 11, wherein gaseous fuel is propane, the burner orifice has a burner orifice area of about 0.00013 in2 per 1000 BTUH to about 0.00014 in2 per 1000 BTUH; the inlet has an inlet area of about 0.9 in2 per 1000 BTUH to about 1.2 in2 per 1000 BTUH; the lower insert slot has a slot area of about 0.28 in2 per 1000 BTUH to about 0.31 in2 per 1000 BTUH, and the inlet matrix has an inlet matrix area of between about 0.008 CFM per BTUH to about 0.009 CFM per BTUH.
13. The heater of claim 11, wherein gaseous fuel is natural gas, the burner orifice has a burner orifice area of about 0.00025 in2 per 1000 BTUH to about 0.00027 in2 per 1000 BTUH; the inlet has an inlet area of about 0.9 in2 per 1000 BTUH to about 1.2 in2 per 1000 BTUH; the lower insert slot has a slot area of about 0.28 in2 per 1000 BTUH to about 0.31 in2 per 1000 BTUH, and the inlet matrix has an inlet matrix area of between about 0.008 CFM per BTUH to about 0.009 CFM per BTUH.
14. The heater of any one of claims 1-13, the heater further comprising an electronic controller for regulation of heater operational parameters.
15. The heater of any one of claims 1-13, the heater further comprising a control box, the control box comprising a panel, an ignition controller, a transformer, a power cord, and a harness.
16. The heater of claim 15, wherein the control box is in electronic communication with one or more components selected from the group consisting of the gas control valve, fan motor, an air proving switch, an igniter, a temperature limit switch, a fan motor switch, a shutter assembly, and an exhaust fan motor.
17. The heater of claim 1, wherein the heater is mounted within an enclosed structure.
18. The heater of claim 1, wherein the heater is mounted exterior to an enclosed structure.
19. The heater of claim 17 or 18, wherein the enclosed structure further comprises a shutter assembly.
20. The heater of claim 19, wherein the shutter assembly is motor actuated.
21. The heater of claim 17, wherein the enclosed structure further comprises an exhaust fan.
Type: Application
Filed: Aug 12, 2004
Publication Date: Mar 10, 2005
Inventors: John Tomlinson (Onalaska, WI), Carl Lind (Onalaska, WI)
Application Number: 10/917,085