US20060266348A1 - Direct fired heater with improved set-up features - Google Patents
Direct fired heater with improved set-up features Download PDFInfo
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- US20060266348A1 US20060266348A1 US11/373,836 US37383606A US2006266348A1 US 20060266348 A1 US20060266348 A1 US 20060266348A1 US 37383606 A US37383606 A US 37383606A US 2006266348 A1 US2006266348 A1 US 2006266348A1
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- Prior art keywords
- burner
- damper
- airflow passage
- air
- downstream
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
- F24H3/00—Air heaters
- F24H3/02—Air heaters with forced circulation
- F24H3/04—Air heaters with forced circulation the air being in direct contact with the heating medium, e.g. electric heating element
- F24H3/0488—Air heaters with forced circulation the air being in direct contact with the heating medium, e.g. electric heating element using fluid fuel
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23D—BURNERS
- F23D91/00—Burners specially adapted for specific applications, not otherwise provided for
- F23D91/02—Burners specially adapted for specific applications, not otherwise provided for for use in particular heating operations
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23D—BURNERS
- F23D2900/00—Special features of, or arrangements for burners using fluid fuels or solid fuels suspended in a carrier gas
- F23D2900/21—Burners specially adapted for a particular use
- F23D2900/21003—Burners specially adapted for a particular use for heating or re-burning air or gas in a duct
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B30/00—Energy efficient heating, ventilation or air conditioning [HVAC]
Definitions
- the present invention relates to a direct fired heater having features to facilitate and improve the operational setup of the heater.
- Heaters for buildings can be either indirect or direct fired.
- the traditional indirect fired heater heats a heat exchanger, such as a tube or plate, for heating air as the air passes over the exchanger.
- a direct fired heater does not have a heat exchanger.
- the burner in a direct fired heater combusts fuel directly into the air stream being heated. The combustion byproducts are released directly into the air stream, which is then directly discharged into the space being heated.
- Direct fired heaters are preferred over indirect fired heaters for heating large and industrial buildings.
- indirect heaters have a low energy efficiency, heat stratification, poor indoor air quality, and require filtration of outside air, dust, and dirt.
- direct fired heaters are generally about 99.8% energy efficient and provide uniform space temperatures due to a slight positive pressure that also forces out smoke, odors, and other contaminates.
- Direct fired heaters also provide better indoor air quality and are lower in cost to operate when compared to indirect heaters because of the high efficiency of the direct fired system.
- Direct fired heaters can be constructed in a variety of configurations. Typically, the burner is arranged upstream of the fan to draw the air through the heater, which is a draw-through configuration. Alternatively, a blow-through configuration can be used where the burner is downstream of the fan or blower discharge.
- the airflow in the direct fired heater is adjusted to achieve optimal combustion efficiency.
- setup of the heater involved a technician taking pressure measurements downstream and upstream from the burner using a portable manometer not permanently attached to the heater and moving the position of a plate inside of the heater in response to the pressure measurements to adjust the airflow.
- the plate was fastened in an adjusted position inside the heater using screws.
- This setup procedure is inconvenient because the technician must stop the operation of the heater to gain access to the interior of the heater, unfasten the plate, adjust its position, restart the heater, take another set of pressure measurements, turn off the heater, adjust the plate position in response to the second set of pressure measurements, and restart the heater.
- this inconvenient process of adjusting the damper in response to pressure measurement is often repeated until optimal airflow is achieved.
- the present invention provides a direct fired heater having features that overcome the above disadvantages.
- An embodiment of the invention involves a direct fired heater comprising a housing forming an airflow passage and the airflow passage having an inlet and an outlet; an air moving device to flow air from the inlet to the outlet; a gas fired burner disposed in the housing; a pivotal airflow damper disposed in the housing relative to the gas fired burner to control the air flow rate through the burner; and an adjusting device for adjusting the damper from outside the airflow passage.
- the housing can have a mixing chamber downstream from the burner for mixing partially combusted air from the burner and uncombusted air that passes through the damper to provide tempered air.
- the pivotal damper is located adjacent to the gas fired burner in the airflow passage and can pivot about an axis transverse relative to the longitudinal axis of the airflow passage.
- the pivotal damper can include a pivotal shaft having an end portion residing outside of the airflow passage.
- the end portion of the pivotal shaft can reside between an interior wall of the housing defining the airflow passage and an exterior wall of the housing, where the exterior wall has an access to the end portion.
- the pivotal position of the damper can be adjusted by means of an adjustable arm provided on the end portion of the shaft.
- the direct fired heater comprises a housing forming an airflow passage and the airflow passage having an inlet and an outlet, an air moving device to flow air from the inlet to the outlet, a gas fired burner disposed in the housing, an airflow damper disposed in the housing relative to the gas fired burner to control the air flow rate through the burner, an upstream sensing probe disposed in the airflow passage upstream of the burner and the damper, a downstream sensing probe disposed in the airflow passage downstream of the burner and the damper, a pressure differential measuring instrument disposed outside of the airflow passage in communication with the upstream sensing probe and the downstream sensing probe for measuring a differential pressure between the upstream sensing probe and the downstream sensing probe, and an adjusting device to adjust the damper in response to the pressure differential measuring instrument.
- the damper can be a conventional damper or a pivotal damper as described above.
- a mixing chamber can also be provided as described above.
- the upstream and downstream sensing probes each can comprise a static or pitot tube.
- the pressure differential measuring instrument can be a fluid containing differential manometer comprising a U shaped conduit having a first tubular arm in communication with the downstream sensing probe, a second tubular arm in communication with the upstream sensing probe, a first fluid level in the first arm, and a second fluid level in the second arm such that the fluid levels indicate differential pressure between the upstream sensing probe and downstream sensing probe.
- a visual indicia is disposed outside of the airflow passage for viewing in conjunction with the first and second fluid levels of the manometer to facilitate adjustment during operational setup of the direct fired heater.
- the direct fired heater also includes a shut-off switch in communication with the upstream sensing probe and the downstream sensing probe where the switch interrupts gas flow to the burner when a pressure differential between the upstream and downstream sensing probe is out of a predetermined pressure differential range.
- the shut-off switch can close a valve in a supply line for supplying gas to the gas fired burner.
- a method embodiment of the invention comprises a method for controlling a direct fired heater where air is drawn through a passage in a housing and a portion of the air is combusted by a burner comprising the steps of sensing pressure upstream and downstream from an airflow damper, and adjusting the plate from outside of the passage until the measured pressure differential upstream and downstream of the damper falls into a predetermined range.
- gas flow to the burner is shut off when the pressure differential is outside of a predetermined range.
- FIG. 1 is a perspective view with portions of the housing broken away to show the internal features of the direct fired heater.
- FIG. 2 is an enlarged, fragmented view of the manometer, shut-off switch, pivotal shaft, adjustable arm, and a locking means disposed on wall 48 .
- FIG. 3 is a greatly enlarged, fragmented of the adjustable arm, end portion of the pivotal shaft, and locking means.
- FIG. 4 is an enlarged, fragmented schematic view of a burner and damper assembly.
- FIG. 5 is an enlarged, fragmented schematic view of a burner, support members for the burner, damper, and air inlet. Interior wall 48 is omitted in both FIGS. 4 and 5 to clearly show the burner and damper assembly.
- FIG. 6 is a greatly enlarged, fragmented view of the indicia and manometer that are be disposed on wall 48 .
- Direct fired heaters can vary greatly and are sometimes considered custom built for the application since the heater is configured for the size of the area to be heated, location of the heater, performance desired, and componentry selected.
- a direct fired heater pursuant to this invention can be mounted upon the roof, adjacent to an exterior wall, or in the interior of the building to be heated. The outside ambient air flows through the heater, where it is heated, and is discharged into the area to be heated.
- a duct can be used to flow the heated air into the building when the heater is remotely mounted from the building.
- the invention is described below and is especially useful in draw-through direct fired heaters but is not limited thereto as other configurations such as blow-through direct fired heaters can benefit from the present invention.
- an embodiment of the invention comprises a direct fired heater having a housing 8 forming an airflow passage 10 and the airflow passage 10 having an inlet 12 and outlet 14 ; an air moving device 16 to flow air from the inlet 12 to the outlet 14 ; a gas fired burner 18 disposed in the airflow passage 10 of the housing 8 to generate tempered air; a pivotal damper 20 disposed in the housing 8 relative to the gas fired burner 18 to control the air flow rate through the burner; and an adjusting device 22 disposed on wall 48 to adjust the damper from outside the airflow passage 10 .
- the housing 8 can be an elongated enclosure having a top wall 2 , bottom wall 3 , front wall 4 , back wall 5 , left side wall 6 , and right side wall 7 .
- the housing 8 can be constructed of aluminized steel walls with a protective finish that are supported by steel framing 9 although other suitable materials can be used for the housing.
- the interior side of the housing walls 2 , 3 , 4 , 5 , 6 , and 7 can form the airflow passage 10 in the housing 8 .
- the inlet 12 can comprise an opening across all of wall 5 or a portion thereof.
- the housing may also include interior walls and exterior walls, for example, to form a single-wall or double-wall housing.
- the inlet 12 can have pretreatment apparatus 44 , FIG. 5 , for pretreating the outside ambient air such.
- the pretreatment apparatus 44 can be a commercially available screen or filter but is not limited thereto as air conditioning coils or other air treatment apparatuses can be used.
- the pretreatment apparatus 44 is shown in FIG. 5 as a filter that can remove contaminates from the outside ambient air.
- Outside ambient air is drawn from the inlet 12 and through the airflow passage 10 .
- the amount of outside air flowing in the airflow passage 10 can range from 100% to 20% by volume with the balance being air from an optional air return that returns interior air of the room or building. When air from the optional air return is used, the return air is mixed with the heated air downstream from the burner 18 .
- the air is drawn to flow through the gas fired burner 18 and the opening 24 adjacent to the burner, for example, as shown in FIG. 1 .
- the air drawn through the burner 18 is used for combustion of the fuel by the burner and provides partially combusted air.
- the gas fired burner 18 is in communication with a gas supply line 88 , which can supply either natural or liquid propane gas or any other suitable gaseous fuel to the burner 18 .
- the gas flows into the burner 18 via the burner manifold 50 , FIG. 5 .
- the burner manifold 50 emits natural or propane gas into an area which is defined by a baffle assembly comprising an upper baffle 54 , lower baffle 56 , and side baffles 58 , 59 .
- the baffles 54 , 56 have a plurality of apertures 52 that allow air from passage 10 to pass through the baffles 54 , 56 .
- the natural or propane gas emitted from the manifold 50 is mixed with air flowing through a plurality of apertures 52 in the upper baffle and lower baffles 54 , 56 .
- the airflow through the burner manifold 50 is kept at a constant velocity during operation of the direct fired heater.
- the apertures 52 function as an air intake for the burner 18 to move air through the baffles 54 , 56 and into the burner 18 .
- the air and gas mixture is ignited by an igniter disposed adjacent the burner manifold 50 to provide partially combusted air.
- the burner 18 can be a commercially available fixed-profile, in-line gas fired burner.
- the gas fired burner 18 can be controlled by a commercially available electronic temperature control system and flame safeguard system although other systems can be used in the practice of the invention.
- electronic temperature control and safeguard systems are commercially available in direct fired heaters manufactured by AbsolutAire Inc. of Kalamazoo, Mich.
- the gas fired burner 18 can be disposed above the damper 20 and mounted to one or more support members 47 as shown in FIG. 5 .
- the support members 47 can be a vertical beam or other suitable support member that supports the gas fired burner when the burner is positioned in an opening 24 in wall 46 as shown in FIGS. 4 and 5 .
- the remainder of the air in airflow passage 10 i.e. the air not drawn through the burner 18 , is uncombusted ambient air and flows through the opening 24 in interior housing wall 46 .
- a pivotal damper 20 can be provided to control the air flow rate through the burner 18 .
- the air flow rate increases through the apertures 52 of the burner 18 as the damper 20 closes relative to opening 24 and the air flow rate decreases through the apertures 52 of the burner 18 as the damper 20 opens relative to opening 24 .
- the damper 20 shown in FIG. 5 is horizontally oriented in opening 24 when open and vertically oriented when closed to adjust air flow restriction therein.
- the damper 20 can reside in opening 24 although the invention envisions that the damper can be located at other locations in the housing to control the air flow rate through the burner.
- the damper 20 is disposed in the housing 8 adjacent to the burner 18 in the opening 24 and in the airflow passage 10 .
- the invention envisions that two openings can be provided in the wall 46 so that the burner can reside in an opening separate from the damper.
- the damper 20 can be a pivotal damper attached to a pivotal shaft 34 to pivot the damper 20 about an axis transverse relative to the longitudinal axis of the airflow passage 10 .
- Shaft 34 can be supported by brackets 38 mounted to the interior wall 46 , which intersects with wall 48 .
- the pivotal shaft includes an end portion 34 e that can reside outside of the airflow passage 10 and can be disposed on interior wall 48 or outside of housing 8 .
- the end portion 34 e extends from a hole in the wall 48 into the space defined by interior wall 48 and exterior wall 7 such that the end portion 34 e resides in the space between interior wall 48 and exterior wall 7 .
- FIG. 1 offered for illustration and not limitation, shows wall 48 broken away with the end portion 34 e residing between interior wall 48 and exterior wall 7 . Access to the space between wall 48 and wall 7 can be provided by access doors 32 , 36 in the outer wall 7 .
- the adjusting device 22 can comprise an adjustable arm 40 on the end portion 34 e to rotate the pivotal shaft 34 , which in turn rotates the damper 20 , for adjustment.
- a fastening means 60 which can be a nut or other suitable fastener, secures the adjustable arm 40 to the end portion 34 e of the shaft 34 .
- the adjustable arm 40 can be an elongated handle that extends from the end portion 34 e for movement forward and backward about the longitudinal axis of the shaft 34 .
- the adjusting device 22 is not limited to an adjustable arm as other arms such as, but not limited to, handles, shafts, cranks, levers, or other devices suitable for adjusting the damper can be used.
- the adjusting device 22 can adjust the air flow rate through the burner to facilitate the set-up of the heater.
- a locking means 42 can be provided to maintain the position of the adjustable arm 40 , which in turn maintains the position of the damper 20 in the airflow passage 10 .
- the locking means 42 is disposed on the distal end of arm 40 and can comprise a wingnut 42 a and a bolt 42 b .
- the threadable shaft 42 s of the bolt 42 b extends through slot 62 in wall 48 with the head of the bolt located behind the interior wall 48 .
- the wingnut 42 a can be tightened about the shaft 42 s to maintain the position of the arm 40 or loosened to move arm 40 for adjusting the position of the damper 20 .
- the slot 62 in wall 48 is arcuate having a track 64 that extends around the edges of the slot 62 .
- the track 64 provides a surface for which the locking means 42 can be secured while received in the slot 62 .
- a visual indicia region 66 is located adjacent the upper peripheral edge of the track 64 and has a series of markings to indicate the position of the damper 34 such as shut, 3 ⁇ 4, 1 ⁇ 2, or open in the opening 24 for adjusting the damper to a position.
- the orientation of the arm 40 , slot 62 , track 64 , and visual indicia region 66 could alternatively be downward or generally vertical depending on the heater configuration. With respect to FIG.
- the adjusting device 22 advantageously allows a technician to adjust the damper 20 from outside the interior wall 48 so that the inconvenient process of stopping the operation and accessing the interior of the heater, unfastening the plate, and manually adjusting the position of the plate in the interior of the heater can be avoided.
- mixing chamber 26 which is downstream of burner 18 and damper 24 , the partially combusted heater air from burner 18 and the uncombusted ambient air passing through the damper 20 are mixed and provide tempered (heated) air.
- the mixing chamber 26 can be formed by walls 6 , 46 , 48 , and 49 . When air from the optional air return is used, the return air is received into the mixing chamber 26 with the uncombusted air.
- Air moving device 16 flows the tempered air from the mixing chamber 26 to outlet 14 to heat the space that will be heated, typically a commercial or industrial facility.
- the air moving device 16 can be disposed in, on, or exterior from housing 8 .
- the air moving device 16 can have an air intake 16 a mounted to wall 49 , which is shown broken away in FIG. 1 .
- the wall 49 can be supported by frames F 1 and F 2 .
- the air moving device 16 can be a commercially available backward-inclined fan or a squirrel cage blower although other devices that move air can be used in practice of the invention.
- the outlet 14 can be disposed on the bottom wall 3 or other walls such as including, but not limited to, wall 4 , 7 , 10 of the housing 8 depending on the configuration of air moving device 16 . While the discharged tempered air does contain combustion byproducts, set-up and operation of the heater pursuant to this invention provides air quality that conforms to the American National Standards Institute Z-83.4 and Z83.18 for indoor air quality.
- the direct fired heater can further include an upstream sensing probe 80 , a downstream sensing probe 82 , and a pressure differential measuring instrument 84 disposed outside of the airflow passage 10 in communication with the upstream sensing probe 80 and the downstream sensing probe 82 .
- the damper 20 in this embodiment can be a pivotal damper as mentioned above or a single slideable blade, a plurality of louvers, or other type of conventional airflow damper.
- the damper can be a motorized damper comprising a motor that is in communication with the shaft 34 to move the shaft 34 , which in turn moves the position of the damper 20 in opening 24 .
- the probes 80 , 82 are disposed outside of the airflow passage 10 and each can be received in an aperture in the interior wall 48 depending on the configuration of the heater.
- the upstream sensing probe 80 is in communication with the airflow upstream of the burner 18 and damper 20 and can protrude into the airflow passage 10 .
- the downstream sensing probe 82 is in communication with the airflow downstream of the burner 18 and damper 20 and can protrude into the mixing chamber 26 .
- the probes 80 , 82 are able to sense any one or a combination of the velocity pressure, total pressure, static pressure, or the air velocity of the airflow in the passage 10 .
- Each probe 80 , 82 is preferably a conventional static tube or pitot tube that senses the velocity pressure although other types of electrical, mechanical, or pneumatic probes can be used in the practice of the invention. Furthermore, it is also envisioned that more than two sensing probes can be used to sense the parameters of the airflow in the passage 10 .
- the pressure differential measuring instrument 84 is communicated to probes 80 , 82 via tubing T 1 , T 2 and displays a reading that corresponds to the pressure differential between upstream sensing probe 80 and downstream sensing probe 82 .
- the pressure differential measuring instrument 84 can be a fluid containing differential manometer, as seen in FIGS. 2 and 6 , comprising a U shaped conduit 68 having a first tubular arm 72 in communication with the downstream sensing probe 82 , a second tubular arm 70 in communication with the upstream sensing probe 80 , a first fluid level 92 in the first arm 72 , and a second fluid level 90 in the second arm 70 .
- the liquid in the manometer can be water or any other suitable liquid.
- the pressure differential measuring instrument can be a commercially available manometer although other pressure differential measuring devices can be used in practice of the invention.
- a visual indicia 86 is located outside of the airflow passage 10 and can be disposed on wall 48 behind the pressure differential measuring instrument 84 .
- the indicia 86 has a first predetermined set region 94 and second predetermined region set 96 relative to which the first and second fluid levels 92 , 90 can be adjusted during operational set up of the direct fired heater.
- the technician adjusts the damper 20 to place the first and second fluid levels 92 , 90 in the first and second predetermined set regions 94 , 96 . For example, when the heater is inoperational, the first and second fluid levels 92 , 90 will be at the middle line 99 of the visual indicia 86 .
- the first and second fluid levels 92 , 90 may be outside regions 94 , 96 such as in the air velocity too high regions 100 , 102 or in the air velocity too low regions 104 , 106 .
- the technician is able to use this information provided by the fluid levels 92 , 90 and the visual indicia 86 to conveniently adjust the damper 20 from outside the housing wall 48 . From this information, the technician can adjust the damper 20 to a position where the first and second fluid levels 92 , 90 are in the “good” predetermined regions 94 , 96 designated on the indicia 86 as “good zones” having a green color to provide desired air quality.
- a shut-off supply switch 98 is communicated to sensing probes 80 , 82 via tubing T 1 and T 2 to receive measurements therefrom.
- the switch 98 compares the pressure differential between the sensing probes 80 , 82 with a predetermined pressure differential range (i.e. good zones) as calibrated by a technician for the specific burner and heater configuration.
- a predetermined pressure differential range i.e. good zones
- the switch 98 sends a signal to a flame relay 97 that sends a signal to close the valve 87 , which interrupts gas flow to the burner 18 .
- the switch 98 and valve 87 can be connected via a connecting means that can be an electrical, mechanical, or pneumatic conduit sufficient to send a signal from the switch 98 and relay 97 to valve 87 .
- the connecting means is preferably conventional electrical wires W that receive an electrical signal.
- the valve 87 has an actuating mechanism that can be mechanical, electrical, or pneumatic to close and open the valve in response to a signal from the shut-off switch 98 to stop gas from reaching the burner 18 and can be a conventional solenoid valve.
- the invention also envisions that more than one valve 87 can be used in practice of this invention.
- the supply line 88 is in communication with a source of gas and can be a conventional pipe for gas having conventional dimensions such as diameters of one inch (1′′), one and a quarter inches (11 ⁇ 4′), etc.
- a source of gas can be a conventional pipe for gas having conventional dimensions such as diameters of one inch (1′′), one and a quarter inches (11 ⁇ 4′), etc.
- This invention envisions a direct fired heater having one or more of the above features to facilitate and improve set-up of the heater for operation to heat a space.
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Abstract
Features of the direct fired heater can facilitate and improve setup and operation thereof. The direct fired heater can include a housing forming an airflow passage and the airflow passage having an inlet and an outlet; an air moving device to flow air from the inlet to the outlet; gas fired burner disposed in the housing; a pivotal airflow damper disposed in the housing relative to the gas fired burner to control the air flow rate through the burner; and an adjusting device for adjusting the damper from outside the airflow passage. Sensing probes disposed in the airflow passage upstream and downstream of the burner and a pressure differential measuring instrument, such as a manometer, disposed outside of airflow passage in communication with the upstream sensing probe and the downstream sensing probe can measure the differential pressure upstream and downstream of the burner. A shut-off switch also in communication with the sensing probes controls a valve that can interrupt gas flow to the burner when the pressure differential between the upstream and downstream sensing probe is out of a predetermined pressure differential range.
Description
- This application claims benefits and priority of provisional application Ser. No. 60/660,920 filed Mar. 11, 2005.
- The present invention relates to a direct fired heater having features to facilitate and improve the operational setup of the heater.
- Heaters for buildings can be either indirect or direct fired. The traditional indirect fired heater heats a heat exchanger, such as a tube or plate, for heating air as the air passes over the exchanger. Unlike an indirect fired heater, a direct fired heater does not have a heat exchanger. The burner in a direct fired heater combusts fuel directly into the air stream being heated. The combustion byproducts are released directly into the air stream, which is then directly discharged into the space being heated.
- Direct fired heaters are preferred over indirect fired heaters for heating large and industrial buildings. In particular, indirect heaters have a low energy efficiency, heat stratification, poor indoor air quality, and require filtration of outside air, dust, and dirt. In contrast, direct fired heaters are generally about 99.8% energy efficient and provide uniform space temperatures due to a slight positive pressure that also forces out smoke, odors, and other contaminates. Direct fired heaters also provide better indoor air quality and are lower in cost to operate when compared to indirect heaters because of the high efficiency of the direct fired system.
- Direct fired heaters can be constructed in a variety of configurations. Typically, the burner is arranged upstream of the fan to draw the air through the heater, which is a draw-through configuration. Alternatively, a blow-through configuration can be used where the burner is downstream of the fan or blower discharge.
- During the operational setup of a direct fired heater, the airflow in the direct fired heater is adjusted to achieve optimal combustion efficiency. In the past, setup of the heater involved a technician taking pressure measurements downstream and upstream from the burner using a portable manometer not permanently attached to the heater and moving the position of a plate inside of the heater in response to the pressure measurements to adjust the airflow. The plate was fastened in an adjusted position inside the heater using screws. This setup procedure is inconvenient because the technician must stop the operation of the heater to gain access to the interior of the heater, unfasten the plate, adjust its position, restart the heater, take another set of pressure measurements, turn off the heater, adjust the plate position in response to the second set of pressure measurements, and restart the heater. Furthermore, this inconvenient process of adjusting the damper in response to pressure measurement is often repeated until optimal airflow is achieved. The present invention provides a direct fired heater having features that overcome the above disadvantages.
- An embodiment of the invention involves a direct fired heater comprising a housing forming an airflow passage and the airflow passage having an inlet and an outlet; an air moving device to flow air from the inlet to the outlet; a gas fired burner disposed in the housing; a pivotal airflow damper disposed in the housing relative to the gas fired burner to control the air flow rate through the burner; and an adjusting device for adjusting the damper from outside the airflow passage. The housing can have a mixing chamber downstream from the burner for mixing partially combusted air from the burner and uncombusted air that passes through the damper to provide tempered air.
- In an illustrative embodiment of the invention, the pivotal damper is located adjacent to the gas fired burner in the airflow passage and can pivot about an axis transverse relative to the longitudinal axis of the airflow passage. The pivotal damper can include a pivotal shaft having an end portion residing outside of the airflow passage. The end portion of the pivotal shaft can reside between an interior wall of the housing defining the airflow passage and an exterior wall of the housing, where the exterior wall has an access to the end portion. The pivotal position of the damper can be adjusted by means of an adjustable arm provided on the end portion of the shaft.
- In another illustrative embodiment of the invention, the direct fired heater comprises a housing forming an airflow passage and the airflow passage having an inlet and an outlet, an air moving device to flow air from the inlet to the outlet, a gas fired burner disposed in the housing, an airflow damper disposed in the housing relative to the gas fired burner to control the air flow rate through the burner, an upstream sensing probe disposed in the airflow passage upstream of the burner and the damper, a downstream sensing probe disposed in the airflow passage downstream of the burner and the damper, a pressure differential measuring instrument disposed outside of the airflow passage in communication with the upstream sensing probe and the downstream sensing probe for measuring a differential pressure between the upstream sensing probe and the downstream sensing probe, and an adjusting device to adjust the damper in response to the pressure differential measuring instrument. The damper can be a conventional damper or a pivotal damper as described above. A mixing chamber can also be provided as described above.
- In an illustrative embodiment of the invention, the upstream and downstream sensing probes each can comprise a static or pitot tube. The pressure differential measuring instrument can be a fluid containing differential manometer comprising a U shaped conduit having a first tubular arm in communication with the downstream sensing probe, a second tubular arm in communication with the upstream sensing probe, a first fluid level in the first arm, and a second fluid level in the second arm such that the fluid levels indicate differential pressure between the upstream sensing probe and downstream sensing probe.
- In another illustrative embodiment, a visual indicia is disposed outside of the airflow passage for viewing in conjunction with the first and second fluid levels of the manometer to facilitate adjustment during operational setup of the direct fired heater.
- In yet another illustrative embodiment of the invention, the direct fired heater also includes a shut-off switch in communication with the upstream sensing probe and the downstream sensing probe where the switch interrupts gas flow to the burner when a pressure differential between the upstream and downstream sensing probe is out of a predetermined pressure differential range. For example, the shut-off switch can close a valve in a supply line for supplying gas to the gas fired burner.
- A method embodiment of the invention comprises a method for controlling a direct fired heater where air is drawn through a passage in a housing and a portion of the air is combusted by a burner comprising the steps of sensing pressure upstream and downstream from an airflow damper, and adjusting the plate from outside of the passage until the measured pressure differential upstream and downstream of the damper falls into a predetermined range. In operation of the direct fired heater, gas flow to the burner is shut off when the pressure differential is outside of a predetermined range.
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FIG. 1 is a perspective view with portions of the housing broken away to show the internal features of the direct fired heater. -
FIG. 2 is an enlarged, fragmented view of the manometer, shut-off switch, pivotal shaft, adjustable arm, and a locking means disposed onwall 48. -
FIG. 3 is a greatly enlarged, fragmented of the adjustable arm, end portion of the pivotal shaft, and locking means. -
FIG. 4 is an enlarged, fragmented schematic view of a burner and damper assembly. -
FIG. 5 is an enlarged, fragmented schematic view of a burner, support members for the burner, damper, and air inlet.Interior wall 48 is omitted in bothFIGS. 4 and 5 to clearly show the burner and damper assembly. -
FIG. 6 is a greatly enlarged, fragmented view of the indicia and manometer that are be disposed onwall 48. - Direct fired heaters can vary greatly and are sometimes considered custom built for the application since the heater is configured for the size of the area to be heated, location of the heater, performance desired, and componentry selected. A direct fired heater pursuant to this invention can be mounted upon the roof, adjacent to an exterior wall, or in the interior of the building to be heated. The outside ambient air flows through the heater, where it is heated, and is discharged into the area to be heated. A duct can be used to flow the heated air into the building when the heater is remotely mounted from the building.
- The invention is described below and is especially useful in draw-through direct fired heaters but is not limited thereto as other configurations such as blow-through direct fired heaters can benefit from the present invention.
- Referring to
FIGS. 1-5 , an embodiment of the invention comprises a direct fired heater having ahousing 8 forming anairflow passage 10 and theairflow passage 10 having aninlet 12 andoutlet 14; anair moving device 16 to flow air from theinlet 12 to theoutlet 14; a gas firedburner 18 disposed in theairflow passage 10 of thehousing 8 to generate tempered air; apivotal damper 20 disposed in thehousing 8 relative to the gas firedburner 18 to control the air flow rate through the burner; and anadjusting device 22 disposed onwall 48 to adjust the damper from outside theairflow passage 10. - In an illustrative embodiment of the invention, the
housing 8 can be an elongated enclosure having atop wall 2,bottom wall 3, front wall 4,back wall 5,left side wall 6, and right side wall 7. Thehousing 8 can be constructed of aluminized steel walls with a protective finish that are supported bysteel framing 9 although other suitable materials can be used for the housing. The interior side of thehousing walls airflow passage 10 in thehousing 8. Theinlet 12 can comprise an opening across all ofwall 5 or a portion thereof. The housing may also include interior walls and exterior walls, for example, to form a single-wall or double-wall housing. - The
inlet 12 can havepretreatment apparatus 44,FIG. 5 , for pretreating the outside ambient air such. Thepretreatment apparatus 44 can be a commercially available screen or filter but is not limited thereto as air conditioning coils or other air treatment apparatuses can be used. For example and not limitation, thepretreatment apparatus 44 is shown inFIG. 5 as a filter that can remove contaminates from the outside ambient air. - Outside ambient air is drawn from the
inlet 12 and through theairflow passage 10. The amount of outside air flowing in theairflow passage 10 can range from 100% to 20% by volume with the balance being air from an optional air return that returns interior air of the room or building. When air from the optional air return is used, the return air is mixed with the heated air downstream from theburner 18. - In the
passage 10, the air is drawn to flow through the gas firedburner 18 and theopening 24 adjacent to the burner, for example, as shown inFIG. 1 . The air drawn through theburner 18 is used for combustion of the fuel by the burner and provides partially combusted air. - The gas fired
burner 18 is in communication with agas supply line 88, which can supply either natural or liquid propane gas or any other suitable gaseous fuel to theburner 18. The gas flows into theburner 18 via theburner manifold 50,FIG. 5 . Theburner manifold 50 emits natural or propane gas into an area which is defined by a baffle assembly comprising anupper baffle 54,lower baffle 56, and side baffles 58, 59. Thebaffles apertures 52 that allow air frompassage 10 to pass through thebaffles apertures 52 in the upper baffle andlower baffles burner manifold 50 is kept at a constant velocity during operation of the direct fired heater. Theapertures 52 function as an air intake for theburner 18 to move air through thebaffles burner 18. The air and gas mixture is ignited by an igniter disposed adjacent theburner manifold 50 to provide partially combusted air. Theburner 18 can be a commercially available fixed-profile, in-line gas fired burner. - For purposes of illustration and not limitation, the gas fired
burner 18 can be controlled by a commercially available electronic temperature control system and flame safeguard system although other systems can be used in the practice of the invention. Such electronic temperature control and safeguard systems are commercially available in direct fired heaters manufactured by AbsolutAire Inc. of Kalamazoo, Mich. - The gas fired
burner 18 can be disposed above thedamper 20 and mounted to one ormore support members 47 as shown inFIG. 5 . Thesupport members 47 can be a vertical beam or other suitable support member that supports the gas fired burner when the burner is positioned in anopening 24 inwall 46 as shown inFIGS. 4 and 5 . - The remainder of the air in
airflow passage 10, i.e. the air not drawn through theburner 18, is uncombusted ambient air and flows through theopening 24 ininterior housing wall 46. - Pursuant to a feature of the invention, a
pivotal damper 20 can be provided to control the air flow rate through theburner 18. The air flow rate increases through theapertures 52 of theburner 18 as thedamper 20 closes relative to opening 24 and the air flow rate decreases through theapertures 52 of theburner 18 as thedamper 20 opens relative toopening 24. For example and not limitation, thedamper 20 shown inFIG. 5 is horizontally oriented in opening 24 when open and vertically oriented when closed to adjust air flow restriction therein. Thedamper 20 can reside in opening 24 although the invention envisions that the damper can be located at other locations in the housing to control the air flow rate through the burner. - The
damper 20 is disposed in thehousing 8 adjacent to theburner 18 in theopening 24 and in theairflow passage 10. The invention envisions that two openings can be provided in thewall 46 so that the burner can reside in an opening separate from the damper. Thedamper 20 can be a pivotal damper attached to apivotal shaft 34 to pivot thedamper 20 about an axis transverse relative to the longitudinal axis of theairflow passage 10.Shaft 34 can be supported bybrackets 38 mounted to theinterior wall 46, which intersects withwall 48. The pivotal shaft includes anend portion 34 e that can reside outside of theairflow passage 10 and can be disposed oninterior wall 48 or outside ofhousing 8. If a single-walled housing is used, theend portion 34 e extends from a hole in thewall 48 into the space defined byinterior wall 48 and exterior wall 7 such that theend portion 34 e resides in the space betweeninterior wall 48 and exterior wall 7.FIG. 1 , offered for illustration and not limitation, showswall 48 broken away with theend portion 34 e residing betweeninterior wall 48 and exterior wall 7. Access to the space betweenwall 48 and wall 7 can be provided byaccess doors - Referring to
FIG. 3 , the adjustingdevice 22 can comprise anadjustable arm 40 on theend portion 34 e to rotate thepivotal shaft 34, which in turn rotates thedamper 20, for adjustment. A fastening means 60, which can be a nut or other suitable fastener, secures theadjustable arm 40 to theend portion 34 e of theshaft 34. Theadjustable arm 40 can be an elongated handle that extends from theend portion 34 e for movement forward and backward about the longitudinal axis of theshaft 34. The adjustingdevice 22 is not limited to an adjustable arm as other arms such as, but not limited to, handles, shafts, cranks, levers, or other devices suitable for adjusting the damper can be used. The adjustingdevice 22 can adjust the air flow rate through the burner to facilitate the set-up of the heater. - A locking means 42 can be provided to maintain the position of the
adjustable arm 40, which in turn maintains the position of thedamper 20 in theairflow passage 10. The locking means 42 is disposed on the distal end ofarm 40 and can comprise awingnut 42 a and abolt 42 b. Thethreadable shaft 42 s of thebolt 42 b extends throughslot 62 inwall 48 with the head of the bolt located behind theinterior wall 48. Thewingnut 42 a can be tightened about theshaft 42 s to maintain the position of thearm 40 or loosened to movearm 40 for adjusting the position of thedamper 20. Theslot 62 inwall 48 is arcuate having atrack 64 that extends around the edges of theslot 62. Thetrack 64 provides a surface for which the locking means 42 can be secured while received in theslot 62. Avisual indicia region 66 is located adjacent the upper peripheral edge of thetrack 64 and has a series of markings to indicate the position of thedamper 34 such as shut, ¾, ½, or open in theopening 24 for adjusting the damper to a position. The orientation of thearm 40,slot 62,track 64, andvisual indicia region 66 could alternatively be downward or generally vertical depending on the heater configuration. With respect toFIG. 1 , the adjustingdevice 22 advantageously allows a technician to adjust thedamper 20 from outside theinterior wall 48 so that the inconvenient process of stopping the operation and accessing the interior of the heater, unfastening the plate, and manually adjusting the position of the plate in the interior of the heater can be avoided. - In mixing
chamber 26, which is downstream ofburner 18 anddamper 24, the partially combusted heater air fromburner 18 and the uncombusted ambient air passing through thedamper 20 are mixed and provide tempered (heated) air. As shown inFIG. 1 and offered for illustration and not limitation, the mixingchamber 26 can be formed bywalls chamber 26 with the uncombusted air. -
Air moving device 16 flows the tempered air from the mixingchamber 26 tooutlet 14 to heat the space that will be heated, typically a commercial or industrial facility. Theair moving device 16 can be disposed in, on, or exterior fromhousing 8. Theair moving device 16 can have anair intake 16 a mounted to wall 49, which is shown broken away inFIG. 1 . Thewall 49 can be supported by frames F1 and F2. For purposes of illustration and not limitation, theair moving device 16 can be a commercially available backward-inclined fan or a squirrel cage blower although other devices that move air can be used in practice of the invention. Theoutlet 14 can be disposed on thebottom wall 3 or other walls such as including, but not limited to,wall 4, 7, 10 of thehousing 8 depending on the configuration ofair moving device 16. While the discharged tempered air does contain combustion byproducts, set-up and operation of the heater pursuant to this invention provides air quality that conforms to the American National Standards Institute Z-83.4 and Z83.18 for indoor air quality. - Pursuant to another feature of the invention, as shown in
FIGS. 2 and 6 , the direct fired heater can further include anupstream sensing probe 80, adownstream sensing probe 82, and a pressure differential measuringinstrument 84 disposed outside of theairflow passage 10 in communication with theupstream sensing probe 80 and thedownstream sensing probe 82. - The
damper 20 in this embodiment can be a pivotal damper as mentioned above or a single slideable blade, a plurality of louvers, or other type of conventional airflow damper. In still another embodiment, the damper can be a motorized damper comprising a motor that is in communication with theshaft 34 to move theshaft 34, which in turn moves the position of thedamper 20 inopening 24. - The
probes airflow passage 10 and each can be received in an aperture in theinterior wall 48 depending on the configuration of the heater. Theupstream sensing probe 80 is in communication with the airflow upstream of theburner 18 anddamper 20 and can protrude into theairflow passage 10. Thedownstream sensing probe 82 is in communication with the airflow downstream of theburner 18 anddamper 20 and can protrude into the mixingchamber 26. Theprobes passage 10. Eachprobe passage 10. - The pressure differential measuring
instrument 84 is communicated toprobes upstream sensing probe 80 anddownstream sensing probe 82. The pressure differential measuringinstrument 84 can be a fluid containing differential manometer, as seen inFIGS. 2 and 6 , comprising a U shapedconduit 68 having a firsttubular arm 72 in communication with thedownstream sensing probe 82, a secondtubular arm 70 in communication with theupstream sensing probe 80, afirst fluid level 92 in thefirst arm 72, and asecond fluid level 90 in thesecond arm 70. The liquid in the manometer can be water or any other suitable liquid. For purposes of illustration and not limitation, the pressure differential measuring instrument can be a commercially available manometer although other pressure differential measuring devices can be used in practice of the invention. - A
visual indicia 86 is located outside of theairflow passage 10 and can be disposed onwall 48 behind the pressure differential measuringinstrument 84. Theindicia 86 has a firstpredetermined set region 94 and second predetermined region set 96 relative to which the first andsecond fluid levels damper 20 to place the first andsecond fluid levels predetermined set regions second fluid levels middle line 99 of thevisual indicia 86. When the heater is turned on without adjustment, the first andsecond fluid levels outside regions high regions low regions fluid levels visual indicia 86 to conveniently adjust thedamper 20 from outside thehousing wall 48. From this information, the technician can adjust thedamper 20 to a position where the first andsecond fluid levels predetermined regions indicia 86 as “good zones” having a green color to provide desired air quality. - Pursuant to still another feature of the invention a shut-off
supply switch 98 is communicated to sensing probes 80, 82 via tubing T1 and T2 to receive measurements therefrom. Theswitch 98 compares the pressure differential between the sensing probes 80, 82 with a predetermined pressure differential range (i.e. good zones) as calibrated by a technician for the specific burner and heater configuration. When the pressure differential is outside of the predetermined pressure differential range (good zones), theswitch 98 sends a signal to a flame relay 97 that sends a signal to close thevalve 87, which interrupts gas flow to theburner 18. Theswitch 98 andvalve 87 can be connected via a connecting means that can be an electrical, mechanical, or pneumatic conduit sufficient to send a signal from theswitch 98 and relay 97 tovalve 87. The connecting means is preferably conventional electrical wires W that receive an electrical signal. Thevalve 87 has an actuating mechanism that can be mechanical, electrical, or pneumatic to close and open the valve in response to a signal from the shut-off switch 98 to stop gas from reaching theburner 18 and can be a conventional solenoid valve. The invention also envisions that more than onevalve 87 can be used in practice of this invention. Thesupply line 88 is in communication with a source of gas and can be a conventional pipe for gas having conventional dimensions such as diameters of one inch (1″), one and a quarter inches (1¼′), etc. During operation of the direct fired heater, if the pressure differential between theprobes switch 98 through therelay 95 closes thevalve 87 to prevent the heater from operating under potentially dangerous conditions, i.e. the combustion byproducts could possibly be outside the ANSI standards. - This invention envisions a direct fired heater having one or more of the above features to facilitate and improve set-up of the heater for operation to heat a space.
- It is to be understood that the invention has been described with respect to certain specific embodiments thereof for purposes of illustration and not limitation. The present invention envisions that modifications, changes, and the like can be made therein without departing from the spirit and scope of the invention as set forth in the following claims.
Claims (19)
1. A direct fired heater comprising a housing forming an airflow passage and said airflow passage having an inlet and an outlet, an air moving device to flow air from said inlet to said outlet, a gas fired burner operatively associated with the housing, a pivotal airflow damper disposed in said housing relative to said gas fired burner to control the air flow rate through said burner, and an adjusting device to adjust said damper from outside said airflow passage.
2. The direct fired heater in claim 1 wherein said pivotal damper is adjacent to said gas fired burner in said airflow passage.
3. The direct fired heater in claim 1 wherein said pivotal damper pivots about an axis transverse relative to the longitudinal axis of said airflow passage.
4. The direct fired heater in claim 1 wherein said housing has a mixing chamber downstream from said burner for mixing partially combusted air from said burner and uncombusted air that passes through said damper to provide tempered air.
5. The direct fired heater in claim 1 wherein said pivotal damper has a pivotal shaft having an end portion residing outside of said airflow passage.
6. The direct fired heater in claim 5 wherein said adjusting device comprises an adjustable arm on said end portion to rotate said shaft and by which the damper is pivoted, and a locking means to maintain the adjusted position of said adjustable arm.
7. A direct fired heater comprising a housing forming an airflow passage and said airflow passage having an inlet and an outlet, an air moving device to flow air from said inlet to said outlet, a gas fired burner disposed in said housing, an airflow damper disposed in said housing relative to said gas fired burner to control the air flow rate through said burner, an upstream sensing probe disposed in said airflow passage upstream of said burner and said damper, a downstream sensing probe disposed in said airflow passage downstream of said burner and said damper, a pressure differential measuring instrument disposed outside of said airflow passage in communication with said upstream sensing probe and said downstream sensing probe, and an adjusting device to adjust said damper in response to said pressure differential measuring instrument.
8. The direct fired heater in claim 7 wherein said upstream sensing probe is a static tube or pitot tube.
9. The direct fired heater in claim 7 wherein said downstream sensing probe is a static tube or pitot tube.
10. The direct fired heater in claim 7 wherein said pressure differential measuring instrument is a fluid containing differential manometer comprising a U shaped conduit having a first tubular arm in communication with said downstream sensing probe, a second tubular arm in communication with said upstream sensing probe, a first fluid level in said first arm, and a second fluid level in said second arm.
11. The direct fired heater in claim 10 further comprising a visual indicia disposed outside of said airflow passage for viewing in conjunction with said first fluid level and said second fluid level of said differential manometer so that said first and second fluid levels can be adjusted during operational set up of said direct fired heater.
12. The direct fired heater in claim 7 wherein said damper pivots about an axis transverse relative to the longitudinal axis of said airflow passage.
13. The direct fired heater in claim 12 wherein said damper has a rotatable shaft having an end portion residing outside of said airflow passage.
14. The direct fired heater in claim 13 wherein said adjusting device said damper comprises an adjustable arm on said end portion to rotate said shaft and by which the damper is rotated; and a locking means to maintain the adjusted position of said adjustable arm.
15. The direct fired heater in claim 7 wherein said housing has a mixing chamber downstream from said burner and damper for mixing partially combusted air from said burner and uncombusted air that passes through said damper to provide tempered air.
16. The direct fired heater in claim 7 further comprising a supply line for supplying gas to said gas fired burner and having a valve to control the gas supply to said gas fired burner, and a shut-off switch in communication with said upstream sensing probe and said downstream sensing probe wherein said switch controls said valve to interrupt gas flow to said burner when a pressure differential between said upstream and downstream sensing probe is out of a predetermined pressure differential range.
17. A direct fired heater comprising a housing forming an airflow passage and said airflow passage having an inlet and outlet, an airflow passage disposed in said housing and having an inlet and an outlet, an air moving device to flow air from said inlet to said outlet, a gas fired burner disposed in said housing, an airflow damper disposed in said housing relative to said gas fired burner to control the air flow rate through said burner, an upstream sensing tube disposed in said airflow passage upstream of said burner and damper, a downstream sensing tube disposed in said airflow passage downstream of said burner and damper, a fluid containing differential manometer comprising a U shaped conduit having a first tubular arm in communication with said downstream sensing tube, a second tubular arm in communication with said upstream sensing tube, a first fluid level in said first arm, and a second fluid level in said second arm, a visual indicia disposed outside said airflow passage for viewing in conjunction with said first fluid level and said second fluid level of said differential manometer, an adjusting device to adjust said damper in response to said differential manometer, a supply line for supplying gas to said gas fired burner and having a valve to control the gas supply to said gas fired burner, and a shut-off switch in communication with said upstream tube and said downstream tube wherein said switch controls said valve to interrupt gas flow to said burner when a pressure differential between said upstream and downstream sensing tubes is out of a predetermined pressure differential range.
18. Method for controlling a direct fired heater where air is drawn through a passage in a housing and a portion of the air is combusted by a burner comprising sensing pressure upstream and downstream from an airflow damper, and adjusting said damper from outside of said passage until the measured pressure differential upstream and downstream of said damper falls into a predetermined range.
19. The directed fired heater of claim 5 wherein said end portion resides between an interior wall of said housing defining said airflow passage and an exterior wall of said housing, said exterior wall having an access to said end portion.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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US11/373,836 US20060266348A1 (en) | 2005-03-11 | 2006-03-10 | Direct fired heater with improved set-up features |
Applications Claiming Priority (2)
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US66092005P | 2005-03-11 | 2005-03-11 | |
US11/373,836 US20060266348A1 (en) | 2005-03-11 | 2006-03-10 | Direct fired heater with improved set-up features |
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US20060266348A1 true US20060266348A1 (en) | 2006-11-30 |
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US11/373,836 Abandoned US20060266348A1 (en) | 2005-03-11 | 2006-03-10 | Direct fired heater with improved set-up features |
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US20080184991A1 (en) * | 2004-03-25 | 2008-08-07 | Supplier Support International Inc. | Heated replacement air system for commercial applications |
US20090241943A1 (en) * | 2008-03-27 | 2009-10-01 | Schwank Ltd. | Pitot tube pressure sensor for radiant tube heater |
US20100294257A1 (en) * | 2009-05-15 | 2010-11-25 | Robert Thayer | Direct-fired heating system |
US20140197243A1 (en) * | 2013-01-15 | 2014-07-17 | Mestek, Inc. | Hydronic air heater |
US20140261370A1 (en) * | 2013-03-15 | 2014-09-18 | Mitek Holdings, Inc. | Dual bypass direct fired heating system with pressure control |
US20180087775A1 (en) * | 2016-09-28 | 2018-03-29 | Regal Beloit America, Inc. | Motor controller for blower in gas-burning appliance and method of use |
CN111542211A (en) * | 2020-07-09 | 2020-08-14 | 广东电网有限责任公司东莞供电局 | Power communication equipment box |
US10774838B2 (en) * | 2018-04-26 | 2020-09-15 | Regal Beloit America, Inc. | Motor controller for electric blower motors |
US10845064B2 (en) * | 2017-02-15 | 2020-11-24 | Johnson Controls Technology Company | Heating, ventilation, and air conditioning control system |
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Legal Events
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AS | Assignment |
Owner name: ABSOLUTAIRE, INC., MICHIGAN Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:JAUCH, JR., ROBERT T;OWEN, BRUCE;REEL/FRAME:017902/0407 Effective date: 20060531 |
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STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |