An induced draft, fuel-fired furnace having a heat exchanger with an inlet and an outlet includes a vent having an inlet, a burner, and a vented vestibule in fluid communication with the vent. A blower has an inlet in fluid communication with the heat exchanger outlet, and an outlet disposed at the inlet of the vent. The blower outlet has a cross-sectional area smaller than the vent inlet. The vent inlet and blower outlet define a vent inlet opening. A drafthood formed with an inlet is disposed in the vestibule and forms a plenum in fluid communication with the vent inlet opening. A source of combustion products is disposed in the furnace such that combustion products produced thereby are in fluid communication with the drafthood inlet and vent inlet opening. The source of combustion products includes either a standing pilot or electronic ignitor for igniting fuel operably discharged from the burner.
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27. An induced draft, fuel-fired furnace, comprising:
a heat exchanger having an inlet and an outlet; a vent including an inlet and a venturi section; a burner; ignition means for igniting fuel operatively discharged from said burner; a blower having an inlet in fluid communication with said heat exchanger outlet and an outlet in fluid communication with said vent inlet; and drafthood means separating said ignition means from said vent, said drafthood means having a plurality of openings to allow fluid communication between said ignition means and said venturi section.
12. The induced draft, fuel-fired furnace comprising:
a heat exchanger having an inlet and an outlet; a vent including an inlet and a venturi section; a burner; a vented vestibule in fluid communication with said vent; a blower having an inlet in fluid communication with said heat exchanger outlet and an outlet in fluid communication with said vent inlet; and a standing pilot disposed in said furnace such that combustion products provided thereby are in fluid communication with said venturi section, said standing pilot adapted to ignite fuel operably discharged from said burner.
34. An induced draft, fuel-fired furnace comprising:
a heat exchanger having an inlet and an outlet; a vent including an inlet and a venturi section; a burner; a blower having an inlet in fluid communication with said heat exchanger outlet and an outlet in fluid communication with said vent inlet; and a drafthood in fluid communication with said vent, said drafthood disposed in a vestibule of said furnace and forming a plenum in fluid communication with said vent inlet opening, said drafthood including an undersurface disposed adjacent said blower outlet and extending immediately adjacent to a panel of the furnace.
15. An induced draft, fuel-fired furnace, comprising:
a heat exchanger having an inlet and an outlet; a vent having an inlet; means for providing an area of lower pressure, said providing means defined at least in part by said vent; a vented vestibule; a burner disposed within said vestibule and in fluid communication with said heat exchanger inlet and said area of lower pressure; an induced draft blower having an inlet disposed in fluid communication with said heat exchanger outlet and an outlet disposed in fluid communication with the inlet of said vent; and means for igniting fuel operably discharged from said burner.
1. An induced draft, fuel-fired furnace having a heat exchanger with an inlet and an outlet, said furnace comprising:
a vent having an inlet; a burner; a vented vestibule in fluid communication with said vent; a blower having an inlet in fluid communication with the heat exchanger outlet, and an outlet disposed at the inlet of said vent, said blower outlet having a cross-sectional area smaller than said vent inlet, said vent inlet and blower outlet defining a vent inlet opening; and a standing pilot disposed in said furnace such that combustion products produced thereby are in fluid communication with said vent inlet opening, said standing pilot adapted to ignite fuel operably discharged from said burner.
53. An induced draft, fuel-fired furnace, comprising:
a vent having an inlet; a vented vestibule disposed in fluid communication with said vent, said vestibule comprising a plurality of panels; a blower having an inlet in fluid communication with said vestibule, and an outlet disposed at the inlet of said vent; a drafthood disposed in said vestibule, said drafthood forming a plenum in fluid communication with said vent, said drafthood in fluid communication with an aperture formed in one of said vented vestibule panels, said drafthood including an undersurface formed with an inlet; a burner disposed in said furnace and in fluid communication with said drafthood inlet; and igniting means for igniting fuel operably discharged from said burner.
47. An induced draft, fuel-fired furnace comprising:
a heat exchanger having an inlet and an outlet; a vent having an inlet; low pressure means for providing an area of lower pressure, said low pressure means defined at least in part by said vent; a burner disposed within a vestibule and in fluid communication with said heat exchanger inlet and said area of lower pressure; an induced draft blower having an inlet disposed in fluid communication with said heat exchanger outlet and an outlet disposed in fluid communication with the inlet of said vent; and a drafthood in fluid communication with said vent, said drafthood including an undersurface disposed adjacent said blower outlet and extending immediately adjacent to a panel of the vestibule.
24. An induced draft, fuel-fired furnace, comprising:
a vent having an inlet; a vented vestibule disposed in fluid communication with said vent, said vestibule comprising a plurality of panels; a blower having an inlet in fluid communication with the heat exchanger outlet said vestibule, and an outlet disposed at the inlet of said vent; a drafthood disposed in said vestibule, said drafthood forming a plenum in fluid communication with said vent and including an inlet , said drafthood in fluid communication with an aperture formed in one of said vented vestibule panels, said drafthood including an undersurface formed with an inlet, and a blocked vented vent detecting means adapted to detect a blocked exhaust gas flow condition in said vent; a burner disposed in said furnace and in fluid communication with said drafthood inlet; and means for igniting fuel operably discharged from said burner.
40. An induced draft, fuel-fired furnace, comprising:
a heat exchanger having an inlet and an outlet; a vent having an inlet; low pressure means for providing an area of lower pressure, said low pressure means defined at least in part by said vent; a burner disposed within a vestibule and in fluid communication with said heat exchanger inlet and said area of lower pressure; ignition means for igniting fuel operatively discharged from said burner, said means disposed in said vestibule; an induced draft blower having an inlet disposed in fluid communication with said heat exchanger outlet and an outlet disposed in fluid communication with the inlet of said vent; and drafthood means disposed in said vestibule and separating said ignition means from said vent, said drafthood means having a plurality of openings to allow fluid communication between said ignition means and said low pressure means.
64. An induced draft, fuel-fired furnace, comprising:
a heat exchanger having an inlet and an outlet; a flue including an inlet and a venturi section; a burner; igniting means for igniting fuel operatively discharged from said burner, said igniting means producing combustion gases; a blower having an inlet in fluid communication with said heat exchanger outlet and an outlet in fluid communication with said flue inlet, said blower having an operational mode and a non-operational mode; a vent adjacent said igniting means, said vent providing a source of ventilation air; and drafthood means positioned within said furnace and including a plurality of apertures to allow communication of said ventilation air from said vent to said flue and to create an updraft which draws said igniting means combustion gases from said igniting means through said drafthood apertures, into said venturi section, and to the outside environment through said flue during said non-operational mode of said blower.
58. An induced draft, fuel-fired furnace, comprising:
a vent having an inlet; a vented vestibule disposed in fluid communication with said vent, said vestibule comprising a plurality of panels; a blower having an inlet in fluid communication with said vestibule, and an outlet disposed at the inlet of said vent; a drafthood disposed in said vestibule, said drafthood forming a plenum in fluid communication with said vent, said drafthood in fluid communication with an aperture formed in one of said vestibule panels, said drafthood including an undersurface formed with an inlet; a burner disposed in said furnace and in fluid communication with said drafthood inlet; igniting means for igniting fuel operatively discharged from said burner; and blocked vent detecting means adapted to detect a blocked exhaust gas flow condition in said vent, said blocked vent detecting means including a temperature sensing means adapted to sense hot exhaust gases exhausted into said drafthood when a blocked exhaust gas flow condition exists in said vent.
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B6 86 and vents 88 allowing air flow from the ambient environment into vestibule 16. In the embodiment shown, front panel 26 is formed from two pieces of sheet metal providing respective removable covers for air inlet plenum 12 and vestibule 16. However, front panel 26 may be formed from a single piece of sheet metal providing a removable vertical panel adjacent air inlet plenum 12 and vestibule 16.
Vestibule 16 generally includes therein a burner assembly 42, induced draft blower 40 and drafthood 46. Burner assembly 42 includes a gas valve 48, burners 38, standing pilot 50 and housing 52. Gas valve 48 is of conventional design and operably supplies fuel, e.g., natural or LP gas, to the burners 38 and standing pilot 50. Burners 38, shown schematically in FIG. 3, are in-shot burners fixed within housing 52 having flame producing ends 54, e.g., such as an orificed jet, which respectively extend toward the inlet ends of the clam shell type heat exchangers 36. Burners 38, however, can be formed with other known constructions producing products of combustion which are circulated through heat exchanger 28. For example, U.S. Pat. No. 4,616,994 to Tomlinson, which is assigned to the assignee of the present invention, discloses a gas burner including means for reducing nitrous oxide emissions which may be used with the present invention.
In-shot burners 38 are affixed within housing 52 which in turn is affixed to the vertical wall 20. Housing 52 includes two upper horizontal surfaces 56 and 57 (FIG. 2) which are vertically offset and define an opening 58 allowing combustion gas produced by standing pilot 50 to flow therethrough via natural draft during idle conditions.
Induced draft blower 40 is fixed to vertical wall 20 and includes an inlet 60 in fluid communication with the outlets of clam shell heat exchangers 36. Induced draft blower 40 also includes a housing 62 with an outlet end 64 disposed at the upper end thereof. Disposed within housing 62 is an impeller 66 which is rotatably driven by a motor 68. Outlet end 64 is disposed immediately adjacent to the inlet end 70 of a flue or vent 72 fixed to top member 73. In the embodiment shown, inlet end 70 of flue 72 has a circular cross section with a diameter from 3 to 5 inches, and outlet end 64 of induced draft blower 44 has a circular cross section with a diameter of about 3 inches.
Because the cross-sectional area of the outlet end 64 of induced draft blower 40 is less than the cross-sectional area of the inlet end 70 of flue 72, an area of lower pressure 74 is formed in the space between the periphery of the outlet end 64 and inlet end 70. In the embodiment shown, lower pressure area 74 is defined as a vent inlet opening or venturi section having a generally annular shape. Lower pressure area 74 allows a natural draft within vestibule 16 when induced draft blower 40 is not operating. This fluid flow path is illustrated by the directional arrows indicated generally as 75. Thus, by providing an outlet 64 having a cross-sectional area less than the inlet end 70 of flue 72, the combustion products produced by the standing pilot 50 may be exhausted into the flue 72 and out into the ambient environment.
Although outlet 64 of induced draft blower 44, and inlet end 70 of flue 72 are shown with a generally circular cross-section, it is possible and considered within the scope of this invention to use an outlet 64 and inlet end 20 of different cross-sectional shapes.
A drafthood 46 is disposed within vestibule 16 at the upper end thereof (FIGS. 2, 3 and 4). Drafthood 46 includes an under surface 78 with a first opening 79 disposed around and closely adjacent outlet end 64 of induced draft blower 44, and two side members 80 forming a plenum when front panel 26 is in place (FIG. 1). A flange 83 having holes 85 formed therein allows attachment of drafthood 46 to the underside of upper surface 73.
Front panel 26 is formed with an aperture 86 disposed adjacent drafthood 46. Aperture 86 allows ambient air to enter the drafthood 46 and flue 72 and mix with and dilute the exhaust gases therein. Aperture 86 may be a single opening (as shown) or multiple openings (not shown), and the aperture(s) may be louvered.
Formed in the under surface 78 of drafthood 46 is at least one opening 82 (shown schematically in the drawings) allowing combustion gas produced by standing pilot 50 to flow therethrough and into flue 72. In the embodiment shown in FIGS. 2 and 3, two openings 82 are provided in undersurface 78 for allowing natural or induced draft through the vestibule 16. In an alternative embodiment shown in FIG. 4, five openings 82 are provided in undersurface 78 for allowing draft through the vestibule 16. Thus, it is apparent that the exact number of openings 82 formed in undersurface 82 is not critical so long as the combustion products from the standing pilot 50 are allowed to adequately flow therethrough into the drafthood 46.
One of the side members 80 is formed with a second opening 81 adapted to receive a blocked flue sensor means 84 (FIGS. 2 and 3) for detecting a blocked exhaust gas flow condition within flue 72. Sensor means 84 is connected to and operably controls gas valve 48 to prevent fuel flow through gas valve 48 when a blocked vent condition exists, thereby effectively stopping the operation of furnace 10. In the embodiment shown, blocked flue sensor means 84 is a temperature sensor for detecting when hot exhaust gas backflows from the vent into drafthood 46 from vent 72 because of a blocked vent condition. In an alternate embodiment (not shown), it may be possible to limit the size and configuration of openings 82 and aperture 86 and use a pressure sensing means disposed within one of the side members 80 to detect a blocked flue condition.
FIG. 5 shows another embodiment of the present invention utilizing an electronic ignition 51 discharged from burners. While electronic ignition 51 does not produce products of combustion during idle conditions of burners 38, it may nonetheless be desirable to use the drafthood of the present invention to detect, e.g., a blocked vent condition which might occur. The drafthood is in fluid communication with the vent inlet opening and dilution air opening, and includes an inlet trace or residual combustion products within vented vestibule 16 which may be produced by burners 38.
During an idle condition, a natural draft condition exists in vestibule 16 allowing products of combustion from standing pilot 50 to draft upwards through vestibule 16 and drafthood 46 into flue 72 and the ambient environment. Vents 88 formed in front panel 26 provide oxygen for combustion of fuel exhausted by burners 38 and standing pilot 50, and allow a draft to occur through vestibule 16 such as indicated by directional arrows 75. As combustion products flow upwardly though vestibule 16 and drafthood 46, dilution air flows inwardly from the ambient environment through aperture 86 into drafthood 46 and mixes with and thereby dilutes the standing pilot combustion products. Because induced draft blower 40 is not operating, an area of lower pressure forming a venturi 74 does not exist between the peripheries of outlet 64 and inlet end 70. That is, the area of the induced draft inlet opening between outlet 64 and inlet 70 has a pressure about the same as that existing within vestibule 16, drafthood 46 and flue 72. The products of combustion produced by standing pilot 50 are therefore free to flow upwards via a natural draft through vestibule 16 and into flue 72. The products of combustion of standing pilot 50 are not circulated through heat exchanger 28 during periods of inactivity of burners 38, thereby inhibiting the propensity for causing internal corrosion of heat exchanger 28 and unsafe pilot venting as described above.
During operation, an externally located thermostat (not shown), sends a signal initiating the production of heat from fuel-fired furnace 10. Fuel exhausted from in-shot burners 38 is ignited and drawn through heat exchanger 28 by induced draft blower 40 and exhausted upwardly through flue 72. The exhaust gas flows from outlet 64 of induced draft blower 40 and through inlet end 70 of flue 72, and an area of low pressure forming a venturi section 74 occurs between outlet 64 and inlet 70. Because the pressure existing within venturi section 74 is less than the pressure existing within vestibule 16, vestibule 16 is vented to flue 72 while induced draft blower 40 is operating.
While this invention has been described as having a preferred design, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.
Tomlinson, Ronald S., McKinney, Steven W.
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| Executed on | Assignor | Assignee | Conveyance | Frame | Reel | Doc |
| Oct 03 1997 | International Comfort Products Corporation (USA) | (assignment on the face of the patent) | / | |||
| Oct 31 2003 | International Comfort Products Corporation | INTERNATIONAL COMFORT PRODUCTS LLC | CHANGE OF LEGAL ENTITY | 035595 | /0666 | |
| Nov 30 2012 | INTERNATIONAL COMFORT PRODUCTS LLC | Carrier Corporation | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 035572 | /0364 |
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