This application is directed, in general, to heating, ventilation and air conditioning (HVAC) systems and, more specifically, to a high efficiency furnace having a finger air baffle.
A high-efficiency furnace typically employs several heat exchangers to warm an air stream passing through the furnace. A high-efficiency furnace is one where approximately 90% of the energy put into the furnace is converted into heat for the purposes of heating the targeted space. These high-efficiency furnaces include “clamshell” or individual panel halves formed by stamping mirror images of the combustion chambers into corresponding metal sheets and coupling them together. Often high-efficiency furnaces comprise a primary heating chamber that includes the clamshell heat exchangers and a secondary heat exchanger/condenser. The air passes through the secondary heat exchanger/condenser from a blower or fan and then passes through the primary heat exchanger. High-efficiency furnaces are also characterized by high operating temperatures. However, cracking problems in the clamshell heat exchanger panels can occur when the temperatures within the heat exchanger consistently exceed about 950 degrees. When such cracks appear, their occurrence is considered a failure of the system.
One aspect of this disclosure provides a finger baffle for a heating furnace. This embodiment comprises an elongated support plate having a length, and at least one finger baffle extending outwardly and in a vertically oriented direction from the elongated support plate. The at least one finger baffle has a width that extends along the length of the elongated support plate.
Another aspect provides a high-efficiency gas furnace. In one embodiment the furnace comprises a housing, a primary heating zone located within the housing that includes spaced apart primary heating chambers, wherein each of the primary heating chambers has a pre-determined hot spot associated therewith and located adjacent an outlet end of each of the primary heating chambers. This embodiment further comprises a secondary heat exchanger and condenser zone located downstream of an air flow path from the primary heating zone and the finger baffle as described above. A blower is located within the housing proximate and downstream of the air flow path from the secondary heat exchanger and condenser zone.
A method of fabricating a finger baffle for a heating furnace is also provided. One method embodiment comprises forming an elongated body having a length from sheet metal, forming spaced apart finger baffles from the elongated body, and bending the finger baffles such each of the finger baffles extend outwardly and in a vertically oriented direction from the elongated support plate, each of the finger baffles having a width that extends along a length of the elongated body.
In another aspect, a method of fabricating a high-efficiency gas furnace is provided. This method embodiment comprises providing a housing, placing a primary heating zone within the housing that includes spaced apart primary heating chambers, wherein each of the primary heating chambers has a pre-determined hot spot associated therewith and located adjacent an outlet end of each of the primary heating chambers. The method further comprises placing a secondary heat exchanger and condenser zone within the housing, located downstream of an air flow path from the primary heating zone, and attaching a finger baffle to a frame of the primary heating zone and adjacent the outlet end of the primary heating chambers. The finger baffle comprises an elongated support plate having a length and spaced apart finger baffles extending outwardly and in a vertically oriented direction from the elongated support plate, each of the finger baffles having a width that extends along the elongated support plate and a length that extends from the elongated support plate to the pre-determined hot spot. A blower is placed within the housing proximate and downstream of the air flow path from the secondary heat exchanger and condenser zone.
Reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:
Described herein are various embodiments of a vertically oriented finger baffle that may be employed in a high-efficiency furnace adjacent an outlet end of a heat exchange chamber panel. As used herein and in the claims, a vertical orientation includes those configurations where the individual finger baffles deviate from a true vertical orientation of 90 degrees with respect to a support plate of the finger baffle by about −45 degrees to about +15 degrees. The finger baffle is designed to be placed within a primary heating zone of a furnace and between heating chambers proximate an outlet end thereof, where it guides the air to a hot spot located proximate the outlet end of the heating chamber. The purpose of finger baffle, as provided herein, is to reduce the temperature at the hot spot associated with each heating chamber without detrimentally increasing cubic feet per minute (CFM) airflow of the furnace.
In present day furnaces, expensive material is used to construct heat exchangers due to the high operating temperatures. Due to the benefits associated with the finger air baffle as presented herein, manufactures can use lower cost EDDS materials, thereby reducing manufacturing costs while maintaining the operational life of the high-efficiency furnace. In certain embodiment, the finger baffle successfully reduces the temperature of the heating chamber to 937° F. The embodiments of the finger baffle as presented herein do not detrimentally increase or decrease the main blower performance, thus the CFM/watt remains the same as found in present conventional units. Additionally, it reduces the flue temperature, which increases the furnace's efficiency.
In general, the various embodiments of the finger baffle provides airflow to a hot spot by providing a surface of sufficient width along which airflow travels, thereby effectively guiding the airflow to the desired area on the heating chamber. Without being limited by any theory of operation, it is believed that the airflow guidance is based on the coanda effect, wherein the fluid airflow is attracted to the flat surface of the finger baffles. The guidance of the airflow causes the air to be directed more toward hot spots adjacent the finger baffles, thereby reducing the temperature of the heating chambers and keeping their operating temperature within design parameters, which prevents premature stress and cracking in the area of the hot spot. The lengths of the fingers of the baffle, the widths of the finger baffles, the material out of which the finger baffle is constructed, and the location and orientation of the finger baffle relative to the heat exchanger panels potentially affect the performance of the finger baffle.
Though the finger baffle as presented herein could be used in any furnace chamber, it provides particular benefits to high-efficiency furnaces where 90% of the fuel burned is converted directly into heat. The benefits arise from the fact that these high-efficiency furnaces reach higher operational temperatures, which causes the heating chambers to prematurely stress and crack at the above-mentioned hot spots. As stated above, the finger baffles help guide the airflow more directly to these hot spots, which reduces stress and premature cracking.
A burner assembly 140 contains a thermostatically-controlled solenoid valve 142, a manifold 144 leading from the valve 142 and across the burner assembly 150, one or more gas orifices (not shown) coupled to the manifold 144 and one or more burners (not shown) corresponding to and located proximate the gas orifices. The illustrated embodiment of the burner assembly 140 has a row of six burners. Alternative embodiments of the burner assembly 140 have more or fewer burners arranged in one or more rows. A flue 146 allows undesired gases (e.g., unburned fuel) to be vented from the burner assembly 140. In an assembled configuration, the burner assembly 140 is located proximate the heat exchanger assembly 120 such that the burners thereof at least approximately align with the inlets 132.
A draft inducer assembly 150 contains a manifold 152, a draft inducing exhaust fan 154 having an inlet coupled to the manifold 152 and a flue 156 coupled to an outlet of the exhaust fan 154. In an assembled configuration, the draft inducer assembly 150 is located proximate the heat exchanger assembly 120, such that the manifold 152 thereof at least approximately aligns with the outlets 134 and the flue 156 at least approximately aligns with the flue 146 of the burner assembly 140.
A blower 160 is suspended from the shelf 110 such that an outlet (not referenced) thereof approximately aligns with the opening 115. An electronic controller 170 is located proximate the blower 160 and, in the illustrated embodiment, controls the blower, the valve 142 and the exhaust fan 154 to cause the furnace to provide heat. A cover 180 may be placed over the front opening 105 of the housing 100.
In the illustrated embodiment, the controller 170 turns on the exhaust fan to initiate a draft in the heat exchangers (including the primary heating zone 130) and purge potentially harmful unburned gases or gaseous combustion products. Then the controller 170 opens the valve 142 to admit gas to the manifold 144 and the one or more gas orifices, whereupon the gas begins to mix with air to form primary combustion air. Then the controller 170 activates an igniter (not shown in
Though seven finger baffles 410 are shown, it should be understood that other embodiments may provide fewer (at least one) or more than what is shown. The number of individual finger baffles 410 that will be present can depend on the number of heating chambers 130a present in the furnace in which the finger baffle device 400 will be used. For example, in one aspect, the finger baffle device 400 may be designed such that an individual finger baffle 410 is be placed adjacent each hot spot of each heating chamber 130a, however, an individual finger baffle 410 need not be associated with each heating chamber 130a, although in a preferred embodiment, such will be the case. The finger baffles 410 are located along the edge of the elongated support plate 405 that is closest to the inlet end 212 (
In one aspect of this disclosure, the individual finger baffles 410 may be individually attached to the elongated support plate 405. However, in another embodiment, they may be integrally formed from the elongated support plate 405, as shown in
With the present disclosure, it has been found that these ranges provide improved results over angles less than 70 degrees as taken from the reference line 420. Tests were conducted where the individual finger baffles were positioned at 70 degrees, 84 degrees, and 90 degrees adjacent each heating chamber 130a to determine what affect they would have on the maximum operating temperature of the furnace. These results were compared with an instance where no baffle was used. The results are illustrated in Table 1, as follows:
As seen from the foregoing data, the presence of the finger baffle made a significant improvement in the operating temperature of the furnace, with the 90 degree position showing the best improvement. Though there is a slight variation in the results of 70 degrees and 84 degrees, it should be noted that when angle positions of less than 45 degrees were tested, the maximum operating temperature of the furnace increased above the temperatures noted for the finger baffle configurations.
In another aspect, the finger baffle 400 further includes an angled connecting plate 425 integrally formed with and extending downwardly from the elongated support plate 405. In one embodiment, the connecting plate 425 extends downwardly from said elongated support plate at a 90 degree angle and extends along the length of the elongated support plate 405. When present, the connecting plate 425 can be used to connect to the frame of the primary heating zone 130 (
With reference to
In another aspect, the method of forming the elongated body 405 may include cutting enough sheet material such that an angled connecting plate 425 can be formed by bending the elongated body 405 in a downward direction from the elongated support plate 405, and preferably at a 90 degree angle from the elongated body 405.
In another embodiment, there is provided a method of fabricating a high efficiency gas furnace 100. This embodiment comprises providing a housing 102, placing a primary heating zone 130 within the housing 100 that includes spaced apart heating chambers 130a, wherein each of the heating chambers 130a has a pre-determined hot spot 215 associated therewith and located adjacent an outlet end 210 of each of the heating chambers 130a. The method further comprises placing a secondary heat exchanger and condenser zone 135 within the housing 102, located downstream of an air flow path from the primary heating zone 130. The finger baffle 400 as described above is then positioned with the primary heating zone 130 and adjacent the outlet end 210 of the primary heating zone 130. A blower 160 is also positioned within the housing 102 proximate and downstream of the airflow path 605 from the secondary heat exchanger and condenser zone 135.
Those skilled in the art to which this application relates will appreciate that other and further additions, deletions, substitutions and modifications may be made to the described embodiments.
This application is a continuation of U.S. patent application Ser. No. 15/423,103 filed on Feb. 2, 2017. U.S. patent application Ser. No. 15/423,103 is a continuation of U.S. patent application Ser. No. 13/705,861 filed on Dec. 5, 2012, which is now U.S. Pat. No. 9,593,865 entitled “Finger Air Baffle For High Efficiency Furnace” and incorporated herein by reference in its entirety.
Number | Name | Date | Kind |
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3213324 | McAdam | Oct 1965 | A |
3694703 | Wilens | Sep 1972 | A |
D275749 | McCarthy | Oct 1984 | S |
4588028 | Marshall | May 1986 | A |
4970579 | Arldt | Nov 1990 | A |
5311395 | McGaha | May 1994 | A |
5311928 | Marton | May 1994 | A |
6249437 | Ferranti | Jun 2001 | B1 |
6851469 | Sears | Feb 2005 | B2 |
7746650 | Hellinger | Jun 2010 | B2 |
20190242568 | Luiten | Aug 2019 | A1 |
Number | Date | Country | |
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20190368727 A1 | Dec 2019 | US |
Number | Date | Country | |
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Parent | 15423103 | Feb 2017 | US |
Child | 16544037 | US | |
Parent | 13705861 | Dec 2012 | US |
Child | 15423103 | US |