GB2313439A

GB2313439A - Convector box gas fires

Info

Publication number: GB2313439A
Application number: GB9710536A
Authority: GB
Inventors: Josef Hacohen
Original assignee: COMBUSTION PRODUCTS DEVELOPMEN
Current assignee: COMBUSTION PRODUCTS DEVELOPMEN
Priority date: 1996-05-22
Filing date: 1997-05-22
Publication date: 1997-11-26
Also published as: GB9610736D0; GB9710536D0

Abstract

A convector box gas fire includes a housing (18, 19, 20) and a burner (10) located within a part of the housing which is bounded by an internal wall (21) such that an airflow passage is provided within the housing rearwardly of said internal wall (21). Combustion products from the burner pass upwardly in front of the internal wall (21) in heat exchange relationship with air flowing upwardly within said airflow passage. Scoops (24) are provided at the two bottom corners of the housing to direct air into said airflow passage.

Description

CONVECTOR BOX GAS FIRES Field of the Invention This invention relates to convector box gas fires, i.e. to gas fires which include an arrangement whereby air from the room or other space being heated is drawn in under the fire, passes upwardly to the rear of the fire in heat exchange relationship with the hot combustion products which are passing up a chimney or other discharge outlet, and then issues into the room or other space to be heated above the fire.

One example of a convector box gas fire is shown in Figures 10 and 11 of the drawings of British Patent Specification No. 2 185 100.

A disadvantage of previous designs of convector box gas fires is that they are extremely inefficient. Relatively little air is caused to pass through the passageways which extend to the rear of the fire and, in some circumstances, the amount of thermal energy being discharged into the room or other space to be heated is not sufficient to counteract the cooling effect of the cold air being drawn into the room to replace the air passing up the chimney.

It is accordingly an object of the present invention to provide an improved form of convector box fire and, in particular, to provide a convector box gas fire which operates more efficiently than existing gas fires.

Summarv of the Invention According to the present invention there is provided a convector box gas fire which includes a housing and a burner contained within the housing, the burner being located within a part of the housing which is bounded by an internal wall such that an airflow passage is provided within the housing rearwardly of said internal wall, the arrangement being such that combustion products from the burner pass upwardly in front of the internal wall in heat exchange relationship with air flowing upwardly within said airflow passage, 'scoops' being provided at the base of the housing to direct air into said airflow passage.

Two 'scoops' are preferably provided, one at each bottom front corner of the housing so that, as a convection flow of air is generated by operation of the burner, a significant portion of said convection flow will enter the 'scoops' and will flow beneath the burner to the base of said airflow passage.

The internal wall which defines the front of the airflow passage preferably includes a central planar portion which extends parallel to the plane of the front of the fire and wing portions at either end of said central planar portion, which wing portions extend forwardly from and are inclined relative to the central planar portion.

The rear wall of the housing preferably extends parallel to the central planar portion of said internal wall and is spaced therefrom to afford the space for said airflow passage.

The internal wall is preferably provided with a plurality of spaced fins which extend towards the rear wall of the housing and serve to promote heat exchange between the hot combustion products flowing upwardly in front of the internal wall and the air flowing upwardly to the rear of the internal wall.

The 'scoops' for promoting the entry of air into said airflow passage are preferably located so that they extend forwardly to positions in front of the forward edge of the burner so that, as convection currents are generated as a result of operation of the burner, a proportion of the air drawn towards the fire along the floor of the room or other space to be heated will enter said 'scoops'.

The cross-sectional area of the airflow passage to the rear of said internal wall will preferably be significantly greater than the combined cross-sectional areas of the 'scoops'. No restriction to the flow of air through the airflow passage will accordingly be provided and the fins extending across said airflow passage will preferably be in the form of vertical strips of minimal thickness so as to provide minimal restriction to said airflow.

The burner preferably comprises a layer of flame trap material through which the gas/air mixture is caused to flow upwardly and a cover plate on top of the layer of flame trap material. The cover plate will be formed with a series of appropriately positioned spaced apertures so that a plurality of discrete areas of combustion will be formed just above the cover plate.

In plan, the burner is preferably of trapezoidal configuration, with the front and rear edges of the burner parallel to one either and with the side edges of the burner inwardly and rearwardly inclined at equal inclinations to the front edge of the burner so as to provide a compact construction which, by being of greater width at the front, is more efficient than conventional burners which are of generally rectangular form in plan view.

The apertures in the cover plate through which the gas/air mixture passes upwardly prior to combustion may be arranged in two rows, with a first row located towards the front edge of the burner and a second row located towards the rear edge of the burner. There are preferably more apertures in the first row than in the second row.

Brief DescriDtion of the Drawings Figure 1 corresponds to Figure 10 of the drawings of Patent Specification No. 2185100, Figure 2 corresponds to Figure 11 of the drawings of Specification No. 2 185 100, Figure 3 is a plan view of the burner of a gas fire in accordance with the present invention, Figure 4 is a vertical sectional view of the rear part of the gas fire of Figure 3, Figure 5 is a sectional view along the line A - A of Figure 4, Figure 6 is an exploded plan view of the parts defining the airflow passage at the rear of the gas fire, and Figure 7 is a front view of an internal wall within the gas fire, which wall is one of the parts defining said airflow passage.

Description of the Preferred Embodiments Figures 1 and 2 show a known convector box gas fire which includes a heat exchanger 63. The heat exchanger 63 comprises a plurality of tubes 64 which are disposed in spaced array behind and above the fire so that the combustion gases 65 passing to the chimney or flue 66 can pass around the tubes 64. The lower ends of the tubes 64, which have insulation 70 disposed at the rear end thereof, are connected to a collector box 67 having an air inlet 68 adjacent its base so that cold air can be drawn therein from the room. The cold air passes up the tubes 64, where it receives heat from the combustion gases 65 and hot air passes out of the outlet 69 above and in front of the fire which comprises a grate 112, a burner box 113 and imitation logs 59, 60 and 62 disposed on top of a ceramic blanket 123.

The burner 10 shown in Figure 3 is constructed generally as described in Patent Application No. 9603040.8, to which reference should be made, and is of generally trapezoidal configuration in plan view having a front edge 11 which is longer than its rear edge 12. The burner includes an apertured cover plate 13 located immediately above a mesh or ceramic matrix 14. There is a first row 15 of six apertures adjacent the front edge of the cover plate 13 and a second row 16 of four apertures adjacent the rear edge of the cover plate 13. The apertures are for the flow of the gas/air mixture which is ignited above the cover plate 13, with such ignition being assisted by the provision of smaller apertures which connect the two rows 15 and 16 and which connect the first row 15 with the pilot assembly 17. Artificial logs or coals (not shown) are placed on top of the cover plate 13 and the combustion products exit from the housing of the fire through an outlet flue which extends for substantially the full width of the top of the housing, thereby creating an airflow as indicated by the arrows in Figure 5. Air enters the front of the housing over substantially the whole of the front of the housing.

The housing has a back wall 18 and side walls 19 and 20 with an interior wall 21 which includes a central planar portion 21a which extends parallel to the back wall 18 of the housing, and a pair of wing portions 21b and 21 c which are inclined outwardly and forwardly relative to the central portion 21a. A number of vertical channel section elements 22 are secured to the rear of the interior wall 21 and act as heat-transmitting fins extending towards the back wall 18 and the side walls 19 and 20 of the housing.

Cut-outs 23 are formed at the two bottom corners of the interior wall 21 and 'scoops' are provided for directing air from the front of the housing into the space behind the interior wall 21 through said cut-outs 23. The scoops are in the form of channels 24 which extend from front to back of the housing below the level of the cover plate 13.

Thus, as air is drawn towards the open front of the housing, as indicated by the arrows in Figure 5, a proportion of said flow of air will enter the channels and will pass through the cut-outs 23 into the space behind the interior wall 21.

The central portion 21 a of the interior wall 21 is welded to a deflector plate 25 which is positioned so as to create turbulent flow of the combustion products of the burner 10 and to provide an expansion space 26 which encourages or promotes air flow behind the central portion 21a of the interior wall.

The volume of air flowing behind the interior wall 21 (in heat exchange relationship with the combustion products in front of the wall 21) is thus increased, this air then being returned to the room in which the gas fire is located to provide enhanced convection heating. The degree of heat exchange is also improved by the arrangement of the present invention.

Claims

Claims:

1. A convector box gas fire which includes a housing and a burner contained within the housing, the burner being located within a part of the housing which is bounded by an internal wall such that an airflow passage is provided within the housing rearwardly of said internal wall, the arrangement being such that combustion products from the burner pass upwardly in front of the internal wall in heat exchange relationship with air flowing upwardly within said airflow passage, 'scoops' being provided at the base of the housing to direct air into said airflow passage.

2. A gas fire as claimed in Claim 1, in which two 'scoops' are provided, one at each bottom front corner of the housing so that, as a convection flow of air is generated by operation of the burner, a significant portion of said convection flow will enter the 'scoops' and will flow beneath the burner to the base of said airflow passage.

3. A gas fire as claimed in either of the preceding claims, in which the internal wall which defines the front of the airflow passage includes a central planar portion which extends parallel to the plane of the front of the fire and wing portions at either end of said central planar portion, which wing portions extend forwardly from and are inclined relative to the central planar portion.

4. A gas fire as claimed in Claim 3, in which the rear wall of the housing extends parallel to the central planar portion of said internal wall and is spaced therefrom to afford the space for said airflow passage, the internal wall being provided with a plurality of spaced fins which extend towards the rear wall of the housing and serve to promote heat exchange between the hot combustion products flowing upwardly in front of the internal wall and the air flowing upwardly to the rear of the internal wall.

5. A gas fire as claimed in any one of the preceding claims, in which the 'scoops' for promoting the entry of air into said airflow passage are so located that they extend forwardly to positions in front of the front edge of the burner so that, as convection currents are generated as a result of operation of the burner, a proportion of the air drawn towards the fire along the floor of the room or other space to be heated will enter said 'scoops'.

6. A gas fire as claimed in Claim 5 as appendant to Claim 4, in which the cross-sectional area of the airflow passage to the rear of said internal wall is significantly greater than the combined cross-sectional areas of the 'scoops'.

7. A gas fire as claimed in any one of the preceding claims, in which the burner comprises a layer of flame trap material through which the gas/air mixture is caused to flow upwardly and a cover plate on top of the layer of flame trap material, the cover plate being formed with a series of appropriately positioned spaced apertures so that a plurality of discrete areas of combustion will be formed just above the cover plate.

8. A gas fire as claimed in Claim 7, in which the burner is of trapezoidal configuration in plan, with the front and rear edges of the burner parallel to one another and with the side edges of the burner inwardly and rearwardly inclined at equal inclinations to the front edge of the burner.

9. A gas fire as claimed in Claim 8, in which the apertures in the cover plate through which the gas/air mixture passes upwardly prior to combustion are arranged in two rows, with a first row located towards the front edge of the burner and a second row located towards the rear edge of the burner.

10. A gas fire as claimed in Claim 9, in which there are more apertures in the first row than in the second row.

11. A gas fire as claimed in Claim 1 and substantially as hereinbefore described with reference to and as shown in Figures 3 to of the accompanying drawings.