A flue shield device

Abstract

A flue cap for a co-axial flue condensing boiler (1, figure 1) comprises a plate 31 having an orifice (52, figure 4) to receive an exhaust duct end 6 of a co-axial flue, and an apron 33 provided about a periphery of the plate and extending towards a wall (2, figure 1) of a building the boiler is disposed within in use. Ideally the flue cap includes a slot 37 to permit draining of rainwater from the cap. The flue cap may include nubs (60, figure 6) to space the plate from an air duct end 3 of the co-axial tube. The orifice is sized to provide an interference fit between the plate and the exhaust duct end. A co-axial flue boiler having a flue cap on a co-axial flue thereof is also claimed.

Description

Technical Field The technical field of this invention relates to condensing boilers, these are a particular type of boiler with specific and peculiar features and requirements, such as the provision of a tubular combustion gas discharge and combustion air supply duct and forced air circulation devices. Even more specifically the technical field of the invention relates to a tubular coaxial air inlet and exhaust gas duct for a condensing boiler and a method and means that prevents the induction of driven rain wind or other debris from being introduced into the boiler and effecting the proper operation of the said boiler. Preferably the invention may be the provision of a flue shielding device accessory for the inlet duct of a tubular co-axial flue heating boiler. Background and Summary As known in the prior art, a condensing boiler is a device in which heat is exchanged between hot gas formed by the combustion of air and a fuel and a working fluid to be heated (usually water). Therefore, a condensing boiler comprises amongst other aspects, a burner, which is provided to release and mix the supplied fuel gas with atmospheric air, at least one or more heat exchanger in which the hot gases are introduced to heat the working fluid (water) circulating in said heat exchangers. These components (burner and heat exchangers) are housed inside a normally sealed housing or casing, which has separate inlet opening duct for the fuel gas, combustion air, and water, and separate outlet duct for the by-products of combustion smoke and heated water and or steam and condensate. Preferably the tubular inlet air duct and tubular exhaust gas ducts are co-axial and the exhaust duct is of smaller diameter and located inside the inlet air duct. Due to the specific processes of operation of a condensing boiler the products of combustion are towered in temperature within a second heat exchanger nominally to a temperature below that of the condensing point of water, this improves overall energy efficiency and results in transformation of exhaust combustion steam into condensate. This condensate settles by gravity in the lower portion of the heat exchanger and must be drained. Condensing boilers are by necessity of a more complex design that a simple heating boiler and therefore may be more susceptible to damage or corrosion due to wind blown rain or dust debris etc entering into the heat exchangers or combustion area or electronics control systems. Preferably condensing heating boilers are fitted with at least a power driven fan or fans to draw atmospheric air into the boiler combustion process and or discharge exhaust gasses from the boiler utilising the tubular co-axial inlet and exhaust ducts respectively. An object of the present invention is therefore to provide an improvement to the distal end of a boiler tubular co-axial inlet duct and or an accessory device that can be fixed to the existing distal end of said boiler tubular co-axial exhaust duct to prevent rain and or other debris from being blown into the said boiler inlet duct opening. The present invention further consists of at least a first plate, said plate substantially perpendicular to the axis of a co-axial boiler duct and of a sufficient outer dimension and surface area to obscure from direct air flow a greater outer dimension and surface area than that of the existing tubular co-axial duct distal end, further said first plate is provided with a tubular sleeve or apron of substantially cylindrical portion, said sleeve or apron fixed substantially perpendicular to the periphery of said first plate wherein said sleeve or apron extends rearwards from said first plate periphery over at least above a portion of the distal edge of said tubular inlet duct distal end opening. According to another aspect of the present invention there is provided an assembly of a tubular co-axial duct accessory item and a gas appliance. The accessory item assembly includes a gas appliance and a co-axial duct accessory as mentioned above. The accessory item including a hole or sleeve within a first plate which can be a friction or slide fit over the exhaust tubular outlet and consists of at least a first plate, said plate substantially perpendicular to the axis of a co-axial boiler duct and of a sufficient outer dimension and surface area to cover a greater outer dimension and surface area than that of the existing tubular co-axial duct distal end, further said first plate is provided with a tubular sleeve or apron of substantially cylindrical portion, said sleeve or apron fixed substantially perpendicular to the periphery of said first plate wherein said sleeve or apron extends rearwards from said first plate periphery over at least above a portion of the distal edge of said tubular inlet duct distal end opening. Importantly the plate of the accessory item need not be of a particular shape, it may be circular or square, it could be ovoid or of a triangular shape or any other shape, importantly however the size and orientation of the plate should be sufficient to prevent direct or substantially direct impingement of wind, gusts, driven rain or other debris from being induced into the tubular co-axial inlet duct, again the angle or slope of the plate in relation to the ground need not be perpendicular or substantially perpendicular, however the front face or outer surface of the plate should be sufficiently angled to provide for shedding of rain or other debris away from the inlet of the tubular co-axial air inlet duct. Even further said sleeve or apron may not be of said cylindrical portion but of any shape or part shape with such orientation that at least a rearward projection of the apron from said front plate may abut at least above and or to sufficiently overlap the inlet duct edge or the distal end of said tubular co-axial inlet duct opening. Even more importantly towards the lower edge of the said plate a gap or drain slot may be advantageously situated such that rain or moisture may drain away from the inlet duct of the boiler. Conventual the co-axial tubular duct consisting the inlet and exhaust ducts of the condensing boiler are positioned substantially or preferably horizontal to and orthogonal to the force of gravity, however variations from this may be acceptable and specified by local or national regulations such as 2% or 4% or another gradient towards the appliance or away from the appliance towards the outside as required. Description of the Invention The present invention relates to a gas fired heating boiler of the sealed type, specifically of a seated type known as a condensing boiler wherein the inlet combustion air and the products of combustion are conveyed into and out of the sealed boiler housing in a co-axial inlet air and exhaust gas ducting. Specifically the present invention relates to such condensing boilers where the distal end of such coaxial inlet and exhaust gas duct may be positioned within an environment where the distal end openings of the said duct may be subject to the flow of wind, draft, turbulent airflow disturbances, rain, driven rain, airborne debris, leaves dust etc that may influence inlet air flow and exhaust flow and or debris etc may be introduced into the distal end opening of the inlet duct whereby resulting in degraded operation, corrosion and ioss of efficiency of the said condensing heating boiler. Importantly the design of the tubular co-axial inlet and exhaust duct, and most specifically the distal end of such ducts must take into consideration the inlet airflow and exhaust gas outflow ensuring wind rain or driven debris etc does not influence combustion efficiency or for example cause exhaust gas to recirculate or effect combustion or increase carbon monoxide formation due to poor air flow and the proper operation of a condensing boiier. Preferably the exhaust duct in found to be the inner tubular duct and the inlet to be the outer tubular duct, even more preferably the exhaust duct is found to be extended such that its distal end opening extends beyond the distal end of the inlet duct opening. The present invention even more specifically relates to a component part or an accessory which may be added to the distal end of an existing and inferior design of co-axial inlet and exhaust duct thereby preventing the induction by the inlet duct at the distal end openings of the said duct of wind, draft, turbulent airflow disturbances, rain, driven rain, airborne debris, leaves dust etc from affect the operation of the combustion process and or causing damage to the internal component parts of such a condensing boiler. The present invention will now be described with reference to the following drawings; fig 1 shows a highly stylised drawing of a standard condensing heating boiler of a coaxial flue design. fig 2 shows a highly stylised drawing of a condensing heating boiler of a co-axial flue design with the present invention located at the distal end of the co-axial inlet and exhaust duct. fig 3 shows an accessory invention from the front fig 4 shows an accessory invention from the rear fig 5 shows an accessory invention as viewed from the underneath fig 6 shows an accessory sectioned view from the side fig 7 and 8 show a three quarter perspective view of an accessory from the front and back respectively Description A condensing boiler, 1 may be located upon a wall or any other substantially vertical surface 2, a tubular coaxial boiler flue has an inlet duct end 3 and an exhaust duct end 6, combustion air 'A' is drawn in to the boiler by suction device (fan) 9 into a combustion chamber 12, where fuel gas from duct 15 is mixed with air from inlet 3 and burned to produce heating gases 'H' which heats a working fluid (water) flowing in primary heat exchanger 17 via pipe 18 (inlet) and 19 (outlet) said working fluid forming a circuit external to said condensing boiler wherein the now heated working fluid may pumped to suitable heat receptors, not shown, for use. Importantly to improve efficiency of such heating boilers a secondary or low temperature heat exchanger 22 optimally absorbs waste heat from gas W exhausted from the primary heat exchanger 17 to heat the returning cooled working fluid from the external heat receptors before being heated to high temperature in the said primary heat exchanger 17. Said low temperature heat exchanger thereby lowering the temperature of the combustion products and heating gases "W2" resulting in a condensate of mainly water being formed and falling to collection well 25 to be drained by duct 27 to a suitable disposal location not shown. When operating correctly and in conditions where there is no adverse flow of wind or any turbulent airflow or driven rain or debris around or into the distal end openings of the inlet and exhaust duct the boiler will operate correctly and efficiently as designed by the manufacturer. However, correct operation and efficiency of the said condensing boiler in fig 1 can be seriously and disastrously compromised by foreign material, dust, leaves, water and driven rain and or turbulent air flow and drafts which may disrupt the correct operation of the combustion device, gusts may even blow out the flame or cause inefficient combustion or the fuel gas, rain or debris may form corrosion within the ducts, block the drain 27, cause corrosion within the heat exchangers and or burner assembly and result in blockages of the condensation drain 27 or poor air flow etc. Figure 2 shows a first embodiment of the said invention where the distal end of the tubular coaxial inlet 35 and inlet duct 3 and tubular exhaust dust 6 is provided with and include a substantially vertical plate 31, said plate fixedly located about a periphery of said exhaust duct 6, but located and spaced apart from inlet duct 3, therefor providing a quiescent area "Q", between said plate 31 and wall 2, said plate 31 providing a blocking device or blocking component or shield to prevent wind, drafts, rain, dust, leaves, debris and or other foreign material from being blown into the tubular inlet duct 3, or induced into the tubular inlet duct 3, by suction device 9. The plate shield device may prevent such debris etc from being induced from at least a first set of directions 'X' further said plate 31 shows an attached sleeve or apron 33, said sleeve or apron substantially perpendicular and of substantially cylindrical or part cylindrical form thereby providing a blocking device or shield to prevent wind, rain, dust, debris or other foreign material from being blown into or induced into the inlet duct 3, from a further set of radial directions, for example "X2". Plate 31 may further comprises at least a first drain or slot 37, located at or towards the periphery of said plate 31 and before or within said sleeve or apron to allow rain water or other debris to drain away from the rear of the plate thereby preventing a build-up of material or rain water. Further there maybe provided a flue shielding accessory device Fig 3 to Fig 8 whereby an existing co-axial heating boiler inlet and exhaust duct may be retrospectively improved by the addition of the simple features as described above. Importantly the accessory device 50, consists at least of plate 31, said plate 31 is provided with a suitable orifice 52, said orifice is sized and located to enable the accessory device 50 to be slidably affixed, preferably by a friction and or sliding fit over and upon the coaxial exhaust duct 6 and stepped away from the inlet duct 3 further said plate 31 shows an attached sleeve or apron 33, said sleeve or apron substantially perpendicular and of substantially cylindrical or part cylindrical form thereby providing a blocking device or shield to prevent wind, rain, dust, debris or other foreign material from being blown into or induced into the inlet duct 3, from a further set of radial directions, for example "X2".thereby advantageously providing the aforesaid quiescent area "Q" in an otherwise standard and or poor performing co-axial boiler duct. Advantageously the accessory device may be manufactured from a flexible elastomer preferably a UV resistant rubber or polymer material for example.. Chlorosulphonated Polyethylene (CSM), Ethylene Propylene Diene Rubber (EPDM), a silicone or polysiloxane or a fluoroeiastomer. Importantly such manufacturing may be for example by moulding or additive manufacture techniques, even more advantageously such materials provide flexibility in the accessory device such that the orifice 52 can be manufactured of a smaller diameter than the exhaust duct and flexibly expanded over the exhaust duct and by natural resilience and elasticity within the rubber body hold and locate the accessory upon the periphery of the said exhaust duct. Even more importantly the accessory device 50 may be provided with the orifice 52 being offset from the centreline of plate 31 thereby advantageously promoting drainage to and from slot or drain 37. Importantly the said tubular co-axial inlet and exhaust ducts of the boiler flue may themselves be off centre or offset such that the exhaust duct in positioned towards the upper part of the co-axial inlet duct, where such offset is found it is preferably mirrored in the offset to be found in orifice 52. It should be noted that the locating orifice 52 may be located on a centre line or not without hindering the operation of the flow shield device. The drainage slot 37 may or may not be located at the lowest position in plate 31 or may consist of 1, 2 or more slots or drain holes. The accessory device 50 is shown with nubs 60, these nubs being of suitable dimensions to stand off the plate 31 from the inlet opening of the tubular air inlet opening such that placement of the accessory device is automatically and correctly located upon the exhaust duct. Importantly the sleeve or apron portion 33 of the shield device may be advantageously extended both in a linier and or radial to preferably block drafts or wind gusts from problem areas should special applications require such features.

Claims

1, A co-axial flue boiler consisting a combustion device, at least a heat exchanger, a co-axial inlet and or exhaust system consisting a tubular inlet duct and a tubular outlet duct, the distal end of the tubular outlet duct passing through an orifice within at least one plate, said plate located substantially orthogonal to the flow of outlet gasses and predominately upright and spaced apart from said inlet duct opening, said plate further consisting a peripheral attached sleeve or apron substantially linear to and angled towards the direction of inlet air flow such that the said sleeve or apron distal edge abuts to or is in overlapping arrangement with at least a portion of the inlet duct opening of the tubular co-axial air inlet.2 A co-axial flue boiler as claimed in claim 1 wherein the boiler is also of a condensing type.3, A co-axial flue boiler as claimed in claim 1 wherein the plate and sleeve or apron are manufactured as a component part of the co-axial tubular boiler duct.4, An accessory component for a co-axial flue boiler, said boiler consisting at least a combustion device, at least a heat exchanger, a co-axial inlet and or exhaust system consisting a tubular inlet duct and a tubular outlet duct, the distal end of the tubular outlet duct passing through an orifice within the said accessory, said orifice being a close fitting orifice slidably located about the external exhaust duct surface, said orifice located within at least one plate, said plate located substantially orthogonal to the flow of outlet gasses and predominately upright and spaced apart from said inlet duct opening, said plate further consisting a peripheral attached sleeve or apron, said sleeve or apron substantially linear to and angled towards the direction of inlet air flow such that the said sleeve or apron distal edge abuts to or is in overlapping arrangement with at least a portion of the inlet duct opening of the tubular co-axial air inlet.5, An accessory item as claimed in claim 4 wherein the accessory item is a friction fit over an exhaust duct.6, An accessory item as claimed in claim 4 wherein the accessory item is a clamp fit over an exhaust duct.7, An accessory item as claimed in claim 5 or 6 wherein the accessory item is located by at least a nub.8, An accessory item as claimed in claim 4 manufactured from a flexible elastomer preferably a UV resistant rubber or polymer material for example but not limited to; Chlorosulphonated Polyethylene (CSM), Ethylene Propylene Diene Rubber (EPDM), a silicone or polysiloxane or a fluoroelastomer.9, An accessory item as claimed in claim 8 formed by moulding or additive manufacture techniques.10 An accessory device as claimed in claim 8 wherein orifice 52 is of a smaller diameter than the exhaust duct 6, said orifice 52 flexibly expanded over the exhaust duct 6 and therefor by natural resilience and elasticity within the rubber body of the accessory device hold and locate the accessory upon the periphery of the said exhaust duct.

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