Abstract:
Flame-effect heating apparatus comprises a housing with walls defining an air duct extending therethrough. Simulated fuel is supported by the housing, externally of the duct, and at least one flame-effect generator is disposed in the duct. A light source is provided in the housing to illuminate both the simulated fuel and the flame-effect generator. A mirror is supported by the housing so that light reflected by the flame-effect generator is incident thereon. A wall of the housing which defines the air duct, is formed as a viewing screen on which light reflected by the mirror falls, the viewing screen being positioned higher than the simulated fuel. An electric fan causes air to flow through the air duct, so causing operation of the flame-effect generator, and a heat exchanger disposed in the duct warms air passing thereover.

Description:
BACKGROUND TO THE INVENTION 
     (a) Field of the Invention 
     The present invention relates to flame-effect heating apparatus. In particular it relates to flame-effect heating apparatus which is adapted for connection to a domestic water heating system. 
     (b) Description of the Prior Art 
     It has long been thought desirable to combine the aesthetically appealing qualities of a burning solid fuel fire, with the convenience and efficiency of an electric heater. Over the years, so-called “flame-effect” systems have been incorporated into a wide range of electric heating appliances, such as radiant, convector and fan-assisted heaters. 
     The flame-effect is often achieved by a combination of the reflection of light onto a screen, and the creation of a flickering effect by means of a spinner mounted above the light source. Alternatively, or additionally, moveable ribbons may be used to reflect light onto the screen. In use, the ribbons are blown by a fan, and the resultant random motion thus adds to the realism of the flame-effect. 
     However, despite the widespread use of flame-effect systems in conventional electric heaters, until now no such system has been satisfactorily incorporated into a so-called “hydronic” heater. The term “hydronic” is used herein to refer to heating apparatus which heats air by causing it to flow over a heat exchanger, through which is passed a heated liquid. For the purposes of domestic heating, the liquid is normally water, with the heat exchanger being in liquid communication with a domestic water heating system. 
     SUMMARY OF THE INVENTION 
     The present invention provides flame-effect hydronic heating apparatus, which also incorporates improvements to existing flame simulation techniques. 
     According to the present invention, there is provided heating apparatus comprising: 
     a housing having walls which define an air duct extending through said housing; 
     simulated fuel supported by the housing, external of the air duct; 
     flame simulation means comprising at least one flame-effect generator disposed in the air duct, a light source supported by the housing to illuminate both said simulated fuel and said at least one flame-effect generator, a mirror supported by the housing so that light from said light source and reflected by said at least one flame-effect generator is incident thereon, a wall of said housing defining the air duct being formed as a viewing screen on which light reflected by said mirror falls, the viewing screen being positioned at a higher level than said simulated fuel; 
     an electrically-driven fan disposed to cause air to flow through the air duct, so causing operation of said at least one flame-effect generator; and 
     a heat exchanger disposed in said air duct so as to cause air passing thereover to be warmed. 
     The term “flame-effect generator” as used herein includes any flexible material capable of reflecting or obstructing light so as to produce simulated flames on the screen. The flexible material may be in the form of one or more ribbons or strips of lightweight fabric, metallised foil or other suitable material. Such ribbons or strips may be tethered at their upper and/or lower ends. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Preferred embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: 
     FIG. 1 is a cross-sectional view of flame-effect hydronic heating apparatus according to the present invention; 
     FIG. 2 shows the heating apparatus of FIG. 1, with a diagrammatic representation of airflow therethrough when the apparatus is in use; 
     FIG. 3 shows a preferred embodiment of the heating apparatus of FIGS. 1 and 2, having its viewing screen hingedly mounted to enable access to the air duct; 
     FIG. 4 shows a preferred embodiment of the heating apparatus of FIGS. 1 and 2, having its light source mounted on a removable portion of the housing to enable replacement of a light bulb; and 
     FIG. 5 is a schematic diagram showing the connection of the heating apparatus to a domestic water heating system. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In a preferred embodiment of the present invention, there is more than one flame-effect generator, each of which is formed from a piece of lightweight, flexible fabric having an upwardly-tapering profile so as generally to imitate the shape of a flame. The pieces of light weight flexible fabric preferably have a reflective finish, and advantageously are of silk. 
     In order to facilitate the random movement of the flame-effect generators in the air duct, it is preferred that they be tethered at their lower ends only to a grille provided in the air duct above the electrically-driven fan. The upper ends are thus able to move freely in the air-stream. The grille prevents the generators from falling into the fan when said fan is switched off. 
     For convenience, the flame effect generators may be removably attached to the grille, preferably by the provision of co-operating magnetic attachment means on both the generators and the grille. Alternatively a Velcro®-type hook and loop fastener arrangement may be used. 
     The air duct preferably extends from an air inlet located at a lower front part of the housing, to an air outlet located at an upper front part of the housing, with a forward-facing wall of the housing forming part of the air duct and serving as the viewing screen. 
     Preferably, a single electrically-driven fan is used both to cause operation of the flame-effect generators and to direct air over the heat exchanger. By contrast, conventional non-hydronic electric heaters incorporating similar flame-effect systems usually employ a first fan to operate the flame-effect generators and a second fan to pass air over the heating element. 
     In preferred embodiments, the electrically-driven fan is disposed in the air duct adjacent to the air inlet, the heat exchanger is disposed adjacent to the air outlet, and the flame-effect generators are disposed therebetween. It is currently most preferred that the fan be disposed at the bottom of a flame-effect chamber defined within a substantially vertical portion of the air duct, the nozzle of the fan being directed upwards into said chamber. When the apparatus is in use, air is drawn in through the inlet by the fan, turned through substantially 90°, and blown up through the flame-effect chamber and over the heat exchanger, before exiting through the outlet. 
     The heat exchanger preferably has connectors to permit the liquid communication thereof with a domestic water heating system, when installed. 
     In preferred embodiments of the present invention, the apparatus is provided with control means, arranged automatically to switch on both the electrically-driven fan and the electrically-driven light source upon activation of the water heating system. Preferably, the control means comprises a thermostat, such that the fan and light source are activated when the water in the heating system is heated to a pre-selected temperature. It is currently preferred that this activation temperature should be substantially 47° C. 
     The control means may desirably also permit the electrically-driven fan and the light source to be switched on independently of the temperature of water in the water heating system. In this way the present invention may be used to simulate the visual appearance of a burning solid fuel fire, even when no heating is required. 
     In a most preferred embodiment of the present invention, the control means is adapted to operate the electrically-driven fan at two or more pre-selected speeds. Operating the fan at a higher speed, increases the flow of air over the heat exchanger, thus leading to an increase in the heat given out by the heating apparatus. Additionally, the flame-effect generators are caused to move faster, and the resultant reflections increase the flickering of the simulated flames. This creates the illusion that the increased heat output results from the intensified flame-effect, thus enhancing the realism of the flame-effect. 
     In currently preferred embodiments of the present invention, the viewing screen has a forward-facing surface which is generally non-reflective and a rearwardly-directed surface which is generally diffusing. In order that the flame-effect generators may easily be removed for cleaning, it is preferred that the viewing screen is hingedly and/or removably mounted on the housing, thus enabling access to the air duct. 
     Similarly, in a preferred embodiment, the light source comprises a fitting for a light bulb, said fitting being mounted on a removable portion of the housing, to enable replacement of the light bulb. 
     A particular embodiment of the heating apparatus of this invention will now be described with reference to accompanying FIGS. 1 to  5 . 
     Referring initially to FIG. 1, there is shown heating apparatus, generally indicated  10 , having a housing  11 , within which is defined an air duct  12 . The air duct  12  extends from an inlet  13 , located at a lower front part of the housing  11 , to an air outlet  14 , located at an upper front part of the housing  11 . 
     A cavity  15  is defined externally of the air duct  12 , by a transparent or translucent portion  16  of the housing  11 . A light source  17  located within the cavity  15 , is disposed so as to illuminate both simulated fuel  18 , and also flame-effect generators  19 , located in the air duct  12 . The flame-effect generators  19  are formed from pieces of silk having a flame-shaped profile. The simulated fuel  18  is supported by the transparent or translucent portion  16  of the housing  11 . 
     A mirror  21  provided on a rear wall of the air duct  12 , is disposed to reflect light from the light source  17  and the flame-effect generators  19 , onto a viewing screen  22  which, together with a rear wall of the housing  11 , defines a flame-effect chamber  23  in the air duct  12 . 
     An electrically-driven fan  24  having a nozzle  25  is located in the air duct  12 , and is arranged such that said nozzle  25  is directed upwards towards the flame-effect chamber  23 . Mounted immediately above the fan  24  is a grille  26 , which extends across the air duct  12 , and has a peg  27  upstanding therefrom. The flame-effect generators  19  have a lower end  28  which is removably attached to the upstanding peg  27 , by co-operating magnetic attachment means provided thereon. Alternatively, the upstanding peg  27  and the lower end  28  of the flame-effect generators  19  may each be provided with co-operating hook and loop fasteners, such as those sold under the trade mark Velcro®. 
     Extending across an upper portion of the flame-effect chamber  23  of the air duct  12  is a heat exchanger  29 . The heat exchanger  29  is provided with an air bleeding valve  32  and thermostatic control means  33 , which control means are operatively linked with the fan  24 , the light source  17 , and a control switch  34  located externally on the housing  11 . The heat exchanger  29  is also provided with connectors  31  to permit the linking thereof with a domestic water heating system  46 , as shown in FIG.  5 . Extending across an upper portion of the flame-effect chamber  23  of the air duct  12  is a heat exchanger  29 . The heat exchanger  29  is provided with an air bleeding valve  32  and thermostatic control means  33 , which control means are operatively linked with the fan  24 , the light source  17 , and a control switch  34  located externally on the housing  11 . The heat exchanger  29  is also provided with connectors  31  to permit the linking thereof with a domestic water heating system  46 , as shown in FIG.  5 . 
     During use of the heating apparatus, as shown in FIG. 2, when the temperature of the water in the heat exchanger  29  reaches a pre-selected temperature, the fan  24  and the light source  17  are switched on automatically by the thermostatic control means  33 . The fan  24  draws air from the ambient into the air duct  12 , through the air inlet  13  located at a lower front part of the housing  11 . A decorative facia  35  may be mounted on the front part of the housing  11 . As the air is drawn through the electrically-driven fan  24 , the direction of the air flow (indicated by the arrows) is turned through substantially 90°, and the air is then blown upwards through the flame-effect chamber  23 , causing motion of the flame-effect generators  19 . 
     At the same time, the light source  17  illuminates the flame-effect generators  19  and the simulated fuel  18  through the transparent or translucent portion  16  of the housing  11 . Light from the light source  17  and the flame-effect generators  19  is reflected by the mirror  21  onto the viewing screen  22  which is light-diffusing at its rear surface  47 , and non-reflective at its forward facing surface  48 . An observer, generally indicated at  36 , therefore sees a diffuse image of simulated flames dancing randomly on a portion of the viewing screen  22  immediately above the simulated fuel  18 . 
     The fan  24  drives the air past the flame-effect generators  19 , and on to the heat exchanger  29 . The air is heated as it passes over the heat exchanger  29 . The direction of the air flow is then turned again through substantially 35° by a sloping cowl  37  at the end of the air duct  12  adjacent to the outlet  14 . The heated air is then returned to the ambient through the outlet  14 , immediately above the simulated flames on the viewing screen  22 , and the simulated fuel  18 . The observer  36  thus experiences the illusion that the heat is emanating from the simulated flames on the viewing screen  22 . 
     Alternatively, the control switch  34  may be used to override the thermostatic control means  33  such that the heating apparatus  10  operates in “flame-effect only” mode. In this mode of operation, the electrically-driven fan  24  and the light source  17  are switched on, thus providing the simulated flames on the viewing screen  22 , but no heating of air occurs due to inactivity of the water heating system. 
     The control switch  34  may also be used when the heating apparatus  10  is operating in its normal heating mode, to vary the speed of rotation of the electrically-driven fan  24 . By causing the fan  24  to operate at a higher speed, the flow of air over the flame-effect generators  19  and the heat exchanger  29  is increased. Consequently, the simulated flames on the viewing screen  22  appear to move quicker, whilst a greater amount of heat is emitted through the outlet  14 . For the observer  36 , this adds to the realism of the illusion that the heat emanates from the simulated flames. 
     Referring now to FIG. 3, it will be seen that the viewing screen  22  is mounted by a hinge  38  at its lower end, to the transparent or translucent portion  16  of the housing  11 . The upper end of the viewing screen  22  is releasably attached to a portion of the housing  11  in front of the heat exchanger  29 , by means of a catch  39 . 
     The screen  22  can thus be detached from the housing  11  at its upper end by means of the catch  39 , and hinged forwards about hinge  38 , in order that access may be gained to the flame-effect chamber  23 . The flame-effect generators  19  may thus be removed by detaching the lower end  28  thereof from the upstanding peg  27 . 
     Referring now to FIG. 4, in this embodiment of heating apparatus  10 , the light source  17  comprises a light bulb  41 , and a fitting  42  for said light bulb  41 . The fitting  42  is mounted on a removable portion  43  of the housing  11 . The front of this removable portion  43  forms part of the decorative facia  35 , and has a handle  44 . The removable portion  43  is normally held in place on the main part of the housing  11  by a retaining tab  45  which engages with a complementary slot (not shown) in the housing  11 . The light source  17  is thus normally held in place in the cavity  15 . When the light bulb  41  is to be changed, the removable portion  43  may be withdrawn from the main part of the housing  11  by pulling handle  44  forwards and upwards, until the removable portion  43  is clear of the housing  11 .