GB2236176A

GB2236176A - Gas fire and back boiler combinations

Info

Publication number: GB2236176A
Application number: GB9016677A
Authority: GB
Inventors: Ian Deakin
Original assignee: Glow Worm Ltd
Current assignee: Glow Worm Ltd
Priority date: 1989-07-28
Filing date: 1990-07-30
Publication date: 1991-03-27
Anticipated expiration: 2010-07-30
Also published as: GB9016677D0; GB2236176B

Abstract

A heating appliance comprises a fire unit 10, a back boiler unit 19 and gas burner assemblies 14, 21 associated with both units. A baffle assembly including plates 30, 32 above the back boiler unit deflects products of combustion to a flue 6. A spigot 15 diverts products of combustion from the fire to the same flue. The arrangement directs a down-draught away from the burner assemblies and discharges same through the front of the fire unit at an upper level so that the fire unit can be inset into a fire opening and still meet safety requirements on venting of down-draughts. The rearwardly directed discharge outlet or spigot 15 for combustion products from the fire unit is at an upper region and is adapted to locate in an opening 23 above the-boiler unit with which it is substantially co-extensive. <IMAGE>

Description

Heating Appliances This invention relates to heating appliances and especially to gas fired space heating appliances incorporating back boiler units for water heating purposes.

Gas fired heating appliances require to meet stringent safety standards and in particular require to include means to prevent build-up of combustion products within the fire in the event of down-draught conditions causing a flow of air down the flue through which products of combustion are normally discharged. In the case of gas fires fitted with back boiler units this requirement has hitherto been met by providing a space in the fire opening around the back boiler unit and arranging for down-draughts to be directed into this space and then discharged outwardly between the sides of the appliance and the wall of the room or like location in which it is fitted. This requires that the fire itself is fitted to the face of the wall and not inset into the opening in which the back boiler unit is fitted.

Constructions of this kind are wasteful of space and place limitations on the construction of the appliance. Because of the need to vent down-draughts from the sides of the appliance the fire must be located forwardly of the wall of the room and therefore projects substantially into the room itself. Aesthetic considerations then place constraints on the size of the fire which would be removed if the fire could be inset into the fire opening. However hitherto this has not seemed practicable since it would not then be possible to deal satisfactorily with down-draught conditions.

The present invention is concerned with a combined fire and back boiler assembly in which the fire can be inset into the fire opening while the unit nevertheless complies with safety requirements relating to the venting of down-draughts.

The invention provides a heating appliance comprising a fire unit, a back boiler unit, gas burner assemblies associated with both said units, means above the back boiler unit to deflect products of combustion to a flue, means above the fire unit to divert products of combustion from the fire to the same flue, and means to deflect down-draughts from the flue away from said burner assemblies and to disc-harge same through the front of the fire unit at an upper level.

The fire unit preferably incorporates a rearwardly directed discharge outlet for combustion products at an upper region thereof, the discharge outlet being adapted to locate in an opening above the boiler unit with which the outlet is substantially co-extensive. Preferably said outlet and said opening are substantially greater in area than the flue outlet conventionally provided on gas fire units whereby substantially all the air required by the appliance to dilute flue products enters the flue area through said outlet.

By virtue of the provisien of a discharge outlet of substantial cross-sectional area, not only does essentially all of the air required by the appliance to dilute flue products enter the flue through said outlet, but substantially all of the deflected down-draught is collected by said outlet for discharge through the upper front of the fire unit.

Preferably said means for deflecting down-draughts comprises baffle means interposed between said flue and said boiler unit and operable to direct down-draughts from the flue over said boiler unit and out through the front of the fire unit.

The invention also provides a method of controlling flue discharge and down-draughts in a heating appliance comprising a combined gas fire and back boiler assembly, the method comprising directing combustion products from both said gas fire and said back boiler into a common flue during normal operation of the appliance and diverting down-draughts over the top of said boiler and discharging same through the front of the fire by way of an outlet at an upper level thereof.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawings, in which: Fig. 1 is a vertical cross-section through a heating appliance comprising a gas fire and back boiler constructed according to the invention showing the flow of combustion products under normal up-draught conditions; and Fig. 2 is a similar view showing the flow of combustion products under down-draught conditions.

Referring to the drawings, the appliance is shown mounted in a fire opening 5 in a wall or. like structure provided with a chimney or flue 6 through which combustion products from the appliance may be discharged to atmosphere. The appliance is mounted on a hearth 7 and fits closely against the back wall 8 of the fire opening.

The appliance comprises a fire unit 10 comprising a front section 11 disposed forwardly of the fire opening 5 and a rear section 12 located within the opening. A fire bed 13 comprising incandescent material made to resemble artificial coal, logs or other fuel is mounted in the lower region of the fire unit and a gas burner unit 14 is mounted beneath and forwardly of the fuel bed. A discharge outlet or spigot 15 of substantial cross-sectional area projects rearwardly from the fire unit at a level above that of the fire bed 13.

A A back boiler unit 19 is mounted behind the fire unit 10 and a separate burner assembly 21 is located beneath the boiler unit. The boiler unit comprises a heat exchanger 20 having flue passages through which combustion products from the burner assembly 21 may pass in heat exchange relationship with water circulating through the boiler and serving a hot water and/or central heating system. The upper region of the boiler unit comprises a housing 22 which incorporates an assembly of baffles and includes a forwardly directed opening 23 which engages and is substantially co-terminus in extent with the spigot 15 projecting rearwardly from the fire unit 10. A flue outlet 24 is mounted on the housing 22 and serves to discharge products of combustion to the flue 6.

The baffle assembly comprises a lower inclined baffle plate 30 spaced above the top of the heat exchanger 20 and extending upwardly and rearwardly but terminating short of the rear wall of the housing 22 to leave an opening 31 through which combustion products from the boiler may pass in a generally upward direction. A generally horizontal baffle plate 32 is mounted above and to the rear of the rear end of the baffle plate 30 and is provided with an upwardly directed lip 33. The baffle plate 32 projects across the flue outlet 24 by a distance approximately equal to half the diameter of the latter and the spacing between the upper free end of the baffle plate 30 and the under surface of the lip 33 of the baffle plate 32 defines an opening 34 through which combustion products from the boiler may pass en route to the flue outlet 24.

The baffle plate 30 is provided with a forwardly and upwardly directed extension 30A projecting into the spigot 15. This extension has been found to contribute significantly to satisfactory diversion of down-draughts into the spigot 15 and hence through the upper region of the fire unit. Both the baffle plates 30 and 32 extend across the full width of the housing 22.

In normal operation of the appliance (shown by the arrows in Fig. 1), products of combustion 'A' from the burner 14 pass over the fuel bed 13 in an upward direction and are drawn thro-ugh the outlet 15, housing 22 and outlet 24 into the flue 6 from whence they are discharged to atmosphere. Products of combustion 'B' from the burner assembly 21 pass through the heat exchanger 19, around the baffles 30 and 32 and through outlet 24 to the flue 6. Secondary air 'C' to dilute the combustion products also reaches the flue through the front of the fire, the spigot 15, housing 22 and outlet 24. Thus in normal operation the combustion products from both the fire and boiler are directed into the flue 6 and discharged to atmosphere.

In the event of a down-draught in the flue 6, which usually arises in the case of flues which are badly sited relative to other high structures or due to unusual weather conditions, air 'D' (Fig. 2) flows down the flue 6 towards the appliance. If such down-draughts were to reach the burner assemblies 21 and 14 they would interfere with efficient burning and give rise to conditions which could be dangerous if not detected in time. This is prevented by the baffle arrangement in the housing 22 of the boiler unit. The baffle plate 32,33 tends to deflect down-draughts forwardly and the baffle plate 30 prevents downward movement through the heat exchanger 19 of the boiler unit.The combustion products 'A' from the fire unit and the combustion products 'B' from the boiler unit mix with the down-draught air 'D' in the housing 22 of the boiler unit 19, from which the combined flow is discharged by way of the outlet 15 through the upper front region of the fire unit into the room in which the appliance is fitted. The down-draught is therefore deflected away from the burner assemblies 21 and 14 and passes out of the appliance thereby preventing build-up of conditions which might impede proper combustion of the fuel.

The appliance described has a number of advantages compared with combined gas fire and back boiler units hitherto proposed. A principal advantage arises from the fact that there is no need to leave spaces between or around the boiler and fire to cater for down-draught conditions. This enables the fire unit to be partly inset into the fire openihg. Alternatively it would permit an existing forwardly projecting fire to be extended rearwardly to increase the area of the incandescent fuel bed. In the former case an aesthetic improvement is attained and in the latter an increase in useful area of the fuel bed. The arrangement described is particularly advantageous in that the baffle assembly may be mounted above an essentially standard boiler unit thereby eliminating the need to produce special boiler constructions.The baffle and spigot assembly is also of essentially simple and hence inexpensive construction.

Various modifications may be made without departing from the invention. For example alternative means may be employed for diverting and discharging down-draughts through the front of the fire. Where assemblies of baffles are utilized these may be differently constructed and positioned from those in the embodiment. Different sizes, shapes and constructions of fire discharge outlet or spigot may also be employed and the back boiler and fire units may take many different forms without departing from the scope of the invention.

Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.

Claims

1. A heating appliance comprising a fire unit, a back boiler unit, gas burner assemblies associated with both said units, means above the back boiler unit to deflect products of combustion to a flue, means above the fire unit to divert products of combustion from the fire to the same flue, and means to deflect down-draughts from the flue away from said burner assemblies and to discharge same through the front of the fire unit at an upper level.

2. A heating appliance according to claim 1 wherein said fire unit incorporates a rearwardly directed discharge outlet for combustion products at an upper region thereof, the discharge outlet being adapted to locate in an opening above the boiler unit with which the outlet is substantially co-extensive.

3. A heating appliance according to claim 2 wherein the cross-sectional area of said opening is such that substantially all the air required by the appliance to dilute flue products enters the flue area through said outlet.

4. A heating appliance according to any of claims 1 to 3 wherein said means for deflecting down-draughts comprises baffle means interposed between said flue and said boiler unit and operable to direct down-draughts from the flue over said boiler unit and out through the front of the fire unit.

5. A heating appliance according to claim 4 wherein -said boiler unit includes a heat exchanger surmounted by a housing incorporating said baffle means.

6. A heating appliance according to claim 5 wherein said baffle means includes a lower baffle spaced above the top of said heat exchanger, extending upwardly and rearwardly and terminating short of the rear wall of said housing to define an opening through which combustion products from the boiler may pass in a generally upward direction.

7. A heating appliance according to claim 6 wherein said lower baffle includes a forwardly directed extension at the lower end thereof proje-cting into said rearwardly directed discharge outlet of said fire unit.

8. A heating appliance according to any of claims 5 to 7 wherein said baffle means includes a generally horizontal baffle plate mounted above and to the rear of the rear end of said inclined baffle.

9. A heating appliance according to claim 8 wherein said generally horizontal baffle plate includes an upwardly directed lip at its forward edge.

10. A heating appliance according to claim 8 or 9 wherein said housing includes a flue outlet connectable to said flue, said generally horizontal baffle plate projecting across said flue outlet by a distance approximately equal to half the diameter thereof.

11. A heating appliance substantially as hereinbefore described with reference to the accompanying drawings.

12. A method of controlling flue discharge and down-draughts in a heating appliance comprising a combined gas fire and back boiler assembly, the method comprising directing combustion products from both said gas fire and said back boiler into a common flue during normal operation of the appliance and diverting down-draughts over the top of said boiler and discharging same through the front of the fire by way of an outlet at an upper level thereof.

13. A method of controlling flue discharge and down-draughts in a heating appliance comprising a combined gas fire and boiler assembly substantially as hereinbefore described.

14. Any novel subject matter or combination including novel subject matter disclosed in the foregoing specification or claims and/or shown in the drawings, whether or not within the scope of or relating to the same invention as any of the preceding claims.