GB2230081A

GB2230081A - Convection space heating unit

Info

Publication number: GB2230081A
Application number: GB9003457A
Authority: GB
Inventors: Francis Clifford Wilcox
Original assignee: Individual
Current assignee: Individual
Priority date: 1989-02-17
Filing date: 1990-02-15
Publication date: 1990-10-10
Anticipated expiration: 2010-02-15
Also published as: GB9003457D0; GB2230081B; GB8903693D0

Abstract

Apparatus for use with a fire comprises a base plate 18 which sits on the floor of a fireplace, a back portion 22 which extends up the fireback, and a top portion 26 which extends forward to the top of the fireplace. These components are hollow and form between them a duct which extends from an inlet 12 across the floor of the fireplace, up the back of the fireplace and across the top of the fireplace to an outlet at 14. The cross-section of the duct reduces by a taper at 38 so that the heated air accelerates within the duct and is projected out of the outlet 14 into the room with an increased velocity. The apparatus may be used with or incorporated in a simulated open fire or a conventional gas fire. <IMAGE>

Description

Apparatus for use with an Open Fire The present invention is concerned with apparatus for use with a fire, and especially but not exclusively with real or simulated open fires.

A major source of inefficiency in a fire is the heat lost up the chimney and into the fireplace brickwork or surrounds. It is an object of the present invention to improve the efficiency of a fire.

According to the present invention there is provided apparatus for use with a fire, comprising an inlet for cold air, an outlet for heated air, and a duct through which air may pass from the inlet to the outlet, the duct being so located, in use, as to allow heat from the fire to cause air to move through the dut, and the duct reducing in cross-section part way along, to cause air to accelerate before leaving the outlet.

Preferably the said reduction in cross-section occurs at a position in the duct which, in use, is downstream of the position at which the rate of heat exchange between the fire and the duct is at a maximum.

The walls of the duct preferably taper together to form the reduction in cross-section, thereby maintaining a smooth air flow across the reduction.

The walls of the duct may be more heavily insulated from the fire downstream than upstream of the reduction in cross-section, whereby to provide an enhanced temperature gradient across the reduction in cross-section.

Preferably the duct is defined in part by a base portion which is located, in use, under the fire.

Preferably the inlet is located in the base portion. The inlet, in use, is preferably located at or near the hearth of the fireplace in which the apparatus is installed. Preferably the inlet draws air from the room being heated by the fireplace in which the apparatus is installed.

The duct may be defined in part by a back portion which, in use, extends generally upwardly and adjacent the fireback. Preferably the back portion and the base portion are adjustably connected. The said portions may be telescopically connected to permit adjustment of the overall height of the apparatus. The apparatus may comprise locking means operable to lock the relative positions of the said portions.

Preferably the back portion is defined, at least in part, by a portion which is removable for replacement.

Preferably the reduction in cross-section of the duct occurs at a location which is within the back portion.

The back portion may be so formed as to conform to the shape of the fireback.

The duct may be defined in part by a top portion which, in use, extends across the top of the fire to the outlet. Preferably the top portion is adjustably connected to the back portion. The top and back portions may be telescopically connected to permit adjustment of the overall size of the apparatus. The apparatus may comprise second locking means operable to lock the relative positions of the top and back portions. The top portion may have a decorative surface which extends at least part way across the front of the fireplace, and through which the air leaves the outlet. Preferably the outlet is located at or near the top of the fireplace an which the apparatus is installed. The outlet may supply air to the room being heated by the fireplace in which the apparatus is installed.

The apparatus may comprise a baffle at or near the outlet and so arranged as to deflect smoke from an open fire back into the fireplace.

The apparatus is preferably removable from the fireplace to leave the fireplace able to function. The apparatus is preferably cast in iron.

An embodiment 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 perspective view of apparatus according to the present invention and for use with an open fire; Fig. 2 is a vertical section through a fireplace in which the apparatus of Fig. 1 has been installed.

Referring to the accompanying drawings there is provided apparatus 10 for use with an open fire, comprising an inlet 12 for cold air, and outlet 14 for heated air, and a duct (indicated generally at 16) through which air may pass from the inlet 12 to the outlet 14. The duct 16 is so located, in use, within a fireplace as to allow heat from the fire to cause air to move through the duct 16, and the duct 16 reduces in cross-section part way along, to cause air to accelerate before leaving the outlet 14.

In more detail, the apparatus 10 is a self-supporting unit which may be installed in an existing fireplace (as shown in Fig. 2) and is manufactured from any suitable material, for example cast iron.

The air duct 16 comprises a hollow base plate 18, which extends, in use, under a fire grate 20. A hollow back portion 22 extends up from the base plate 18 in front of the fireback. A hollow top portion 26 extends the duct from the back portion 22, to the outlet 14.

The inlet 12 is in the form of a long, narrow, horizontal slot formed in the front of the base plate 18.

The base plate 18, extends from the inlet 12 to taper horizontally according to the shape of the fireplace with which it is intended to be used.

A sleeve 28 which is rectangular in horizontal cross-section extends up from the upper surface 30 of the plate 18 at or near the back of the plate 18. The sleeve 28 accommodates the lower end of the back portion 22 in a telescopic manner to allow adjustment of the overall height of the apparatus 10 according to the height of the fireplace in which the apparatus 10 is to be installed.

The desired height of the back portion is set by a bolt 34 locatable through appropriate pairs of apertures 36 formed in the sleeve 28.

The back portion 22 extends generally vertically up from the base plate 18. Part way along the back portion 22, the duct 16 reduces in cross-sectional area primarily, as a result of a reduction in the width thereof. That is, the shorter sides of the cross-section taper together along a short length of the duct 16, to reduce the length of the longer sides of the cross-section. The reduction in cross-section of the duct 16 occurs, in use, at a position along the back portion 22, downstream of the position at which the rate of heat exchange between the fire and the duct 16 is at a maximum. This position of the reduction is approximately half way up the back portion 22.

The tapering portion 38 ensures that the reduction is not abrupt, and so maintains smooth air flow across the reduction. The tapering portion leans forward to conform to the shape of the hump in a conventional fireback 24. The upper part 40 of the back portion 22, above the tapering section 38, again extends substantially vertically until shortly before its upper end, where it turns over to extend forward, above the base plate 18. The top portion 26 extends from the forwardly projecting section of the part 40. Further telescopic adjustment is provided at 42 between the back portion and the top portion 26 to allow adjustment of the overall size of the apparatus 10 according to the dimensions of the fireplace in which the apparatus is to be used.

The tapering section 38 and the upper part 40 of the back portion 22 may carry an insulating layer (not shown), at least on the side facing the fire when in use to restrict further heating of the air within this region of the duct.

The outlet 14 is formed in the top portion 26. The top portion 26 increases significantly in width around the outlet 14 to form a decorative face which extends across the front of the fireplace. Air leaving the outlet passes through a grill 48 forming part of the decorative face.

Fig. 2 shows the apparatus of Fig. 1 installed in a fireplace. The base plate 18 rests on the floor of the fireplace, with the inlet 12 at or near the hearth 44 of the fireplace. The fire grate 20 stands on the upper surface 30 of the base plate 18. Alternatively, the legs 46 of the grate 20 may straddle the plate 18. The back portion 22 extends up from the base plate 18, behind the grate 20 and up the fireback 24. The adjustment between the base plate 18 and the back portion 22 is carried out before installing the apparatus 10. The tapering portion 38 leans forward to permit the duct 16 to conform to the shape of the fireback 24. The upper part 40 of the back portion extends up to and then across the bottom of the chimney. The top portion 26, is located at the top of the fireplace to place the outlet 14 in the room being heated by the fireplace. The grill 48 extends a little way above the duct 16 to form a lip 50. The lip 50 may slightly overlap the corner 52 between the fireplace and the wall of the room to provide a neat appearance and also to assist in permanent fixture of the apparatus 10 in position if desired.

The top portion 26 also carries a skirt 54 which extends across the front of the fireplace, beneath the outlet 14, to act as a baffle and deflect smoke back into the fireplace.

When installed therefore, the base plate 18, the back portion 22 and the top portion 26 form between then a continuous duct which extends from the inlet 12, across the floor of the fireplace (underneath the grate), up the fireback, and across the roof of the fireplace to the outlet 14.

In use, a fire lit in the grate 20 will heat the duct, principally in the part of the back portion 22 below the tapering portion 38. This heating leads to the heating of the air within, thereby causing the air to move. The heated air tends to rise and passes up the back portion 22, being replaced by relatively cold air entering from the room through the inlet 12.

The heated air rising through the back portion 22 encounters the tapering portion at which the cross-section of the duct reduces. As the heated air passes through the taper it is accelerated by virtue of the reduction in cross-section. This acceleration is enhanced by the temperature gradient which is produced across the reduction by the provision of insulation. The acceleration of the air is believed to be a "Venturi" type effect.

The accelerated, heated air then moves through the rest of the duct and is expelled into the room through the outlet 14.

The enhanced flow rate of the accelerated air gives a greater effective heat output from the open fire because the heat is projected into the room to provide more uniform heating of the room.

Many variations and modifications may be made to the apparatus without departing from the spirit and scope of the invention.

The apparatus 10 has been described herein with reference to an open fire, however, the apparatus is equally applicable for use in with other types of fire such as a simulated open fire (for example a gas fire comprising ceramic coals) and conventional gas fires.

The apparatus may be permanently incorporated in a simulated open fire or a conventional gas fire.

In addition to providing for some adjustment in the apparatus described above, it may be desirable to alter the size and shape of the components of the apparatus according to the fireplace for which the apparatus is designed. Many forms of adjustment means may be used, and one or both may be omitted, or further adjustments may be incorporated. The apparatus may be decorated according to taste.

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. Apparatus for use with a fire, comprising an inlet for cold air, and outlet for heated air, and a duct through which air may pass from the inlet to the outlet, the duct being so located, in use, as to allow heat from the fire to cause air to move through the duct, and the duct reducing in cross-section part way along, to cause air to accelerate before leaving the outlet.

2. Apparatus according to claim 1, wherein the reduction in cross-section occurs at a position in the duct which, in use, is downstream of the position at which the rate of heat exchange between the fire and the duct is at a maximum.

Apparatus according to claim 1 or 2, wherein the walls of the duct taper together to form the reduction in cross-section, thereby maintaining a smooth air flow across the reduction.

4. Apparatus according to any preceding claim, wherein the walls of the duct are more heavily insulated from the fire downstream than upstream of the reduction in cross-section, whereby to provide an enhanced temperature gradient across the reduction in cross-section.

5. Apparatus according to any preceding claim, wherein the duct is defined in part by a base portion which is located, in use, under the fire.

6. Apparatus according to claim 5, wherein the inlet is located in the base portion.

7. Apparatus according to claim 6, wherein the inlet, in use, is located at or near the hearth of the fireplace in which the apparatus is installed.

8. Apparatus according to any preceding claim, wherein the inlet draws air from the room being heated by the fireplace in which the apparatus is installed.

9. Apparatus according to any preceding claim, wherein the duct is defined in part by a back portion which, in use, extends generally upwardly and adjacent the fireback.

10. Apparatus according to claim 9 and any of claims 5 to 8, wherein the back portion and the base portion are adjustably connected.

11. Apparatus according to claim 10, wherein the said portions are telescopically connected to permit adjustment of the overall height of the apparatus.

12. Apparatus according to claim 10 or 11, wherein the apparatus comprises locking means operable to lock the relative positions of the said portions.

13. Apparatus according to any of claims 10 to 12, wherein the back portion is defined, at least in part, by a portion which is removable for replacement.

14. Apparatus according to any of claims 10 to 13, wherein the reduction in cross-section of the duct occurs at a location which is within the back portion.

15. Apparatus according to any of claims 10 to 14, wherein the back portion is so formed as to conform to the shape of the fireback.

16. Apparatus according to any preceding claim, wherein the duct is defined in part by a top portion which, in use, extends across the top of the fire to the outlet.

17. Apparatus according to claim 16, wherein the top portion is adjustably connected to the back portion.

18. Apparatus according to claim 17, wherein the top and back portions are telescopically connected to permit adjustment of the overall size of the apparatus.

19. Apparatus according to claim 18, wherein the apparatus comprises second locking means operable to lock the relative positions of the top and back portions.

20. Apparatus according to any of claims 16 to 19, wherein the top portion has a decorative surface which extends at least part way across the front of the fireplace, and through which the air leaves the outlet.

21. Apparatus according to any preceding claim, wherein the outlet is located at or near the top of the fireplace in which the apparatus is installed.

22. Apparatus according to any preceding claim, wherein the outlet supplies air to the room being heated by the fire in the fireplace in which the apparatus is installed.

23. Apparatus according to any preceding claim, wherein the apparatus comprises a baffle at or near the outlet and so arranged as to deflect smoke from an open fire back into the fireplace.

24. Apparatus according to any preceding claim, wherein the apparatus is removable from the fireplace to leave the fireplace able to function.

25. Apparatus according to any preceding claim, wherein the apparatus is cast in iron.

26. Apparatus for use with a fire, substantially as described above with reference to the accompanying drawings.

27. Any novel subject matter or combination including novel subject matter disclosed, whether or not within the scope of or relating to the same invention as any of the preceding claims.