Heaters

Abstract: A heater comprises a combustion tube connected to receive gaseous fuel or liquid fuel dispersed within a gaseous carrier gas from a source. The combustion tube communicates with an expansion chamber whose surface is provided with a plurality of openings. The expansion chamber is housed within a perforated container, the internal surface of which is spaced from the external surface of the expansion chamber to receive heating blocks.

Description: This invention relates to heaters and more especially, but not exclusively, to heaters of the type traditionally known as braziers and used mainly out of doors for heating and cooking purposes. In a traditional brazier, charcoal or other solid fuel is burnt in an open topped, cylindrical metal basket or drum and heat is dispersed by radiation and convection from the burning fuel. Characteristics of braziers include a large heat dispersement surface and an appealing visual effect. Disadvantages include the unwelcome smoke and fumes created as the brazier burns and the time taken to light the brazier and to extinguish it after use. The present invention sets out to provide a heater which retains the advantageous characteristics of a brazier but which does not suffer from or at least alleviates the disadvantages referred to above. In the US-A-1 475 450 there is described a heater including a columnar radiating cylinder. According to the present invention in one aspect there is provided a heater which comprises a combustion tube connected to receive gaseous fuel or liquid fuel dispersed within a gaseous carrier gas from a source of such fuel and an expansion chamber in communication with the combustion tube, the heater being characterised in that the expansion chamber has formed in its surface a plurality of openings and is housed within an outer perforated container, the internal surface of the perforated container being spaced from the external surface of the expansion chamber to receive heating blocks. The expansion chamber is preferably positioned about the circumference of the combustion tube. Preferably, the combustion chamber is also housed within the perforated container. The heating blocks may comprise pieces of lava rock or stone. The perforated container may comprise a cylindrical metal drum whose sides are formed from metal wire. The expansion chamber and/or the combustion chamber may be produced from steel, especially stainless steel. The invention will now be described by way of example only with reference to the accompanying diagrammatic drawings, in which:- Figure 1 is a side view in section of a heater in accordance with the invention; and Figures 2 and 3 are side views in section of alternative heaters in accordance with the invention. As will be seen from Figure 1, the illustrated heater comprises a tubular open-ended combustion chamber 1 positioned generally coaxially within a tubular expansion chamber 2 which is closed at its upper and lower ends respectively by a generally circular plate 3 and a ring shaped plate 4 through which the combustion tube 1 projects. The sides of the chamber 2 are perforated to provide a multiplicity of openings 5. These openings may be circular, rectangular or other suitable shape. The combustion chamber and/or expansion chamber may be produced from a stainless steel. The combustion chamber and expansion chamber are housed within a cylindrical container 6 whose sides are perforated to provide a multiplicity of openings 7. The upper end of the container 6 may be closed, open or perforated as for the container sides. The sides of the container 6 may be formed from wire mesh. The assembly of the container, combustion chamber and expansion chamber is supported on a stand including a plurality of legs 9. Positioned between the legs 9 is a cylinder 10 of gaseous fuel, e.g. a liquified gas such as propane. The cylinder is connected via a regulator valve 11 and nozzle 12 to inject gaseous fluid into the open lower end of the combustion tube 1. A piezo electric igniter 13 is positioned within the annular spacing defined by the lower open end of the tube 1, air for combustion purposes being drawn into the tube 1 through this spacing. Shielding may be positioned between the cylinder 10 and the assembly of the combustion and expansion chamber. As will be seen from Figure 1, an annular space is provided between the opposed side faces of the expansion chamber and the container. This space is filled with lava rocks 14 or other heat retaining medium. Lava rocks may also be supported on the plate 3 positioned above the expansion chamber. In use, gaseous fuel from the cylinder 10 passes into the combustion tube at a rate consistent with the setting of the regulator valve 11 and is ignited by operation of the igniter 13. The igniter may be operated remotely. The ignited mix of fuel and air passes through the combustion tube and enters the chamber 2 in which it expands and from which heat is dissipated through the openings 5 to heat the lava rocks 14. Burning of the air fuel mix may cease within the chamber 2 or may continue within the annular space between the opposed surfaces of the chamber 2 and container 6 and, possibly, at the surface of the container itself. The lava rocks quickly become red hot thereby creating the heating and visual effects of a brazier without the disadvantages normally associated therewith. In the arrangement illustrated in Figure 2, (in which the same reference numerals have been used for the same or similar integers of Figure 1) a cylinder 10 of liquid fuel, e.g. paraffin, is employed in place of the gas canister of Figure 1. The cylinder 10 can be pressurised using a hand or foot operated pump 15, the pump being connected to the cylinder through a non-return valve 16. Fuel under pressure is delivered via a tap 17 through a pipe 18 to a vaporising coil 19 and thence to a nozzle 20 through which a jet of fuel is discharged. A shallow container 21 supporting a wick 22 is positioned below the open end of the combustion tube 1. In the arrangement illustrated in Figure 3, a fuel pump 23 is connected to a fuel tank 10 through a pipe 24 to deliver fuel at a high pressure through a pipe 25 to the fuel jet nozzle 20. The heaters shown in Figures 2 and 3 operates effectively in the same way as that described for Figure 1. A restrictor may be provided within the inlet to the combustion tube to enhance combustion efficiency. Also, the combustion tube may be positioned remote from the expansion chamber, the one simply being in communication with the other. The combustion tube may also be positioned outside the confines of the perforated container.

Claims: A heater which comprises a combustion tube (1) connected to receive gaseous fuel or liquid fuel dispersed within a gaseous carrier gas from a source (10) of such fuel and an expansion chamber in communication with the combustion tube, the heater being characterised in that the expansion chamber (2) has formed in its surface a plurality of openings (5) and is housed within an outer perforated container (6), the internal surface of the perforated container (6) being spaced from the external surface of the expansion chamber (2) to receive heating blocks (14). A heater as claimed in claim 1 wherein the expansion chamber (2) is positioned about the circumference of the combustion tube (1). A heater as claimed in claim 1 or claim 2 wherein the heating blocks (14) comprise pieces of lava rock or stone. A heater as claimed in any one of claims 1 to 3 wherein the expansion chamber (2) is closed at its upper end by a circular plate (3) and at its lower end by a ring shaped plate (4) through which the combustion tube (1) projects. A heater as claimed in claim 4 wherein the perforated container (6) comprises a cylindrical metal drum whose sides are formed from metal wire. A heater as claimed in claim 4 or claim 5 wherein the expansion chamber is produced from steel. A heater as claimed in any one of claims 5 to 6 wherein the combustion chamber is produced from steel.

Inventors: STEVENSON JOHN, WATT LINDY PAMELA CAROLINE, STEVENSON, JOHN, WATT, LINDY PAMELA CAROLINE
Applicants: STEVENSON JOHN, WATT LINDY PAMELA CAROLINE, STEVENSON, JOHN, WATT, LINDY PAMELA CAROLINE
Application year: 1997
Main classification: F24C3
IPC codes: F24C3