Abstract: A hot water heater capable of delivering a relatively large quantity of hot water, the quantity being larger than the total volume of the storage capacity of the heater is disclosed.The hot water heater comprises a vessel having an inlet port and an outlet port, a cold water inlet coupled to the inlet port, a hot water outlet line coupled to the outlet port, with heating means for heating water in the vessel, and control means for establishing a flow path between the inlet and outlet lines. The arrangement is such that water flowing in the inlet line is divided between the flow path and inlet port in a predetermined ratio whereby water flowing in the outlet line is, in use, colder than the water passing through the outlet port.

Abstract: A hot water heater comprises a vessel, a heating means for heating water in the vessel, and a control conduit for diverting cold water from the cold water inlet to the hot water outlet so as to reduce the temperature of the hot water delivered from the vessel but to increase the volume. The heater includes a control means for selectively energizing the number of heating elements in accordance with the temperature of the water in the vessel. When the heating means comprises a gas burner, it is arranged to direct combustion gases towards one side of the vessel so as to establish a convection current within the vessel. A novel flue arrangement is also disclosed.

Abstract: A solar energy conversion apparatus which includes a reflective parabolic trough which tracks the sun the control means therefor being such that the trough rotates about a north-south axis alternately to east and west extreme positions until the driving motor is disabled by equal irradiation of a pair of phototransistors. The phototransistors are aligned relative to the axis of the trough such that they are equally irradiated when the sun's rays are concentrated on a heat transfer tube extending along the axis of the trough. The apparatus has a flexible disc drive member to mechanically couple the trough to the drive motor. The heat transfer conduit is of relatively small capacity and a two-phase flow therein is utilized so as to conserve energy.

Abstract: A solar energy conversion apparatus which includes a reflective parabolic trough which tracks the sun the control means therefor being such that the trough rotates about a north-south axis alternately to east and west extreme positions until the driving motor is disabled by equal irradiation of a pair of phototransistors. The phototransistors are aligned relative to the axis of the trough such that they are equally irradiated when the sun's rays are concentrated on a heat transfer tube extending along the axis of the trough. The apparatus has a flexible disc drive member to mechanically couple the trough to the drive motor. The heat transfer conduit is of relatively small capacity and a two-phase flow therein is utilized so as to conserve energy.

Abstract: An instantaneous hot water heater having a coiled heat exchanger (4) through which water to be heated passes. A fuel supply assembly (22) is provided for supplying air and gas to the interior of the exchanger for combustion in such a way that combustion occurs as a series of rapidly occuring pulses at a rate of typically 50 to 100 ignitions per second. There is considerable turbulence in the combustion products whereby good heat exchange takes place enabling very efficient operation.

Abstract: A solar energy conversion apparatus which includes a reflective parabolic trough which tracks the sun the control means therefor being such that the trough rotates about a north-south axis alternately to east and west extreme positions until the driving motor is disabled by equal irradiation of a pair of phototransistors. The phototransistors are aligned relative to the axis of the trough such that they are equally irriadated when the sun's rays are concentrated on a heat transfer tube extending along the axis of the trough. The apparatus has a flexible disc drive member to mechanically couple the trough to the drive motor. The heat transfer conduit is of relatively small capacity and a two-phase flow therein is utilized so as to conserve energy.

Abstract: An internal combustion engine in which a stream of air from a duct (46) to a cylinder (2) so as to flow adjacent to the cylinder walls. The duct (46) is arranged to admit the air only while the exhaust valve (42) is open. The air will circulate against the cylinder walls during the exhaust stroke but at least a portion thereof will remain adjacent the cylinder walls during the subsequent compression stroke. The combustible charge is admitted generally centrally of cylinder and remains stratified with respect to the circulating air. The circulating air maintains the combustible mixture relatively concentrated for good ignition, cushions the igniting gases, assists in maintaining the cylinder walls clean and cools the exhaust valve.

Abstract: Stratification of charge in a four stroke internal combustion engine in which a stream of air issues from a duct (46) and is directed tangentially into a cylinder (2) to circulate about the cylinder adjacent to the cylinder walls. The air is admitted to the cylinder only while the exhaust valve (42) is open. The air circulates adjacent to the cylinder walls during the exhaust stroke and at least a portion thereof remains adjacent the cylinder walls during the subsequent induction and compression strokes. The combustible charge is admitted generally centrally of the cylinder and remains stratified with respect to the circulating air which contains the combustible mixture as a relatively concentrated central core whereby reliable ignition is achieved. The method may also be applied to two-stroke engines and to diesel engines.

Abstract: A pump comprising a pump chamber having an inlet and an outlet, pumping means disposed within the chamber, the pumping means being temperature sensitive and having a first stable position when at a first temperature and a second stable condition when at a second temperature, and means operable to alternately change the temperature of the pumping means from its first to its second temperature whereby fluid within the chamber is pumped out of the outlet by the movement of the pumping means between the first and second stable positions.

Abstract: This specification discloses a reflective trough structure suitable for use in solar energy collecting apparatus. The trough structure comprises an initially flat sheet of aluminium which is resiliently deformed into engagement with concave ribs so that the sheet assumes a parabolic configuration without any need to work the surface of the aluminium sheet which would tend to degrade the reflective properties of the sheet.

Abstract: Solar energy conversion apparatus comprises a solar energy utilization surface, a reflective solar energy concentrator, a tracking device operable to cause the concentrator to track the sun and thereby concentrate solar energy on the utilization surface, a structure defining a shaded zone between the concentrator and the utilization surface such that solar rays reflected from the concentrator toward the utilization surface do not enter the shaded zone when the concentrator is aligned with the sun, wherein the tracking device includes solar energy sensitive elements located within the shaded zone and producing tracking control signals when struck by solar rays when the concentrator is not aligned with the sun.

Abstract: The invention provides solar conversion apparatus comprising concentrating means for concentrating solar energy onto at least one surface of a heat transfer conduit, tracking means for causing the concentrating means to track the sun, the tracking means including radiation sensitive elements which are operable on differential thermal expansion thereof to generate tracking control signals and an electric motor for moving said concentrating means, said motor being responsive to said control signals, tracking movement thus being initiated by thermal radiation but is arrested by optical radiation which is of short response time.

Abstract: A cover for a swimming pool is disclosed comprising first and second layers of plastics material joined together at join zones, to define a plurality of spaces therebetween the spaces being inflated or inflatable, whereby the cover floats when placed on the surface of a pool with the second layer lowermost, at least the second layer being distended away from the join zones and having downwardly projecting crests which in use contact the surface of the pool and the join zones are located above the surface of the pool and wherein drainage holes are formed through the first and second layers at the join zones to provide fluid communication paths from the upper side of the cover to the air space defined between adjacent crests in the second layer and the surface of the pool whereby rainwater drains effectively into the air spaces so defined and then into the pool.

Abstract: Solar tracking apparatus is disclosed which utilizes received solar energy to effect tracking movements, the apparatus comprising focussing means, mounting means mounting the focussing means for tracking movements of the sun, drive means including heat expansible members movable with the focussing means, the heat expansible members being disposed relative to the focussing means so as to receive different amounts of solar radiation from the focussing means when the focussing means is misaligned with the sun so as to produce a differential expansion therein, the drive means being operable on differential expansion of said heat expansible members to cause movement of the focussing means in a direction towards realignment with the sun.

Abstract: An ignition engine comprising a cylinder head, a cylinder and a piston reciprocable therein, first inlet means for admitting a first gas which contains fuel into a central region of the cylinder, and second inlet means for admitting a second gas which does not contain fuel or contains significantly less fuel than the first gas, said second gas being confined generally adjacent to the cylinder walls, and an ignition device located generally centrally of the cylinder head.