Abstract: A fluid heater (100) comprising a storage reservoir (1) for storing heating fluid, a burner (5) for heating the heating fluid and a first heat exchanger (11) located outside said storage reservoir (1). The heater (100) also comprises a first fluid circuit (200) connecting the storage reservoir (1) with the first heat exchanger (11) for carrying heating fluid from the storage reservoir (1), through the first heat exchanger (11) and back to the storage reservoir (1), and a second fluid circuit (300) connecting a first inlet (19) for mains fluid to a first outlet (27) for heated mains fluid via the first heat exchanger (11). The first heat exchanger (11) is adapted to exchange heat between said heating fluid and said mains fluid.

Abstract: Solar energy converting apparatus is disclosed which comprises:(a) focussing means having a focal plane;(b) solar energy absorbing means located along the focal line of the focussing means;(c) a support structure including mounting means for rotating the focussing means about an axis which is co-incident with the focal line of the focussing means; and(d) solar tracking means having an optical plane which is parallel to said focal plane, said tracking means including two heat extensible members which are arranged to receive equal amounts of heat from solar energy when the optical plane is directed at the sun and to receive unequal amounts of heat from solar energy when the optical plane is not directed at the sun, said extensible members being coupled to act between the support structure and the focussing means to cause rotation of the focussing means in accordance with the heat received by respective extensible members.

Abstract: Solar heating apparatus for heating a heat transfer medium comprising a support structure, a light absorbing surface arranged to transmit heat to a heat transfer medium, focussing means mounted on said support structure for focussing solar energy upon the light absorbing surface, and tracking means for tracking movement of the sun and moving the focussing means relative to the support structure to maintain the solar energy focussed upon the light absorbing surface.