Abstract: A compact, gas-fired water heater in which a reservoir of bulk water is indirectly heated by a gas burner-fired immersion tube and directly heated by mutual contact between the hot flue gases from the immersion tube outlet and feed water droplets as they pass each other in contra-flow through the apertures in a plurality of plates and through a packed bed of graded solid particles or Rashig rings. The packed bed may also include suitable chemicals for modifying the quality of the stored water. One or more calorifiers may be located in the reservoir with limited direct heat conduction contact with the immersion tube.

Abstract: A fuel-fired fluid heating appliance, such as a gas-fired boiler (FIG. 1) is provided for heating a fluid such as water circulating in a central heating system. The boiler includes a flue 4 for discharging the combustion products, e.g. exhaust gas, to atmosphere by way of a heat exchanger 8 incorporated within a portion 6 of the flue 4 external of the boiler housing 1. The heat exchanger 8 is provided with an inlet 16 to receive water from a return flow pipe 36 and an outlet 17 to discharge the water to the inlet 35 of the boiler primary heat exchanger 3. The heat exchanger 8 (FIG. 2) is provided with a number of ducts 18 along which the exhaust gas travels to transfer its heat to the water circulating within compartments 29 to 33 within the heat exchanger housing 15. The external portion 6 of the flue 4 is disposed at an angle of 20.degree. downwardly to the horizontal so that any exhaust gas condensing in the heat exchanger 8 flows down the flue base 9 to a discharge spout 10 and collector weir 11.

Abstract: A heat exchanger of the regenerative type comprising a matrix of heat storage elements and a support structure therefor comprising a plurality of support bars and a support rim upon which the bars are located; at at least one end each element of the matrix comprising a heat storage block having a plurality of gas flow passages extending therethrough from end to end of the block and being adapted to co-operate with at least one of the support bars for locating and supporting the blocks with respect to the rim in parallel generally side-by-side relation with one another.

Abstract: A process is described for producing a composite metal film in which metalliferous particles and polymer particles are co-deposited on a substrate, the proportion of metalliferous particles being such that the metal film is discontinuous, the metal particles being present in the form of islands with intervening zones of polymeric material. The resulting composite films have negative temperature coefficient of resistance. The process may be applied to the production of semiconductor composite films, e.g., copper oxide films by means of an annealing oxidative treatment to convert metal to metal oxide before loss of polymeric matrix by oxidation or evaporation.