Patent ID: 6981651
Filing Date: 2006-01-03
Classification: F23J,F24H,F28C,F28D,Y02B,Y02E

Abstract:
1. A heating system for a building comprising a boiler and radiators for heating different regions of the building which are supplied with hot water from the boiler and in which the boiler and radiators are all in the building, wherein the boiler includes a burner for burning a hydrocarbon fuel such as gas or oil in a combustion chamber, and a heat recovery system is provided by which heat which would normally be lost in the hot exhaust gases leaving the combustion chamber is recovered therefrom, wherein the heat recovery system comprises heat exchange means through which water returning from the radiators is caused to flow, and through which water at a temperature below the dew point of the water vapour in the flue gases is also caused to flow to cool the hot gases to recover the latent heat of vaporisation from the water vapour therein, and wherein the heat exchange means includes primary and secondary water circuits, water in the secondary circuit being in direct contact with the hot flue gases so that the condensed water and any water soluble products of combustion can mix with the cooling water and will leave the heat exchange means with the cooling water, characterised by means for diverting a proportion of the water returning to the boiler from the radiators from an exit in the return path to a further heat exchange means located within a region of the building which is maintained at a lower temperature than other regions of the building thereby to cool the diverted water to a temperature below the dew point, means for conveying the cooled diverted water via the primary water circuit in the heat exchange means to re-enter the return water path to the boiler, downstream of the exit point from which it was diverted, to return to the boiler for reheating, and a pump is provided for pumping water in the secondary water circuit from a region in which it is cooled by the cooled diverted water flowing through the primary circuit to an upper region to form a cascade in which the hot gases are mixed therewith.