COMBUSTION APPARATUS
The invention relates to an apparatus for burning fossil fuel, for instance oil, gas, coal, biogas formed from organic waste, or the like, which apparatus comprises combustion means for burning this fuel in addition to converting means for converting the energy becoming available in this combustion into a desired form of energy, for instance a burner which can transfer the combustion heat to a heat exchanger for heating of heating medium, air or mains water, which apparatus further comprises a supply conduit (8) for combustion air and a discharge conduit (16) for flue gases. In order to increase the efficiency of such an apparatus the apparatus according to the invention has the special feature that the supply conduit for outside air and the discharge conduit for flue gases are mutually communicating via a water vapour exchanging system (18) such that at least a part of the water vapour present in the flue gases is transferred to the incoming combustion air, with the vapour pressure difference between both substance flows as driving force for the water vapour exchange.