Condensing boilers represent the peak of domestic heating technology – benefiting from high energy utilisation, low Emissions , reasonable purchase costs, and well-proven technology. Condensing boilers adjust their heat output according to the heat demand and the outside temperature, and also make use of the heat in the flue gases which, in other systems, is lost to atmosphere. In so doing, water condenses in the Boiler ; the integral heat exchange materials are therefore corrosion-resistant. The Efficiency of such condensing systems has effectively reached the theoretical maximum – optimal use is made of the fuel.