The invention relates to a heat exchanger element intended for a central heating boiler, which heat exchanger element is designed as a monocasting from substantially aluminum, the heat exchanger element being provided with walls which bound a water-carrying channel, and with at least one wall which bounds at least one flue gas draft to which a burner can be connected, at least one wall which bounds the at least one flue gas draft being water-cooled in that it also forms a boundary of the water-carrying channel, while one said at least one water-cooled wall is provided with heat exchanging surface enlarging pins and/or fins which extend in the respective flue gas draft, wherein the cross-sectional surface of a said pin and/or fin is smaller than 25 mm 2 . The invention also relates to a central heating boiler provided with such a heat exchanger element.