Abstract: A heating cartridge includes a tube that is thermally and electrically conductive, a first end portion thereof is to be embedded within a heat-expandable material of a thermostatic element; a rod which is electrically conductive and extends at least partially inside the tube in a substantially coaxial manner; and a heating resistor comprising a tubular body which comprises an electrically resistant material and radially positioned between a first end portion of the rod and the first end portion of the tube, by forming a cylindrical interface for electrical contact between the rod and the inner surface of the tubular body as well as a cylindrical interface for electrical contact between the tube and the outer surface of the tubular body, the tube and the rod including respectively, opposite their first end portion, second end portions which are respectively adapted to be connected to the poles of an external current source.