The present device concerns a boiler for use in a machine for making hot beverages including a diffuser (32) with a first wall (33) destined to be placed in contact with the liquid to be heated and a second wall (34) opposite first wall (33), heating element (11) consisting of at least one thick film or photo-etching resistor (31) arranged on second wall (34) of diffuser (32), a body which, with first wall (33) of diffuser (32), defines a heating volume (11) inside which the liquid is to be heated, characterized in that it is arranged so that heating volume (11) is positioned on either side of heating element (30). Also described is the fabrication of machines for preparing hot beverages such as coffee.