Heating device (1 a), connectable to a power supply, comprising: a support frame; one or more radiating elements, fixed to said support frame, each radiating element comprising a containment tube capable to operate as an electrode and connectable with said power supply, a longitudinal housing, arranged within said containment tube, a longitudinal electrode, connectable with said power supply and arranged within said longitudinal housing, so as to be isolated from said containment tube, means for generating heat inserted within said containment tube and arranged between, and in contact with, said longitudinal electrode and said containment tube, so that, by applying an electric current between said containment tube and said longitudinal electrode, said heat generating means generate heat, and compression means, adapted to ensure the electrical contact between said longitudinal electrode and said heat generating means and to ensure the electrical and thermal contact between said containment tube and said heat generating means; and one or more dissipation fins capable to dissipate the heat generated by said radiating elements, characterized in that said compression means are housed within said longitudinal housing, interposed between said longitudinal housing and said longitudinal electrode, in that said longitudinal housing is internally provided with lateral reliefs in form of protrusions, and in that said longitudinal electrode comprises laterally a plurality of grooves (33a"), arranged and spaced correspondingly to said protrusions, such that, by exerting a pressure on said compression means by said longitudinal electrode and moving longitudinally said longitudinal electrode with respect to said compression means, said longitudinal electrode arranges below said reliefs, so as to compress and/or preload said compression means. a support frame; one or more radiating elements, fixed to said support frame, each radiating element comprising a containment tube capable to operate as an electrode and connectable with said power supply, a longitudinal housing, arranged within said containment tube, a longitudinal electrode, connectable with said power supply and arranged within said longitudinal housing, so as to be isolated from said containment tube, means for generating heat inserted within said containment tube and arranged between, and in contact with, said longitudinal electrode and said containment tube, so that, by applying an electric current between said containment tube and said longitudinal electrode, said heat generating means generate heat, and compression means, adapted to ensure the electrical contact between said longitudinal electrode and said heat generating means and to ensure the electrical and thermal contact between said containment tube and said heat generating means; and one or more dissipation fins capable to dissipate the heat generated by said radiating elements, characterized in that said compression means are housed within said longitudinal housing, interposed between said longitudinal housing and said longitudinal electrode, in that said longitudinal housing is internally provided with lateral reliefs in form of protrusions, and in that said longitudinal electrode comprises laterally a plurality of grooves (33a"), arranged and spaced correspondingly to said protrusions, such that, by exerting a pressure on said compression means by said longitudinal electrode and moving longitudinally said longitudinal electrode with respect to said compression means, said longitudinal electrode arranges below said reliefs, so as to compress and/or preload said compression means.