Heat exchange cell comprising: - a containment casing comprising a rear wall, a front wall and a peripheral side wall; - a helically-shaped heat exchanger comprising at least one tubular duct for the flow of a first heat transfer fluid coiled about a longitudinal axis of the helix according to a plurality of coils; said heat exchanger being mounted in said containment casing; - a feeding zone of a second heat transfer fluid, intended for the heat exchange with said first heat transfer fluid, defined in the casing coaxially and internally with respect to said heat exchanger; - a first collection chamber of the second heat transfer fluid externally defined with respect to said heat exchanger between a radially outer wall of the heat exchanger and the peripheral side wall of the containment casing; and - a second collection chamber of the second heat transfer fluid at least partially delimited by at least one separating element mounted at an axially external position with respect to said heat exchanger; wherein the peripheral side wall of the casing encloses and laterally delimits the heat exchanger and the first collection chamber of the second heat transfer fluid substantially along the entire axial extension thereof; wherein said second collection chamber has a substantially annular configuration and is defined at an axially external position with respect to said heat exchanger between said at least one separating element, the peripheral side wall and the rear wall or the front wall of the containment casing; wherein said first and second collection chambers of the second heat transfer fluid are separated from one another by said at least one separating element and are in fluid communication with each other by means of at least one first passage (17a, 17a', 17b-17g; 14e) configured to allow a flow of the second heat transfer fluid from said first to said second collection chamber substantially in parallel to said peripheral side wall and in proximity thereto; wherein said separating element comprises a heat exchange portion in contact with at least one portion of an end coil of the heat exchanger and configured to allow a heat exchange between said at least one coil portion of the heat exchanger and said second collection chamber; and wherein the heat exchange cell further comprises at least one second passage allowing a fluid outlet from the second collection chamber, said second passage being peripherally defined in said second collection chamber between an axial end of the peripheral side wall and the rear wall or the front wall of the containment casing. - a containment casing comprising a rear wall, a front wall and a peripheral side wall; - a helically-shaped heat exchanger comprising at least one tubular duct for the flow of a first heat transfer fluid coiled about a longitudinal axis of the helix according to a plurality of coils; said heat exchanger being mounted in said containment casing; - a feeding zone of a second heat transfer fluid, intended for the heat exchange with said first heat transfer fluid, defined in the casing coaxially and internally with respect to said heat exchanger; - a first collection chamber of the second heat transfer fluid externally defined with respect to said heat exchanger between a radially outer wall of the heat exchanger and the peripheral side wall of the containment casing; and - a second collection chamber of the second heat transfer fluid at least partially delimited by at least one separating element mounted at an axially external position with respect to said heat exchanger;