A heat recovery unit comprising: - a heat exchanger formed by a shell (3.3) housing one or more exchange tubes or pipes (3.4) extending in a longitudinal direction X-X', where the tube or the plurality of tubes (3.4) or pipes extend between a first inlet or outlet (3.5) and a second inlet or outlet (3.6) arranged at both ends of the shell (3.3), respectively; and where the inside of the heat exchanger is adapted to allow the circulation of a coolant fluid to remove the heat from the fluid passing through the tube or the plurality of tubes (3.4) or pipes, - an exhaust pipe arranged essentially parallel to the longitudinal direction X-X', - a base formed essentially by a plate, oriented essentially perpendicular to the longitudinal direction X-X', adapted to be coupled and fixed to a support, particularly the support of a catalytic converter or a particle filter, where this base presents at least: - a first perforation suitable for being coinciding with a perforation of the support in its operating position, housing one end of the heat exchanger, - a second perforation suitable for being coinciding with a perforation of the support in its operating position, housing one end of the exhaust pipe, - a manifold in turn comprising: - a first seat (1.1) housing one end of the heat exchanger, i.e., the end opposite to the end housed in the base, - a second seat (1.2) housing one end of the exhaust pipe, i.e., the end opposite to the end housed in the base, - an outlet pipe, - a valve interposed in the exhaust pipe with an outlet in fluid communication with an exhaust line such that the valve has two end positions: - a first end position allowing passage from the catalytic converter or the particle filter to the exhaust line, closing communication between the manifold and the exhaust line for cooling EGR gas; and, - a second end position allowing passage from the manifold to the exhaust line, closing communication between the catalytic converter or the particle filter and the exhaust line for recovering heat by means of the heat exchanger, such that the heat exchanger and the exhaust pipe together with the valve thereof are interposed between the base and the manifold. - a heat exchanger formed by a shell (3.3) housing one or more exchange tubes or pipes (3.4) extending in a longitudinal direction X-X', where the tube or the plurality of tubes (3.4) or pipes extend between a first inlet or outlet (3.5) and a second inlet or outlet (3.6) arranged at both ends of the shell (3.3), respectively; and where the inside of the heat exchanger is adapted to allow the circulation of a coolant fluid to remove the heat from the fluid passing through the tube or the plurality of tubes (3.4) or pipes, - an exhaust pipe arranged essentially parallel to the longitudinal direction X-X', - a base formed essentially by a plate, oriented essentially perpendicular to the longitudinal direction X-X', adapted to be coupled and fixed to a support, particularly the support of a catalytic converter or a particle filter, where this base presents at least: - a first perforation suitable for being coinciding with a perforation of the support in its operating position, housing one end of the heat exchanger, - a second perforation suitable for being coinciding with a perforation of the support in its operating position, housing one end of the exhaust pipe, - a first perforation suitable for being coinciding with a perforation of the support in its operating position, housing one end of the heat exchanger, - a second perforation suitable for being coinciding with a perforation of the support in its operating position, housing one end of the exhaust pipe, - a manifold in turn comprising: - a first seat (1.1) housing one end of the heat exchanger, i.e., the end opposite to the end housed in the base, - a second seat (1.2) housing one end of the exhaust pipe, i.e., the end opposite to the end housed in the base, - an outlet pipe, - a first seat (1.1) housing one end of the heat exchanger, i.e., the end opposite to the end housed in the base, - a second seat (1.2) housing one end of the exhaust pipe, i.e., the end opposite to the end housed in the base, - an outlet pipe, - a valve interposed in the exhaust pipe with an outlet in fluid communication with an exhaust line such that the valve has two end positions: - a first end position allowing passage from the catalytic converter or the particle filter to the exhaust line, closing communication between the manifold and the exhaust line for cooling EGR gas; and, - a second end position allowing passage from the manifold to the exhaust line, closing communication between the catalytic converter or the particle filter and the exhaust line for recovering heat by means of the heat exchanger, - a first end position allowing passage from the catalytic converter or the particle filter to the exhaust line, closing communication between the manifold and the exhaust line for cooling EGR gas; and, - a second end position allowing passage from the manifold to the exhaust line, closing communication between the catalytic converter or the particle filter and the exhaust line for recovering heat by means of the heat exchanger,