A heat exchanger, especially for cooling cracked gas, with a nest of tubes secured between two tube plates (2) and with two terminal chambers (4) adjacent to the tube plates and tapering toward a connector (5). The intake-end chamber accommodates inserts. The inserts consist of rods bent into round or polygonal, concentrically positioned rings (7). The rings are positioned away from the tube plate in alignment with the intake-end connector in an area that essentially equals the connector's cross-section.