A rotary heat exchanger through which a first fluid flow—an outside air or inlet air flow, for example—and a second fluid flow—an exit air or outgoing air flow, for example—can flow in a counterflow configuration, has a rotatably mounted rotor (5) that has a first flow sector for the first fluid flow and a second flow sector for the second fluid flow through which the rotor (5) passes during a rotation, a frame in which the rotor (5) is rotatably supported, and a sealing assembly (9) by means of which an inflow side of the first fluid flow and an outflow side of the second fluid flow can be separated from the outflow side of the first fluid flow and from an inflow side of the second fluid flow, respectively. In order to simplify the sealing assembly, with the aim being that a reliable seal between the inflow and outflow sides of the two fluid flows be automatically ensured during operation of the rotary heat exchanger, it is proposed that the sealing assembly (9) have a first seal (12) that bears sealingly against the side of a partition (10) directed upstream into the first fluid flow (2), and a second seal (13) that bears sealingly against the side of the same partition (10) directed upstream into the second fluid flow (3).