Abstract: There is provided a heat exchange unit (1) for recovering heat energy from a hot gas, the heat exchange unit comprising an inlet duct (11) for receiving the hot gas, a heat exchange duct (22) having a heat exchanger (25) for recovering heat from the hot gas, and a bypass duct (24) which bypasses the heat exchange duct and the heat exchanger, wherein the heat exchange unit further comprises a damper (30) configured to apportion the hot gas from the inlet duct (11) between flowing through the heat exchange duct (22) and flowing through the bypass duct (24), wherein the damper (30) is in the shape of a cone, or comprises rotatable shafts with paddles having two sides that converge towards one another to define a taper in the paddle, the taper directed radially away from the shaft.