A rotary regenerative heat exchanger includes a rotor having primary vanes 14 extending between the hub and the periphery of the rotor, and additional secondary vanes 15 between said primary vanes and extending over an outer annulus of the rotor. Such an arrangement facilitates having several of the primary and secondary vanes sealed with respect to a sector plate over the outer annulus as compared with the number of primary vanes sealing with the same sector plate over the inner annulus.