Abstract: The present invention is particularly concerned with rotary end face seals of the type including a pair of annular sealing members disposed in relatively rotatable sealing proximity about a rotation axis. Each of these annular members typically includes a radially arranged annular sealing surface with these sealing surfaces being in face-to-face sealing proximity with one another during use so as to define a radially arranged annular sealing interface which separates a region of higher pressure from a region of lower fluid pressure. The invention particularly provides an annular heat exchanger which, in use, surrounds the annular sealing members in radially spaced relation thereto to define, within one of the above-noted regions, an annular zone of fluid pressure between the heat exchanger and the sealing members.