Abstract: A rotary regenerative heat exchanger (2) for transferring heat from a hot fluid to a cold fluid by means of an assembly (30) of heat transfer element which is alternately contacted with the hot and cold fluid. The heat transfer element assembly (30) is comprised of a plurality of first and second heat absorbent plates (32,34) stacked alternately in spaced relationship. The spacing between adjacent first and second plates (32,34) are maintained apart by spacers which comprise bilobed folds (38A and 38B) crimped in the first plates (32) and second plates (34), respectively. The pitch of the folds (38B) is opposite to that of the folds (38A) to prevent nesting between adjacent plates.