Heat transfer sheet for rotary regenerative heat exchanger

A stack of heat transfer sheets includes one or more first sheet which includes a first undulating surface formed by first lobes that are parallel to each other and oriented at a first angle. The first sheets include a second undulating surface formed by second lobes that are parallel to each other and oriented at a second angle, different from the first angle. The first sheets include a third undulating surface formed by third lobes extending from one or more ends of the first sheet and terminating at an intermediate point between the end and an opposing end thereof. The third lobes are parallel to each other and parallel to the direction of flow through the stack. The stack includes one or more second sheets defining a plurality of sheet spacing features which engage a portion of the first sheet.