Patent ID: 7779893

Claim:
A combination heat exchanger comprising of: a heat exchange core having a plurality of tubes, wherein said core has at least one core end; at least one end tank having: two side walls along a longitudinal axis, and two end walls along a latitudinal axis defining an elongated cavity, two bulkheads along said latitudinal axis within said cavity defining a first chamber, a second chamber, and a third chamber, wherein said bulkheads have a height less than height of said two side walls and said two end walls; and a perimeter edge defined by exterior edges of said two side walls and exterior edges of said two end walls; a gasket having an initial diameter, wherein said gasket is fixed on said perimeter edge and exterior edges of said bulkheads; and a header plate mechanically engaged with said end tank compressing said gasket therebetween, wherein said header plate has: a stage portion elevated toward said cavity, said stage portion having latitudinal pockets cooperating with said exterior edges of said bulkheads defining a first spatial distance therebetween; and an annular planar surface cooperating with said perimeter edge defining a second spatial distance therebetween; wherein end tank further comprises at least one foot step extending from a segment of said perimeter edge between said bulkheads in surrogate of a segment of said gasket, wherein said foot step engages a portion of said annular planar surface of header plate providing and maintaining said first spatial distance to be less than said second spatial distance; thereby ensuring a greater compression ratio of said gasket within said first spatial distance as compared to the compression ratio of said gasket within said second spatial distance.