Abstract: Support assemblies are described herein for use with heat exchanges, wherein the assemblies are deflector and grid support assemblies having a grid support structure formed of a series of interconnected strips and having a peripheral exterior configured to be positioned within an interior surface of a heat exchanger such that the grid support structure substantially extends across a transverse cross-section of the interior of a the tube heat exchanger, wherein the grid support has a first grid support surface and an opposite second grid support surface longitudinally spaced from the first grid surface, the grid support structure defines a plurality of passageways extending therethrough from the first to the second grid support surface, the passageways being configured to support longitudinally extending tubes of a heat exchanger passing substantially perpendicularly to the first grid support surface through the passageways from the first grid surface to the second grid surface without substantially obstructin