A communication plate extends along and is sandwiched between cylindrical communication manifolds of a first heat exchanger assembly and a second heat exchanger assembly. The communication plate includes a saddling surface arcuate in one direction and a saddling surface arcuate in the opposite direction for engaging in saddle-like fashion the cylindrical shape of the manifolds. The communication plate defines a plurality of communication plate orifices disposed along the communication plate and aligned co-axial with a plurality of communication orifices disposed along the manifolds to seal the communication orifices of the manifolds and establish distributed and sealed fluid communication between the heat exchanger assemblies.