Abstract: A baffle assembly is disposed within a manifold of a multi-circuit heat exchanger for dividing the interior volume of that manifold into a first chamber associated with one circuit and a second chamber associated with another circuit. The baffle assembly includes a pair of baffle members that extend generally transversely across the interior volume of the manifold are disposed in spaced apart relationship thereby forming a void space therebetween. The void space is in fluid communication with a region exterior of that manifold whereby any fluid leaking from either of the first or second chamber into the void space will be vented therefrom.