A heat recovery device comprising a gas diverter valve and a gas/liquid heat exchanger; the gas diverter valve comprising a valve body; a valve element movable between a bypass position and a heat exchange position; and a gas inlet and a gas outlet formed in the valve body; wherein a bypass gas flow path extends between the gas inlet and the gas outlet of the valve body and the heat exchanger is located outside the bypass gas flow path; wherein, with the valve element in the bypass position, the bypass gas flow path is substantially completely open and flow communication between the gas inlet and the heat exchanger is substantially completely blocked by the valve element; and with the valve element in the heat exchange position, the bypass gas flow path is substantially completely blocked by the valve element, and the gas inlet is in flow communication with the heat exchanger; characterized in that: the gas/liquid heat exchanger comprises a heat exchanger core comprised of a stack of core plates, the core comprising a plurality of gas flow passages and a plurality of liquid flow passages arranged in alternating order, a gas inlet manifold and a gas outlet manifold in flow communication with said plurality of gas flow passages, and a liquid inlet manifold and a liquid outlet manifold in flow communication with said plurality of liquid flow passages; in that each of the core plates has a gas side and a liquid side, and wherein the core plates are sealed together in the core such that each of the gas flow passages is defined between the gas sides of two adjacent core plates and each of the liquid flow passages is defined between the liquid sides of two adjacent core plates, and such that the manifold openings in the plates align to form said manifolds, with the gas inlet and outlet manifolds in flow communication with the gas flow passages and the liquid inlet and outlet manifolds in flow communication with the liquid flow passages; wherein a bottom of said core is proximate to the valve body and a top of said core is distal to the valve body, and wherein the core includes a bottom core plate located at the bottom of the core; wherein the bottom core plate includes one of said gas inlet manifold openings and one of said gas outlet manifold openings; wherein a bottom-most gas flow passage is defined between the bottom plate and an adjacent one of said core plates; wherein said bottom-most gas flow passage is in direct heat exchange contact with only one of said liquid flow passages; and wherein the bottom plate forms a closed bottom of the liquid inlet manifold and a closed bottom of the liquid outlet manifold. the gas/liquid heat exchanger comprises a heat exchanger core comprised of a stack of core plates, the core comprising a plurality of gas flow passages and a plurality of liquid flow passages arranged in alternating order, a gas inlet manifold and a gas outlet manifold in flow communication with said plurality of gas flow passages, and a liquid inlet manifold and a liquid outlet manifold in flow communication with said plurality of liquid flow passages; in that each of the core plates has a gas side and a liquid side, and wherein the core plates are sealed together in the core such that each of the gas flow passages is defined between the gas sides of two adjacent core plates and each of the liquid flow passages is defined between the liquid sides of two adjacent core plates, and such that the manifold openings in the plates align to form said manifolds, with the gas inlet and outlet manifolds in flow communication with the gas flow passages and the liquid inlet and outlet manifolds in flow communication with the liquid flow passages; wherein a bottom of said core is proximate to the valve body and a top of said core is distal to the valve body, and wherein the core includes a bottom core plate located at the bottom of the core; wherein the bottom core plate includes one of said gas inlet manifold openings and one of said gas outlet manifold openings; wherein a bottom-most gas flow passage is defined between the bottom plate and an adjacent one of said core plates; wherein said bottom-most gas flow passage is in direct heat exchange contact with only one of said liquid flow passages; and wherein the bottom plate forms a closed bottom of the liquid inlet manifold and a closed bottom of the liquid outlet manifold.