A heat exchanger assembly, comprising: a frame; a heat exchanger panel mounted to the frame and configured to exchange heat with air flowing therethrough, the heat exchanger panel having a lower end and an upper end, the heat exchanger panel being disposed at an inclined orientation such that the upper and lower ends (26, 24) thereof are offset from one another, the heat exchanger panel comprising: a tubing arrangement for circulating fluid therein; and a plurality of fins in thermal contact with the tubing arrangement, the fins being spaced apart from one another for air to flow therebetween and into an interior space of the heat exchanger assembly; a plurality of enclosing panels (18, 19) connected to the frame and defining in part the interior space of the heat exchanger assembly; a fan assembly disposed vertically above the heat exchanger panel, the fan assembly comprising a fan impeller rotatable about a fan rotation axis to pull air into the interior space of the heat exchanger assembly through the heat exchanger panel and evacuate heated air upwardly from the interior space of the heat exchanger assembly through the fan assembly; characterized by: a sound dampening device disposed within the interior space of the heat exchanger assembly such that air is pulled into the interior space through the heat exchanger panel and then flows through the sound dampening device before being discharged from the heat exchanger assembly via the fan assembly, the sound dampening device comprising: a plurality of baffle members (600 1 -600 5), the baffle members (600 1 -600 5) being spaced apart from one another for allowing air flow therebetween, each of the baffle members (600 1 -600 5) extending at an angle relative to a plane extending through the upper and lower ends (26, 24) of the heat exchanger panel so as to direct air flow upwardly toward the fan assembly. a frame; a heat exchanger panel mounted to the frame and configured to exchange heat with air flowing therethrough, the heat exchanger panel having a lower end and an upper end, the heat exchanger panel being disposed at an inclined orientation such that the upper and lower ends (26, 24) thereof are offset from one another, the heat exchanger panel comprising: a tubing arrangement for circulating fluid therein; and a plurality of fins in thermal contact with the tubing arrangement, the fins being spaced apart from one another for air to flow therebetween and into an interior space of the heat exchanger assembly; a tubing arrangement for circulating fluid therein; and a plurality of fins in thermal contact with the tubing arrangement, the fins being spaced apart from one another for air to flow therebetween and into an interior space of the heat exchanger assembly; a plurality of enclosing panels (18, 19) connected to the frame and defining in part the interior space of the heat exchanger assembly; a fan assembly disposed vertically above the heat exchanger panel, the fan assembly comprising a fan impeller rotatable about a fan rotation axis to pull air into the interior space of the heat exchanger assembly through the heat exchanger panel and evacuate heated air upwardly from the interior space of the heat exchanger assembly through the fan assembly; characterized by: a sound dampening device disposed within the interior space of the heat exchanger assembly such that air is pulled into the interior space through the heat exchanger panel and then flows through the sound dampening device before being discharged from the heat exchanger assembly via the fan assembly, the sound dampening device comprising: a plurality of baffle members (600 1 -600 5), the baffle members (600 1 -600 5) being spaced apart from one another for allowing air flow therebetween, each of the baffle members (600 1 -600 5) extending at an angle relative to a plane extending through the upper and lower ends (26, 24) of the heat exchanger panel so as to direct air flow upwardly toward the fan assembly.