A heat exchanger includes a container having an outlet and an entrance coupled to an inlet and an exit, a receptacle having an entering port and a discharging port for circulating a fluid medium and having an entering opening and a discharging opening. A casing is disposed between the container and the receptacle and includes a passage coupled between the outlet of the container and the entering opening of the receptacle, to allow a heat medium to flow from the container into the receptacle, and a chamber communicating with the discharging opening of the receptacle and the entrance of the container. An air filtering device may be disposed in the casing for air filtering purposes, and for collecting and discharging water.