Abstract: A heat exchanger has a main body coupling with a positioning plate. A condensing device, two filter plates and two fans are disposed in the main body. The main body has a peripheral base plate, a first air exhaust exit and a first fan opening. A blocking wall is disposed transversely in the main body below the first air exhaust exit. The positioning plate has a peripheral flange, a second air exhaust exit, and a second fan opening. The first and second fans are positioned on the first and second fan openings. The first and second filter plates are positioned on the first and second air exhaust exit. The condensing device is disposed in the main body slantwise. Two heat-insulated sponge pads seal two opposite sides of the condensing device.