Hangzhou 3King Air-Conditioning Equipment Co.,ltd., is a joint venture,produces air to air heat exchanger.ALH Series product is heat exchanger air processor. The machine takes into the exhaust air and fresh air and makes total heat exchange between each other before they entering the room. Pre-treating the fresh air by energy of the exhaust air can enable the fresh air to lower temperature and reduce humidity in summer and do the opposite in winter, therefore the energy is recycled effectively and the indoor air is kept circulating.