Constant temperature and humidity air conditioning unit is an integrated system which maintain requested IAQ as a whole. For precision air conditioning units, they can control the humidity levels and temperature range very precisely. Mainly used for computer rooms and database room. For swimming pool dehumidifier and air conditioner, they can manage the swimming pool humidity, air temperature and even water temperature. For wine cellar climate control systems, they can always maintain the humidity and temperature to a best suitable degree. For passive house ventilating dehumidifier and air conditioners, they are mainly for the energy-efficient construction with good sealing, such as passive house. These constant temperature and humidity control system devices can not only control humidity and temperature but also bring in fresh air and exhaust stale indoor air. What's more, there are air-to-air heat exchanger core inside, thus can preserve most energy from the stale air.