Abstract: A humidifier is described for use in combination with a hot air forced heating system. The humidifier consists of a main housing (water box) which maintains a constant water level from a existing water source sand controlled by a float control valve. The water is heated by a hot water heating coil. Hot air is directed into, through, and back into the main hot air stream. During this process, the hot dry air picks up moisture, becoming saturated, which is returned and mixed in the hot air supply duct, providing humidity throughout the entire system. The amount of air and humidity can be controlled by the inlet dampers, which regulates the amount of air flowing through the humidifier.