In one aspect, a steam humidifier is disclosed. The steam humidifier includes a tank for containing water to be heated to generate steam and a water connection manifold that has a manifold chamber in fluid communication with a water supply passage and a water drain passage. The steam humidifier further includes a rotary valve that is configured to control a fluid passage between the tank and the manifold chamber and that is further configured to control the position of one or more locking features. The rotary valve is rotatable between a first locked position and a second unlocked position. In the first locked position, the fluid passage between the tank and the manifold chamber is open and the one or more locking features are engaged with a structure of the steam humidifier. In the second unlocked position, the fluid passage between the tank and the manifold chamber is closed and the one or more locking features are disengaged from the structure of the steam humidifier. Other aspects are disclosed.