A valve (30) for controlling a flow of fluid, the valve having a conduit, first valve portion having an inlet, a first humidifier interface, and a first conduit opening to the conduit. The first valve portion defines a switchable flow path between the inlet and either the first humidifier interface or the first conduit opening. A second valve portion has an outlet, a second humidifier interface, and a second conduit opening to the conduit. The second valve portion defines a switchable flow path between the outlet and either the second humidifier interface or the second conduit opening. Responsive to the first and/or second humidifier interfaces being connected to a humidifier chamber, the fluid flows from the inlet to the outlet through the humidifier chamber, and responsive to the first and second humidifier interfaces being disconnected from the humidifier chamber, the fluid flows from the inlet to the outlet through the conduit.
