A system for delivering respiratory gas to a patient, said system comprising a humidifier which has a heating element and a chamber having an outlet; an inspiratory conduit having a chamber end connectable to the outlet of the humidifier and a patient end connectable to a patient airway device; and a heating member extending through or along at least a portion of the inspiratory conduit; said system being further provided with the combination of: an airway temperature sensor located at a patient airway sensor location within a patient end of the inspiratory conduit to sense airway temperature of respiratory gas; a chamber end temperature sensor located at a chamber sensor location to sense chamber end temperature of respiratory gas within the chamber or within a chamber end of the inspiratory conduit; and a controller having a user interface configured to display a system diagram which includes the humidifier, inspiratory conduit, patient end sensor location, currently sensed airway temperature at the patient airway sensor location, chamber end sensor location, and currently sensed chamber temperature at the chamber sensor location; wherein the controller is configured to be programmed with default setting values for target chamber temperature and a target airway temperature; wherein the controller is further configured to permit a user to manually override the assigned default target chamber temperature setting by manually inputting a target chamber temperature setting that differs from the assigned default target chamber temperature setting but is within a predetermined acceptable setting range and to override the assigned default target airway temperature setting by manually inputting a target airway temperature setting that differs from the assigned default target airway temperature setting but is within a predetermined acceptable setting range; wherein the controller is programmed to control the amount of heat delivered by the heating member so as to cause the sensed airway temperature to be equal to or within a predetermined acceptable variance range of the target airway temperature setting and the sensed chamber temperature to be equal to or within a predetermined acceptable variance range of the target chamber temperature setting. an airway temperature sensor located at a patient airway sensor location within a patient end of the inspiratory conduit to sense airway temperature of respiratory gas; a chamber end temperature sensor located at a chamber sensor location to sense chamber end temperature of respiratory gas within the chamber or within a chamber end of the inspiratory conduit; and a controller having a user interface configured to display a system diagram which includes the humidifier, inspiratory conduit, patient end sensor location, currently sensed airway temperature at the patient airway sensor location, chamber end sensor location, and currently sensed chamber temperature at the chamber sensor location; wherein the controller is configured to be programmed with default setting values for target chamber temperature and a target airway temperature; wherein the controller is further configured to permit a user to manually override the assigned default target chamber temperature setting by manually inputting a target chamber temperature setting that differs from the assigned default target chamber temperature setting but is within a predetermined acceptable setting range and to override the assigned default target airway temperature setting by manually inputting a target airway temperature setting that differs from the assigned default target airway temperature setting but is within a predetermined acceptable setting range; wherein the controller is programmed to control the amount of heat delivered by the heating member so as to cause the sensed airway temperature to be equal to or within a predetermined acceptable variance range of the target airway temperature setting and the sensed chamber temperature to be equal to or within a predetermined acceptable variance range of the target chamber temperature setting.