A respiratory humidification system comprising: a heater base comprising at least a chamber and a heat source, the chamber including an inlet and an outlet, the heat source configured to heat a liquid to humidify a flow of gases provided by the gases source and flowing from the inlet to the outlet of the chamber; one or more sensors positioned at or near the chamber inlet and/or outlet and configured to monitor parameters of the flow of gases when the respiratory humidification system is in a first operating mode ; a hardware and/or software controller in electrical communication with the one or more sensors, the hardware and/or software controller configured to: detect one or more unusual flow conditions or flow anomalies using the monitored parameters when the humidification system is in the first operating mode ; upon detection of the one or more unusual flow conditions or flow anomalies, change the operating mode of the humidification system from the first operating mode to at least one second operating mode to determine a cause of the one or more unusual flow conditions or flow anomalies; and determine whether the one or more unusual flow conditions or flow anomalies detected in the first operating mode correspond to the flow of gases being reverse to a normal flow of gases under normal operating circumstances of the first operating mode by performing one or more tests in the at least one second mode using parameters monitored when the humidification system operates in the at least second operating mode . a heater base comprising at least a chamber and a heat source, the chamber including an inlet and an outlet, the heat source configured to heat a liquid to humidify a flow of gases provided by the gases source and flowing from the inlet to the outlet of the chamber; one or more sensors positioned at or near the chamber inlet and/or outlet and configured to monitor parameters of the flow of gases when the respiratory humidification system is in a first operating mode ; a hardware and/or software controller in electrical communication with the one or more sensors, the hardware and/or software controller configured to: detect one or more unusual flow conditions or flow anomalies using the monitored parameters when the humidification system is in the first operating mode ; upon detection of the one or more unusual flow conditions or flow anomalies, change the operating mode of the humidification system from the first operating mode to at least one second operating mode to determine a cause of the one or more unusual flow conditions or flow anomalies; and determine whether the one or more unusual flow conditions or flow anomalies detected in the first operating mode correspond to the flow of gases being reverse to a normal flow of gases under normal operating circumstances of the first operating mode by performing one or more tests in the at least one second mode using parameters monitored when the humidification system operates in the at least second operating mode . detect one or more unusual flow conditions or flow anomalies using the monitored parameters when the humidification system is in the first operating mode ; upon detection of the one or more unusual flow conditions or flow anomalies, change the operating mode of the humidification system from the first operating mode to at least one second operating mode to determine a cause of the one or more unusual flow conditions or flow anomalies; and determine whether the one or more unusual flow conditions or flow anomalies detected in the first operating mode correspond to the flow of gases being reverse to a normal flow of gases under normal operating circumstances of the first operating mode by performing one or more tests in the at least one second mode using parameters monitored when the humidification system operates in the at least second operating mode . <EOS>