A respiration humidifier (10) having a base unit (12) and a chamber (14) constructed to hold liquid (15). A sensor (16a, 16b) is connected to the chamber and configured to sense a condition within the chamber. A radiation signal transmitter (18) is carried by the chamber and associated with the sensor. The transmitter wirelessly sends a radiation signal indicative of the sensed condition. The humidifier includes a radiation signal receiver (20) carried by the base unit for receiving the signal. The humidifier includes a control unit (22) that controls the condition based on the radiation signal received by the radiation signal receiver. Another aspect provides a breathing system (30) using the humidifier. The breathing system includes a gas flow generator (32) that generates a flow of gas to a user circuit coupled to the gas flow generator and adapted to communicate the flow of gas to a user.
