A respiration humidifier comprising: a base unit; a chamber constructed and arranged to hold a reservoir of liquid; a radiation signal transmitter carried by the chamber and operatively associated with a sensor (16A, 16B) carried by the chamber, the transmitter arranged to wirelessly send a radiation signal indicative of a condition sensed by the sensor; a radiation signal receiver carried by the base unit and arranged to receive the radiation signal from the transmitter; and a control unit that controls the condition based at least in part on the radiation signal received by the radiation signal receiver, characterized in that - the chamber is a detachable chamber; - the sensor (16A,16B) is operatively configured to sense a condition within the chamber, wherein the sensor (16A,16B) is a temperature sensor separate from the transmitter and operatively connected at a distance to the radiation signal transmitter via a connector (17, 217); - the condition is a temperature of the liquid or a humidity of gas in the chamber; and - the transmitter is arranged to be contactlessly powered by the receiver when the chamber is attached to the base unit and the transmitter is in a predetermined range from the receiver and to be powered off when the chamber is detached from the base unit and the transmitter is out of the range. a base unit; a chamber constructed and arranged to hold a reservoir of liquid; a radiation signal transmitter carried by the chamber and operatively associated with a sensor (16A, 16B) carried by the chamber, the transmitter arranged to wirelessly send a radiation signal indicative of a condition sensed by the sensor; a radiation signal receiver carried by the base unit and arranged to receive the radiation signal from the transmitter; and a control unit that controls the condition based at least in part on the radiation signal received by the radiation signal receiver, characterized in that - the chamber is a detachable chamber; - the sensor (16A,16B) is operatively configured to sense a condition within the chamber, wherein the sensor (16A,16B) is a temperature sensor separate from the transmitter and operatively connected at a distance to the radiation signal transmitter via a connector (17, 217); - the condition is a temperature of the liquid or a humidity of gas in the chamber; and - the transmitter is arranged to be contactlessly powered by the receiver when the chamber is attached to the base unit and the transmitter is in a predetermined range from the receiver and to be powered off when the chamber is detached from the base unit and the transmitter is out of the range. - the chamber is a detachable chamber; - the sensor (16A,16B) is operatively configured to sense a condition within the chamber, wherein the sensor (16A,16B) is a temperature sensor separate from the transmitter and operatively connected at a distance to the radiation signal transmitter via a connector (17, 217); - the condition is a temperature of the liquid or a humidity of gas in the chamber; and - the transmitter is arranged to be contactlessly powered by the receiver when the chamber is attached to the base unit and the transmitter is in a predetermined range from the receiver and to be powered off when the chamber is detached from the base unit and the transmitter is out of the range.