A humidifier system for heating and humidifying respiratory gases has a
housing with an inner chamber, a first port at the first end for
connection to a ventilator breathing circuit and a second port at the
second end for connection to a patient to supply respiratory gases to the
patient and to receive exhaled gases from the patient. A body of heat
moisture exchange (HME) material is located within the chamber, and a
water permeable device is also located within the chamber. The housing
has a water refill inlet communicating with the water permeable device. A
water supply outside the housing is connected to the water refill inlet
to supply water to the water permeable device. A heater mounted outside
the housing supplies heat to the housing and maintains the housing at a
selected temperature.