A breathing circuit (21) includes inspiratory and expiratory limbs (22, 24), each having a respective electrically energizable heating circuit (34, 36). The heating circuits (34, 36) are independently and selectively electrically energized through separate power circuits (72, 76) such as to control the temperature in each limb (22, 24) in a desired fashion so as to reduce rainout in the breathing circuit and particularly in the expiratory limb (24).
