A CPAP device includes a humidifier tub including a heat conducting base plate. The CPAP device also includes a cradle to support the humidifier tub in an operative position. The cradle includes a heater plate in communication with the heat conducting base plate of the humidifier tub in use. The cradle further includes a retaining mechanism to retain the humidifier tub in the cradle. The retaining mechanism is structured to force the base plate into engagement with the heater plate.