There is provided a humidifier for a respiratory therapy system that includes a humidification chamber having an inner wall spaced from an outer wall to forma wall cavity between the inner and outer walls. A gas flow path is located within the wall cavity. Gas, such as air, flows along the gas flow path from an inlet to the humidification chamber to an outlet of the humidification chamber. Optionally, the gas flow path may follow a helical route through the wall cavity.
