An apparatus for delivering breathable gas to a patient includes a flow generator to generate a flow of breathable gas; a humidifier chamber to contain a supply of water; a first flow path to deliver the flow of breathable gas from the flow generator to the humidifier chamber; a second flow path to deliver the flow of breathable gas from the humidifier chamber to a patient interface; and a wicking element and/or a flat, elongate heating element provided at least in the humidifier chamber. A method of delivering a flow of breathable gas to a patient includes generating a flow of breathable gas; and humidifying the flow by passing the flow over a supply of water. Humidifying the flow includes heating the supply of water and/or the flow with a heating element in thermal contact with the water and/or the flow before passing the supply of water, the flow over the supply of water, and/or the flow after passing the supply of water; and controlling a voltage applied to the heating element to control the humidity of the flow. A tube for use in delivering a flow of breathable gas to a patient includes a circuit including electrically conductive ink provided on an inner surface and/or an outer surface.