A respiratory apparatus for delivering breathable gas to a patient includes a flow generator that generates a supply of pressurized gas to be delivered to the patient; a humidifier for vaporizing water and delivering water vapor to humidify the gas; a gas flow path leading from the flow generator to the humidifier and from the humidifier to a patient interface; and a heater in thermal contact with the gas and/or the water, wherein the heater includes an elongate heating filament in the form of a tape. A humidifier for respiratory apparatus includes a first respiratory gas passage for receiving gas from a flow generator, a humidifier chamber, a second respiratory gas passage for delivering humidified gas to a patient interface, and a heater in thermal contact with the gas and/or the water, wherein the heater includes an elongate heating filament extending along at least part of both said first and second respiratory gas passages. A conduit for use in a respiratory apparatus for delivering breathable gas to a patient includes a tube; a helical rib on an outer surface of the tube; and a plurality of wires supported by the helical rib in contact with the outer surface of the tube.