A humidifier includes a tub configured to contain a supply of water and a heater including a first polymer film having an electrically conductive circuit provided upon a surface. The first polymer film is electrically insulating and the tub is formed of molded resin and the heater is molded at least partially within the resin. A respiratory apparatus for delivering a flow of breathable gas to a patient includes the humidifier. A method of humidifying a flow of pressurized breathable gas includes passing the flow of pressurized breathable gas over a supply of water contained in a tub. The tub is formed of molded resin and a heater including a first polymer film having an electrically conductive circuit on a first surface is molded at least partially within the resin.