Method for thermally spraying a heater onto a substrate, comprising providing a metallic material having a core and an insulator therein and thermally spraying the metallic material and the insulator onto a substrate to form a heater. Method of fabricating a thermally sprayed gas heater, comprising providing a gas flow apparatus that propels a gas through a housing; thermally spraying a material to form a resistive heating layer; bonding the resistive heating layer to a surface of the apparatus, the heating layer being positioned to heat the gas flow in the housing. Method of fabricating a heater system of a turbulent gas flow duct, comprising providing a duct having a gas flow channel, the channel having a shaped surface providing a turbulent gas flow therein; thermally spraying a material to form a resistive heating layer; positioning the resistive heating layer to heat the gas flow in the channel.