Abstract: A hot-gas engine electric heater that is partially disposable in a heat exchange tube of a hot-gas engine and supplies heat to a working fluid in the hot-gas engine wherein the heat exchange tube has a contour. The heater includes a thin and circular-shaped base, at least one conically-shaped and outwardly tapering heating element, and a voltage regulator. The thin and circular-shaped base conforms to the contour of the heat exchange tube and has an outer surface and an inner surface that is conformingly and sealingly abuttable against the heat exchange tube and is disposable externally thereto. The at least one conically-shaped and outwardly tapering heating element is horizontally oriented and extends perpendicularly outwardly from the inner surface of the thin and circular-shaped base and receives a voltage for heating the working fluid and is enterable into the heat exchange tube so as to be non-protruding from the heat exchange tube and eliminate wasted heat.