A heating device is a device used to provide warmth in a space. RADIATOR, with 8 letters, is a type of heating device that uses hot water or steam to heat a room. COIL, with 4 letters, is another type of heating device that uses electricity to generate heat. Etna, with 4 letters, is a type of stove that uses wood or coal to generate heat. LAMP, with 4 letters, is a type of heating device that uses a light bulb to generate heat. OVEN, with 4 letters, is a type of heating device that uses electricity or gas to generate heat.