Abstract: A steam boiler includes a boiler housing. A helical coil for boiling water and superheating the wet steam is disposed within the boiler housing. A burner emits combustion gases which heat a heat emitter which is disposed in the inner space of the helical coil. Combustion gases from the burner enter the internal cavity of the heat emitter and then pass through perforations in the heat emitter before contacting the helical coil. As such, the heat emitter is heated by the combustion gases and serves as a radiant heat source for the helical coil.