A universal heat engine (60, 60E, 60F) for converting energy from a vapor generator to an output section (150, 150F), comprising: a heat engine section (100, 100F) including, a heat engine body defining a heat engine bore (105, 105F) between a first and a second heat engine body end (101, 101F, 102, 102F); a heat engine piston (106, 106E, 106F) located in said heat engine bore (105, 105F) for reciprocal movement; a first heat engine valve assembly (110, 110F) secured to said first end of said heat engine body, wherein a first engine input interconnected with the vapor generator and a first engine output are connected to the first heat engine valve assembly (110, 110F); a second heat engine valve assembly (120, 120F) secured to said second end of said heat engine body, wherein a second engine input interconnected with the vapor generator and a second engine output are connected to the second heat engine valve assembly (120, 120F); a control (300, 300F) for controlling said first and second heat engine valve assemblies (110, 110F, 120, 120F) for effecting reciprocal motion of said heat engine piston (106, 106E, 106F) within said heat engine bore (105, 105F), characterized in that each of said first and second heat engine valve assemblies (110, 110F, 120, 120F) includes a vapor operated shuttle valve (114, 114F, 124, 124F). a heat engine section (100, 100F) including, a heat engine body defining a heat engine bore (105, 105F) between a first and a second heat engine body end (101, 101F, 102, 102F); a heat engine piston (106, 106E, 106F) located in said heat engine bore (105, 105F) for reciprocal movement; a first heat engine valve assembly (110, 110F) secured to said first end of said heat engine body, wherein a first engine input interconnected with the vapor generator and a first engine output are connected to the first heat engine valve assembly (110, 110F); a second heat engine valve assembly (120, 120F) secured to said second end of said heat engine body, wherein a second engine input interconnected with the vapor generator and a second engine output are connected to the second heat engine valve assembly (120, 120F); a heat engine body defining a heat engine bore (105, 105F) between a first and a second heat engine body end (101, 101F, 102, 102F); a heat engine piston (106, 106E, 106F) located in said heat engine bore (105, 105F) for reciprocal movement; a first heat engine valve assembly (110, 110F) secured to said first end of said heat engine body, wherein a first engine input interconnected with the vapor generator and a first engine output are connected to the first heat engine valve assembly (110, 110F); a second heat engine valve assembly (120, 120F) secured to said second end of said heat engine body, wherein a second engine input interconnected with the vapor generator and a second engine output are connected to the second heat engine valve assembly (120, 120F); a control (300, 300F) for controlling said first and second heat engine valve assemblies (110, 110F, 120, 120F) for effecting reciprocal motion of said heat engine piston (106, 106E, 106F) within said heat engine bore (105, 105F), that each of said first and second heat engine valve assemblies (110, 110F, 120, 120F) includes a vapor operated shuttle valve (114, 114F, 124, 124F).