A dual cycle waste heat recovery system includes a high-temperature circuit that utilizes a first working fluid. The first working fluid is heated by a first waste heat source and then expanded through a first expander to produce power. The heat recovery system further includes a low-temperature circuit that utilizes a second working fluid. The low-temperature circuit also includes a first heat exchanger for heating the second working fluid with heat from the first working fluid and a second heat exchanger for heating the second working fluid with heat from a second waste heat source. A control valve selectively controls the flow of the second working fluid to each of the first and second heat exchangers according to a predetermined set of parameters. An expander receives the second working fluid from the first and second heat exchangers and expands the second working fluid to produce power.