An absorption, heat-transfer system with an operationally interconnected generator, absorber, condenser, and evaporator; at least two separate heat sources for heating the generator; and a controller for controlling the heat sources. The controller, e.g., a programmed microprocessor, receives inputs from the absorption system, the heat sources, and loads and a lookup table and provides outputs to select and control the heat sources and maximize their efficiency. A heat distributor and a heat recover unit enable heat source management and additional energy utilization.