Abstract: An expandable modular system including standardized dual heat pump modules that are connectable to other standardized heat pump modules. The modules include pumps for a source fluid and for heat transfer fluid that is circulated to a point of use. The heat pump modules are controlled by a dedicated programmable logic controller. The system may be adapted to transfer heat from a source stream that would otherwise be wasted or not utilized for thermal energy rectification. The modules are of limited size to fit through pedestrian doors and are pre-assembled prior to installation.