A system for predicting a leak of a HVAC/Refrigeration system includes a critically charged HVAC/Refrigeration system configured to circulate a refrigerant to cool a space, and processing circuitry. The processing circuitry is configured to obtain the subcooling data from the critically charged HVAC/Refrigeration system. The processing circuitry is configured to predict a leak event by providing the subcooling data as an input to a neural network. The neural network is trained using historical data of one or more subcooling parameters of a plurality of critically charged HVAC/Refrigeration systems. The processing circuitry is configured to operate a display to provide a notification to a technician or a manager regarding the predicted leak event at the critically charged HVAC/Refrigeration system.

A system utilizing cascading heat pump circuits (HPCs) is employed to efficiently transfer heat from low temperature reservoirs to high temperature reservoirs. The system of cascading (e.g., multistage) HPCs include at least two HPCs that are in thermal communication. The first HPC uses a first refrigerant and is configured to raise a first cold operating temperature to a first hot operating temperature. The second HPC uses a second refrigerant and is configured to raise a second cold operating temperature to a second hot operating temperature. The second HPC is in thermal communication with the first HPC through a thermal exchange block, which allows the transfer of heat between the HPCs and causes the first hot temperature to be equilibrated with the second cold temperature. The cascading HPC system also includes a system controller that is configured to optimize the coefficient of performance (COP) of the cascading HPC system.