Abstract: A refrigeration system is disclosed having first stage and second stage compressors, first stage and second stage evaporator coils, and first stage and second stage condenser coils, each connected together to form first stage and second stage closed loop refrigeration circuits. The two circuits are coupled one to the other by a liquid (water, ethylene glycol of other good heat transfer medium) heat transfer loop which interconnects the second stage evaporator and the first stage condenser to transfer heat from the first stage condenser to the second stage evaporator. A plurality of additional refrigeration circuits may be provided, each including a compressor, an evaporator coil and a condenser coil connected together in a closed loop.