A refrigeration system comprising: a first circuit including a first heat exchanger, a second heat exchanger, and a pump fluidly connected to the first heat exchanger and the second heat exchanger to circulate a first coolant within the first circuit; a second circuit circulating a fluid, the second circuit including a refrigerated merchandiser (10, 10') defining a product support area and having an evaporator in communication with the product support area to condition the area within a predetermined temperature range; and a third circuit including the second heat exchanger, a chiller unit, and a compressor fluidly connected to the second heat exchanger and the chiller unit to circulate a hydrocarbon refrigerant in heat exchange relationship with the first coolant such that heat from the hydrocarbon refrigerant is absorbed by the first coolant within the second heat exchanger, the chiller unit positioned in communication with the second circuit such that heat from the fluid is transferred to the hydrocarbon refrigerant in the chiller unit; a fourth circuit in heat exchange relationship with each of the second circuit and the third circuit; and a fifth circuit including a condenser, an evaporator, and a compressor arranged in series relationship with each other, wherein the condenser defines a cascade heat exchanger between the first circuit and the fifth circuit, wherein the compressor circulates a hydrocarbon refrigerant in direct heat exchange relationship with the first coolant within the condenser, and wherein the refrigerant charge of the fifth circuit does not exceed approximately 150 grams of hydrocarbon refrigerant, wherein the third circuit defines a micro-chiller refrigerant loop having a refrigerant charge not exceeding approximately 150 grams of refrigerant, wherein the second circuit includes a condenser and the fourth circuit includes the chiller unit and a pump circulating a second fluid through the condenser in direct heat exchange relationship with the fluid of the second circuit to extract heat from the fluid, and wherein the second fluid is further in direct heat exchange relationship with the hydrocarbon refrigerant within the chiller unit to discharge heat to the third circuit. a first circuit including a first heat exchanger, a second heat exchanger, and a pump fluidly connected to the first heat exchanger and the second heat exchanger to circulate a first coolant within the first circuit; a second circuit circulating a fluid, the second circuit including a refrigerated merchandiser (10, 10') defining a product support area and having an evaporator in communication with the product support area to condition the area within a predetermined temperature range; and a third circuit including the second heat exchanger, a chiller unit, and a compressor fluidly connected to the second heat exchanger and the chiller unit to circulate a hydrocarbon refrigerant in heat exchange relationship with the first coolant such that heat from the hydrocarbon refrigerant is absorbed by the first coolant within the second heat exchanger, the chiller unit positioned in communication with the second circuit such that heat from the fluid is transferred to the hydrocarbon refrigerant in the chiller unit; a fourth circuit in heat exchange relationship with each of the second circuit and the third circuit; and a fifth circuit including a condenser, an evaporator, and a compressor arranged in series relationship with each other, wherein the condenser defines a cascade heat exchanger between the first circuit and the fifth circuit, wherein the compressor circulates a hydrocarbon refrigerant in direct heat exchange relationship with the first coolant within the condenser, and wherein the refrigerant charge of the fifth circuit does not exceed approximately 150 grams of hydrocarbon refrigerant, wherein the third circuit defines a micro-chiller refrigerant loop having a refrigerant charge not exceeding approximately 150 grams of refrigerant, wherein the second circuit includes a condenser and the fourth circuit includes the chiller unit and a pump circulating a second fluid through the condenser in direct heat exchange relationship with the fluid of the second circuit to extract heat from the fluid, and wherein the second fluid is further in direct heat exchange relationship with the hydrocarbon refrigerant within the chiller unit to discharge heat to the third circuit.