A refrigerant system comprising: a high pressure heat exchanger configured to absorb heat from refrigerant as the refrigerant passes through the high pressure heat exchanger; an economizer module configured to receive a first refrigerant stream and a second refrigerant stream derived from the refrigerant exiting the high pressure heat exchanger; an evaporator configured to evaporate the first refrigerant stream; a first refrigerant line extending from the evaporator and configured to receive the first refrigerant stream; a second refrigerant line extending from the economizer module and configured to receive the second refrigerant stream; characterized by a reciprocating compressor comprising: a main cylinder module having a first inlet connected to the first refrigerant line and configured to receive the first refrigerant stream, direct the first refrigerant stream through the main cylinder module and output the first refrigerant stream from the compressor via a first outlet; and an economizer cylinder module having a second inlet connected to the second refrigerant line and configured to receive the second refrigerant stream, direct the second refrigerant stream through the economizer cylinder module and output the second refrigerant stream from the compressor via a second outlet separate from the first outlet; and a controller for controlling flow of at least one of the first refrigerant stream and the second refrigerant stream; a first valve in the first refrigerant line between the evaporator and the reciprocating compressor, to control flow of the first refrigerant stream into the reciprocating compressor; a second valve in the second refrigerant line between the economizer module and the reciprocating compressor, to control flow of the second refrigerant stream into the reciprocating compressor; a connector refrigerant line between the first refrigerant line and the second refrigerant line and configured to perform at least one of bypassing the first refrigerant stream into the economizer cylinder module and bypassing the second refrigerant stream into the main cylinder module; and a valve in the connector refrigerant line to control at least one of the bypass of the first refrigerant stream into the economizer cylinder module and the bypass of the second refrigerant stream into the main cylinder module; wherein the valve in the connector refrigerant line is located downstream of the valve in the second refrigerant line and upstream of the valve in the first refrigerant line. a high pressure heat exchanger configured to absorb heat from refrigerant as the refrigerant passes through the high pressure heat exchanger; an economizer module configured to receive a first refrigerant stream and a second refrigerant stream derived from the refrigerant exiting the high pressure heat exchanger; an evaporator configured to evaporate the first refrigerant stream; a first refrigerant line extending from the evaporator and configured to receive the first refrigerant stream; a second refrigerant line extending from the economizer module and configured to receive the second refrigerant stream; characterized by a reciprocating compressor comprising: a main cylinder module having a first inlet connected to the first refrigerant line and configured to receive the first refrigerant stream, direct the first refrigerant stream through the main cylinder module and output the first refrigerant stream from the compressor via a first outlet; and an economizer cylinder module having a second inlet connected to the second refrigerant line and configured to receive the second refrigerant stream, direct the second refrigerant stream through the economizer cylinder module and output the second refrigerant stream from the compressor via a second outlet separate from the first outlet; and a main cylinder module having a first inlet connected to the first refrigerant line and configured to receive the first refrigerant stream, direct the first refrigerant stream through the main cylinder module and output the first refrigerant stream from the compressor via a first outlet; and an economizer cylinder module having a second inlet connected to the second refrigerant line and configured to receive the second refrigerant stream, direct the second refrigerant stream through the economizer cylinder module and output the second refrigerant stream from the compressor via a second outlet separate from the first outlet; and a controller for controlling flow of at least one of the first refrigerant stream and the second refrigerant stream; a first valve in the first refrigerant line between the evaporator and the reciprocating compressor, to control flow of the first refrigerant stream into the reciprocating compressor; a second valve in the second refrigerant line between the economizer module and the reciprocating compressor, to control flow of the second refrigerant stream into the reciprocating compressor; a connector refrigerant line between the first refrigerant line and the second refrigerant line and configured to perform at least one of bypassing the first refrigerant stream into the economizer cylinder module and bypassing the second refrigerant stream into the main cylinder module; and a valve in the connector refrigerant line to control at least one of the bypass of the first refrigerant stream into the economizer cylinder module and the bypass of the second refrigerant stream into the main cylinder module; wherein the valve in the connector refrigerant line is located downstream of the valve in the second refrigerant line and upstream of the valve in the first refrigerant line.