A falling film evaporator for a heating ventilation and cooling (HVAC) system comprising: a housing: a plurality of evaporator tubes disposed at least partially in the housing through which a volume of thermal energy transfer medium is flowed; and a distribution system disposed in the housing to distribute a flow of liquid refrigerant over the plurality of evaporator tubes, the distribution system including: a distribution vessel having a plurality of drip openings to flow the liquid refrigerant onto the plurality of evaporator tubes; a feed pipe to flow refrigerant into the distribution vessel; and one or more pressure regulators in the distribution system, thereby regulating the flow of refrigerant, characterized in that the falling film evaporator further comprises a separator disposed upstream of the distribution system to separate vapor refrigerant from liquid refrigerant, thereby outputting a flow of liquid refrigerant to the distribution system, wherein a flow of vapor refrigerant is output from the separator via a suction port in the separator, wherein the pressure regulator in the distribution system comprises: a flow regulator at the suction port to regulate the flow of vapor refrigerant through the suction port; and a sensor operably connected to the flow regulator to detect a liquid refrigerant level in the distribution vessel; wherein the refrigerant level exceeding a threshold results in stoppage of flow of vapor refrigerant through the suction port. a housing: a plurality of evaporator tubes disposed at least partially in the housing through which a volume of thermal energy transfer medium is flowed; and a distribution system disposed in the housing to distribute a flow of liquid refrigerant over the plurality of evaporator tubes, the distribution system including: a distribution vessel having a plurality of drip openings to flow the liquid refrigerant onto the plurality of evaporator tubes; a feed pipe to flow refrigerant into the distribution vessel; and one or more pressure regulators in the distribution system, thereby regulating the flow of refrigerant, characterized in that the falling film evaporator further comprises a plurality of evaporator tubes disposed at least partially in the housing through which a volume of thermal energy transfer medium is flowed; and a distribution system disposed in the housing to distribute a flow of liquid refrigerant over the plurality of evaporator tubes, the distribution system including: a distribution vessel having a plurality of drip openings to flow the liquid refrigerant onto the plurality of evaporator tubes; a feed pipe to flow refrigerant into the distribution vessel; and one or more pressure regulators in the distribution system, thereby regulating the flow of refrigerant, characterized in that the falling film evaporator further comprises a distribution vessel having a plurality of drip openings to flow the liquid refrigerant onto the plurality of evaporator tubes; a feed pipe to flow refrigerant into the distribution vessel; and one or more pressure regulators in the distribution system, thereby regulating the flow of refrigerant, characterized in that the falling film evaporator further comprises a separator disposed upstream of the distribution system to separate vapor refrigerant from liquid refrigerant, thereby outputting a flow of liquid refrigerant to the distribution system, wherein a flow of vapor refrigerant is output from the separator via a suction port in the separator, wherein the pressure regulator in the distribution system comprises: a flow regulator at the suction port to regulate the flow of vapor refrigerant through the suction port; and a sensor operably connected to the flow regulator to detect a liquid refrigerant level in the distribution vessel; a flow regulator at the suction port to regulate the flow of vapor refrigerant through the suction port; and a sensor operably connected to the flow regulator to detect a liquid refrigerant level in the distribution vessel; wherein the refrigerant level exceeding a threshold results in stoppage of flow of vapor refrigerant through the suction port.