A falling film evaporator (12) for a heating ventilation and cooling (HVAC) system includes a housing (52) and a plurality of evaporator tubes (26) positioned at least partially in the housing (52) through which a volume of thermal energy transfer medium is flowed. A distribution system (34) is located in the housing to distribute a flow of liquid refrigerant (20) over the plurality of evaporator tubes (26). The distribution system (34) includes a distribution vessel having a plurality of drip openings (38) to flow the liquid refrigerant onto the plurality of evaporator tubes (26), a feed pipe (42) to flow refrigerant into the distribution box (36), and one or more pressure regulators (58) in the distribution system, thereby regulating the flow of liquid refrigerant.