A falling film evaporator for a heating ventilation and air conditioning (HVAC) system comprising: an evaporator housing; a plurality of evaporator tubes disposed in the evaporator housing and arranged into one tube bundle, through which a volume of thermal energy transfer medium is flowed; a refrigerant pool zone arranged in a lower portion of the evaporator housing and including a pool tube bundle that circulates a fluid through a pool of refrigerant; a plurality of tube sheets supportive of the pool tube bundle; a first wall member and a second wall member extending vertically at opposite lateral sides of the plurality of evaporator tubes, the first wall member and the second wall member defining an inner vapor passage therebetween, defining a first outer vapor passage between the first wall member and the evaporator housing, and defining a second outer vapor passage between the second wall member and the evaporator housing; a vapor outlet located at a side portion of the evaporator housing, wherein a first distance from the first wall member to the vapor outlet is greater than a second distance from the second wall member to the vapor outlet; wherein a first gap between a first wall member lower edge and the respective tube sheet of the pool tube bundle is greater than a second gap between a second wall member lower edge and the respective tube sheet of the pool tube bundle, in order to bias the flow of vapor refrigerant exiting the inner vapor passage into the first outer vapor passage, furthest from the vapor outlet resulting in a longer path for vapor refrigerant flow to reach the vapor outlet, thereby decreasing the amount of entrained liquid refrigerant mixed with the vapor refrigerant. an evaporator housing; a plurality of evaporator tubes disposed in the evaporator housing and arranged into one tube bundle, through which a volume of thermal energy transfer medium is flowed; a refrigerant pool zone arranged in a lower portion of the evaporator housing and including a pool tube bundle that circulates a fluid through a pool of refrigerant; a plurality of tube sheets supportive of the pool tube bundle; a first wall member and a second wall member extending vertically at opposite lateral sides of the plurality of evaporator tubes, the first wall member and the second wall member defining an inner vapor passage therebetween, defining a first outer vapor passage between the first wall member and the evaporator housing, and defining a second outer vapor passage between the second wall member and the evaporator housing; a vapor outlet located at a side portion of the evaporator housing, wherein a first distance from the first wall member to the vapor outlet is greater than a second distance from the second wall member to the vapor outlet; wherein a first gap between a first wall member lower edge and the respective tube sheet of the pool tube bundle is greater than a second gap between a second wall member lower edge and the respective tube sheet of the pool tube bundle, in order to bias the flow of vapor refrigerant exiting the inner vapor passage into the first outer vapor passage, furthest from the vapor outlet resulting in a longer path for vapor refrigerant flow to reach the vapor outlet, thereby decreasing the amount of entrained liquid refrigerant mixed with the vapor refrigerant.