A warewash machine includes a housing defining a ware inlet, a ware outlet and an internal chamber including a plurality of sequential spray zones including at least one wash zone and a rinse zone downstream of the wash zone in a ware conveyance direction. A vent path leads from the chamber leading to a vent outlet for connecting to a building ventilation system. A damper is provided for controlling a flow area at a location along the vent path. A controller is connected to control a position of the damper, the controller configured to adjust a position of the damper based upon input from at least a first temperature sensor, wherein the first temperature sensor is located at one of (i) the ware inlet, (ii) the ware outlet or (iii) along the vent path. Methods of operating a warewash machine are also provided.