Abstract: A washing system combines a dishwashing assembly and a washable kitchen exhaust hood assembly by means of common use of a sump and pump. The pump selectively communicates with the dishwashing assembly and exhaust hood assembly through a bypass valve or diverting valve assembly having an input and two outputs. An exhaust fan connected by means of a duct system to the exhaust hood assembly is disenabled. The sump is filled with a detergent solution and the pump is activated to distribute the detergent solution within the washable exhaust hood assembly. A control means sequences additional valving to operate through a plurality of wash, rinse, and flush cycles. After the hood wash cycles are completed, the exhaust fan is activated and the bypass valve or diverting valve assembly is selectively activated to cause the pump and sump together with additional controlled valving, to sequence and operate the dishwashing assembly.