A diverter/mixing valve is provided that includes a main outer housing and a barrel assembly disposed inside the main outer housing. When actuated, an actuator rotates the barrel assembly between an open end inlet position where a first fluid stream flows into a first inlet port and a second fluid stream is blocked from flowing into a second inlet port, and an open side inlet position where the second fluid stream flows into the second inlet port and the first fluid stream is blocked from flowing into the first inlet port.