🔍 Key Concepts

• Three-way temperature control valve arrangements (diverter vs mixer) in jacket water systems • Where temperature is usually controlled: engine inlet vs engine outlet • Tracing the actual flow path on the drawing around the jacket water cooler and heater

💭 Think About

• On the drawing, follow the arrows from the engine jacket outlet through the cooler and back to the engine. At the 3‑way valve, are two streams being combined into one, or is one stream being split into two? • Look at the sensor/control point: is the system trying to keep the temperature stable going into the engine or coming out of the engine? • Ask yourself: in normal marine practice, which is more critical to control closely for engine life – the temperature entering the engine or leaving it?

✅ Before You Answer

• Identify on the schematic which line is the engine jacket outlet header and which is the engine jacket inlet header • Confirm whether the 3‑way valve has one inlet/two outlets (diverter) or two inlets/one outlet (mixer) by carefully following the flow arrows • Verify which side of the cooler/heater the 3‑way valve is located on and where its controlled outlet ultimately leads (back to engine inlet or away from engine)