Heat Exchangers

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Heat Exchangers  There is more than one way to set up a cooling system for your engine. Here is some information about the different methods and how they work. Direct cooling – This is the most basic set up, where water is pumped from the sea or river, it passes through the engine water galleries which transfers the heat from the engine to the water and is then expelled from the engine through the exhaust system. This method doesn’t always allow the engine to get to its optimum working temperature and means the engines will be running colder than it should be, it is also not normally hot enough to heat a calorifier. This method is considered a less satisfactory method of engine cooling. You could also experience problems as the water galleries inside the engine can block up with impurities from the raw water, the engine components are more susceptible to corrosion and you are unable to add anti-freeze into the system to protect the engine over winter. Indirect cooling – This is the most popular method of engine cooling as the raw water (sea water) never comes into contact with the engine components. The engine will have a separate fresh water circulating system which is passed through a heat exchanger. The raw water is also passed through the heat exchanger inside a tubestack which transfers the heat from the fresh water to the raw water and then the raw water is expelled through the exhaust system, this method, although a bit more complicated, gives better temperature control which is regulated by a thermostat allowing the engine to run at is optimum temperature. This type of system allows you to add cooling additives such as antifreeze to the closed circuit and will produce enough heat to heat up a calorifier. Keel cooling - This is more commonly found on narrow boats and works by pumping the engine coolant water around the engine which is then passed through pipes or skin tanks on the bottom of the hull that take the heat from the water which returns to cool the engine again, this is a closed circuit system and the exhaust would more commonly be a dry exhaust on this sort of application, one of the advantages of this system is that there is no external water source that will enter the cooling system and cause blockages. However, some keel cooled applications incorporate a raw water pump that would be used solely to supply the exhaust system with water, the engine coolant will still be contained in the closed circuit.