Sea Water Cooling of the Air-conditionerAs the heat is rejected overboard by an air-conditioner when cooling, and the consequent problems in a typical marine installation, all marine air-conditioners are water-cooled, in other words the air-conditioner dissipates the heat into the sea water, using a special marine heat exchanger in which the sea water is circulated by means of a pump. Of course a 'land' air-conditioner could also be installed but due to external noise and water ingress the result will hardly be satisfactory. The pump used to circulate the sea water should be rated for continuous duty and built to marine specifications. It normally uses a marine centrifugal pump which is installed below the water line as the standard centrifugal pump is not self-priming. Safety The marine air-conditioning system has two aspects which must be well considered for safety reasons: a) The system is connected to the mains supply and it is essential that the connections follow the safety rules. b) The air-conditioner unit (or its fan coils) must recirculate the cabin air and possibly a small percentage of external air. The air intake should never come from a contaminated compartment or even worse, from the engine or generator room. In case of a problem in the exhaust system of the engine or generator, the exhaust gas is toxic and if the air-conditioner takes and delivers these gasses, it will be extremely dangerous or even lethal to the people on board.
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