A complete Marine Air air conditioning system requires multiple subsystems, including the control/switch assembly the seawater cooling system, and the air distribution system.
- Controls. Marine Air Systems has two basic types of controls, digital Elite and Passport I/O controls and a mechanical rotary-knob switch assembly:
o The Elite and Passport I/O controls are part of a microprocessor system with many advanced functions, including automatic fan speed control, fault display, and a dehumidification program.
o A rotary-knob switch is a manual control with 2 or 3 knobs to provide mode of operation, thermostat, and variable fan speed control. Reverse-cycle models have automatic changeover between heating and cooling.
- Seawater System. The seawater cooling system consists of an inlet through-hull fitting, seacock (water valve), strainer, pump, and overboard discharge fitting all connected by hose or piping.
If multiple air conditioning units are served by a single seawater pump, then a pump relay and water manifold are required. Marine Air Systems recommends a centrifugal seawater pump for efficient, quiet operation and long life. Centrifugal pumps are not self-priming and must be mounted below the waterline.
It is important that the seawater plumbing be “self draining”, meaning that if the boat is lifted all water in the piping will drain out. An air conditioning system plumbed this way will have no air locks which could disrupt the flow of seawater.
For shallow-draft boats where it is impossible to mount the pump below the water-line, a self-priming pump must be used.
| Fig. 1: Typical Seawater Plumbing System |
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- Air Distribution Systems. Cabin air is drawn into the self-contained unit or air handler through a return-air grille. It is then cooled or warmed and blown back into the cabin through a ducting system. The air should be discharged high in the cabin and away from the return-air grille to ensure good circulation.
Plenums (transition boxes) can be installed in the ducting to allow multiple discharge grilles, in one or more cabins. Insulated duct is recommended to prevent secondary condensation. An air filter, located on the cooling unit or on the return air grille, must be cleaned regularly. Figures 2 and 3 show typical ducting installations.
| Fig. 2 Typical duct installation beneath a settee |
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Fig. 3 Comparison of typical split and self-contained systems |
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