TECHNICAL: AC Specification

Marine Air Conditioning Specification

It is very important that Air Conditining is specified and sized correctly.  Too small and you will not achieve the desired temperature in the cabin, too large and it will not cycle correctly and fail to dehumidify the air.  (air conditioners dehumidify the air as part of the cooling process). 

The key areas to consider are:

1. Calculating the Correct Btu Load for your boat
Construction of the boat - Materials such as aluminum and steel are better conductors of heat than fibreglass or wood.
Level of glazing - a raised deck saloon will have a considerably higher Btu loading than flush deck sailboat.  Wheelhouses and saloons on flybridge power boats also have very high heat loads due to the large number of windows.
Internal heat loads - the galley or engine room will also add considerably to the Btu load on the boat.

2. Intended Cruising Location
If you are planning to cruise in the Tropics or around the Middle East your Btu loads will be higher than if you are looking for comfort cooling while cruising northern European waters.  For simplicity we split locations into three categories; Comfort/Med/Tropical

3. Type and Location of Air Conditioning Units
Stand alone units
are better suited to smaller installations and are much easier if retrofitting AC. 
Chilled Water Systems are ideal for larger installations where there are a large number of areas requiring individual climate control. In Chilled water systems the compressors are mounted in the engine room or engineering space making the system much quiter in operation.
Correct Air Distribution
In both instances it is very important to provide proper air distribution, as direct from the blower as possible with correctly sized delivery and return air grills.  If the grill sizing is too small or the duct is obstructed the AC unit will be 'strangled' with insufficent air flow making it noisy and potentially fail.
Good Water Flow
Similarly it is crucial that the sea water cooling system supplies the correct flow of water to the condensers.  Where possible always fit a scoop, (forward facing) mount the pump as low as possible and keep the pipe runs as direct as possible.

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