Air distribution - Recirculation and air exchange

The air-conditioning of a compartment may work only by treating the air of the room temperature. The majority of the air-conditioners work with recirculation only as the air-conditioner treats and delivers back the same air taken from the room. When handling air (air-conditioning) it is necessary to keep in mind the following rules:

3- Cold air is heavier than warm air and therefore always falls, and for this reason, in order to achieve a good temperature distribution of the air-conditioned space, it is advisable that the treated (cold) air is delivered towards the ceiling, vertically or horizontally. This rule is valid particularly for the spaces of the areas used during the day, such as the wheelhouse;

As these areas suffer the maximum solar effect, it increases the heat load to be dissipated. In order to get a minimum temperature gradient, the air is ideally delivered across the deck head or at least towards the top of the space and therefore takes advantage of the natural convection which pushes the cold air down and lifts the warm air.

3- The winter heating, in a Mediterranean climate, needs less capacity than the summer cooling and it is advisable to give a priority to the configuration for the cooling effect rather than the heating which will be achieved without too much effort.

3- Toilets and the galley space (if apart) are normally not air-conditioned and it is good practice to keep them slightly depressurised by using an exhaust fan; in this way odours will be kept inside these spaces and the exhaust fan will take air from the other rooms which are air-conditioned. External air will be therefore taken from the deck area (saloon), helping the fresh air exchange, and the conditioned air will also cool toilets and the galley.

3- The ducting of the conditioned air must be as simple as possible to reduce a pressure drop; short and straight ducting is the rule, while elbows, bends and generally "winding" paths are to be avoided. Complex "networks" must be avoided as they cause a pressure drop and reduce the air-conditioner's capacity and effectiveness dramatically.

3- All the air-conditioners have a nominal capacity expressed in Btus/h or Watts/h; however this maximum capacity is strictly related to the air treated by the air-conditioner and drop at the same rate as the air flow. Therefore it is recommended that the air circuit is as short and simple as possible, particularly if the maximum capacity of the air-conditioner is needed. The air intake for the air-conditioner is also important. Air intake must be straight back to the air-conditioner through a grill or opening which does not cause any pressure drop.