| Air Conditioning |  | Self-Contained Units |
|
 | Dometic Units from Fischer Panda
The most common type found on boats up to approximately 20m and the most economical. The unit is designed to be installed within the space to be conditioned and as its name suggests, all refrigeration circuitry is self contained on the unit. Compartment cooling is achieved by passing the air over a direct expansion evaporator coil where liquid refrigerant is "boiling off". Temperature control is achieved thermostatically by cycling the compressor on and off according to the thermal load at any given time.
Heating suitable for worldwide operation is by electric elements installed on the unit in the same airflow as the cooling coil.
Heating suitable for warmer climates can be by reverse cycle. This is where the air-conditioning unit acts as a heat pump by reversing the flow of refrigerant through the evaporator and condenser and utilising the latent heat of evaporation of seawater. This is only effective in sea water temperatures >6°C | 
