Cooling: How does it work?

Cooling - to remove heat from the food

A refrigerator does not produce cold but removes heat. An effective means of getting rid of this heat is critical for the refrigerator's performance and energy consumption. Isotherm refrigeration systems use either air or sea water to remove heat.

Isotherm Self-Pumping System

The Isotherm SP system is a totally new technique that is cooled directly by the surrounding water. This means that refrigeration efficiency is completely independent of the air temperature inside the boat. Even on the hottest days of summer - just when a refrigerator is needed most - the water-cooled Isotherm SP operates consistently at an extremely high level of efficiency impervious to hot ambient temperatures. Without fans or pumps to remove the heat generated by the refrigeration compressor, the SP system consumes much less battery power and is remarkably quiet. Although heat always rises if left to the laws of nature, the Isotherm SP unit uses the natural movement of the hull to draw heat down and out through a special fitting in the galley sink drain hose.  

 

As this hose is not restricted by pumps or non-return valves, the flow inside is completely free. Each movement of the water surrounding the boat produces a similar change of the water level inside the hose resulting in the pumping of a similar quantity of water in and out through the hull fitting. By designing a special hull fitting containing a non-restricting, full-flow spiral heat exchanger for cooling the heated refrigeration agent, an extremely efficient cooling system is created. As the hull fitting is always situated some distance from the boat's centre of gravity, even the smallest movement of the hull or mast of a sailing boat is sufficient to create a pumping action. This movement by which warm water is continuously pumped out and cold water in, also prevents fouling. The through-hull fitting is made of saltwater resistant brass and the full-flow coil heat exchanger is of copper-nickel alloy. A zinc anode comes with the kit. The 5 ft. pipe connecting it to the compressor and the 8-9.75 ft. pipe from the holding plate are both pre-filled and fitted with quick-fit connectors.