Cooling: How does it work?
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 - Three possible cooling systems
Indel Webasto Marine provides different solutions for best cooling performances, to suit every demand. For efficient heat removal, various methods can be applied. Isotherm cooling systems use air or sea water to eliminate heat.
Using air which is blown through the condenser by a fan is the traditional way to remove heat. It is important that the compressor compartment is well ventilated allowing cold air to enter from below and hot air to escape to the top.
Magnum Seawater-Cooled Electric Pump
Isotherm Magnum cooling systems are especially designed for vessels with high refrigeration requirements, for example sailing in tropical waters. Isotherm Magnum uses the surrounding water to increase cooling efficiency. All Magnum models are fitted with integral seawater pumps for circulating cooling water through the cooling section of the refrigerator compressor. The pump is quiet, self-priming, it withstands dry running and it's self-aerating. The highly efficient heat exchanger is manufactured in a corrosion-resistant copper-nickel alloy and fitted with a zinc anode. Seawater-cooled units are extremely efficient and offer increased cooling capacity.
Self-Pumping (SP) Seawater-Cooled
Isotherm SP systems cool with the use of surrounding water. This means that refrigeration efficiency is completely independent from the air temperature inside the boat. Even on the hottest summer days, just when a refrigerator is needed most, water-cooled Isotherm SP operates consistently at an extremely high level of efficiency. With no fans nor 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 nor 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 is fitted as standard.