SVB price: €907.52
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Excl. VAT, excl. shipping costs.
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Shipping information:
Item no.
Model no.
ISOTHERM - Compact SP 2553
Operating voltage
12 V, 24 V
Evaporator Type
Compressor Type
Shipping information

Product details

The Isotherm SP system is a completely new technology, by means of which the system 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 essential - the water-cooled Isotherm SP operates consistently and efficiently regardless of hot ambient temperatures. Without fans or pumps to remove the heat that is 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, flow 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 salt-water resistant brass and the full-flow coil heat exchanger is made of copper-nickel alloy. A zinc anode comes with the kit. The 1.5 metre pipe connecting it to the compressor and the 2-3 metre pipe from the holding plate are both pre-filled and fitted with quick-fit connectors. Evaporators are available in a variety of shapes and sizes to suit the specific requirements of your icebox design.


  • Seawater cooling for even higher efficiency.
  • Lower power consumption.
  • Silent - no fans or pumps.
  • Heat removed by water means cooler inside the boat.
  • No extra holes in hull required and no protrusions.
  • Easy to install. Replaces the through-hull fitting for galley sink.

SP System includes: a danfoss compressor (BDF35F or BDF50F) with a superior fan-cooled condenser unit, evaporator, hull fitting with heat exchanger, zinc anode, temeperature control unit and click-on bracket.


multi-flag Manual
PDF, 1,23 MB

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Herbert O.
by Herbert O. Flag of Germany 11/21/2016 Verified purchase Variant: 44520
Makes a good impression, but the device is still installed. Communication and service has been first class.

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Customers ask customers

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Your question will be automatically forwarded to other SVB customers and published on the product page. Please do not ask any questions which can only be answered by the SVB team – such as the status of an order or product availability. You are also more than welcome to contact our SVB team by email at: or by phone on: +49 (0)421 57290510 .

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General question

User image of Richard H.
Richard H. asked
on Jan 25, 2020
Flag of English Can this unit be supplied with a flat bendable cooler SP2553. Is it supplied with through hull fitting and thermostat.
User image of Sven W.
Sven W. answered
on Feb 7, 2020
Dear Richard, this package is with the SP2551 cooler. For another complete package, please send us a short inquiry to our: // // and we will make you a quick offer. Your SVB-team.
User image of Jan K.
Jan K. asked
on Aug 19, 2021
Flag of English Hello Do you have available Isotherm cooling system U125X000R11311AA Thank you
User image of Cory V.
Cory V. answered
on Mar 10, 2023
Dear customer, it is a special order please contact us directly.