Frequently asked questions

FAQs concerning Isotherm fridges and Isotemp water heaters


In the following you will find answers to frequently asked questions on our marine comfort solutions:

Isotherm fridges

Isotemp water heaters



Isotherm fridges


1. What are the voltage requirements for Isotherm products?

  • Isotherm AC/DC products work on all power sources used worldwide including 12 and 24 volts DC as well as all AC voltages ranging from 80 to 260 volts including 115 volt and 220 volts both 50 and 60 Hertz. 
  • The AC/DC electronic module has both AC and DC input.  For DC connections, be sure to connect the correct positive and negative to the clearly marked terminals. It is very important that cables of correct dimensions be used for the power supply:

Wire Dimension 8 gauge recommended for runs over 10 feet
Wire Dimension 10 gauge for runs of 5 to 10 feet
Wire Dimension 12 gauge for runs up to 5 feet

  • If using old wiring, be sure that there is no corrosion or lose connections. Insufficient power supply is the number one reason a fridge might not run when installing.
  • Use a 20 amp DC breaker so power to the fridge can be turned off at the breaker rather than using the thermostat to turn off the fridge.
  • Remember that the Danfoss electronics are designed to shut off when voltage drops below 11 volts. This will save batteries and allow critical safety systems like bilge pumps to continue working.
  • Isotherm fridges can be purchased as AC/DC, running on all common power sources worldwide or as just DC-only when a boat may not have a generator or the buyer wants more economy.

2. What is the power consumption of the refrigerator?

Each refrigerator, freezer, and refrigeration system has a power consumption figure supplied for comparison purposes.  You can find this information in the Isotherm catalog at the head of each section.  Figures are calculated at a typical temperature in the fridge and typical ambient temperature.  Warmer temperatures will consume slightly more or less depending on conditions. Some figures are supplied on watts used per 24 hours, others show amps used when the unit is running and average hourly amp draw.

For Isotherm Cruise refrigerators we can provide accurate data about energy consumption as with all tests made we know their actual consumption. It 's more difficult to provide a figure for our refrigerating units systems because we do not know the actual size of the compartment in which it will be installed and also the thickness of the insulating material used. The data for a particular volume are therefore calculated with an insulating material of medium quality and thickness. 

Isotherm fridges are built with the highest quality insulating materials, seals, and keep in the cold and minimize compressor run time.


3. Which is the refrigerator more suitable to my needs?

Indel Webasto Marine has a large number of models, front opened, drawers, top-opened, stainless steel doors or customizable door fronts with different door panels. They can be right hinged or left hinged. In order to decide which is the best solution for your need, just measure the space for installation and thanks to the catalogue it will be extremely easy to search for the appropriate product.


4. Which power supplies are available?

The Isotherm refrigerators are available with standard 12V/24V power, on demand with AC / DC (12-24/115-230V).


5. What are the most important considerations when installing a refrigerator?

Ventilation is the key to good refrigeration.  The compressor exchanges the heat removed from the food and beverages with the ambient air.  Poor ventilation will cause the refrigerator to run longer, consume more battery power, and lose efficiency.

Having a path for warm air to rise up and out of the enclosure where the fridge is installed is key to good performance.  30 square inches at the top and the same at the bottom will allow warm air to exit and cool air to enter in a natural convection. This can be achieved with grills or gaps in the furniture.

The weight of the fridge should be supported by the feet.  The flange is designed to hold the fridge in the enclosure, not to support the weight of the fridge.


6. I would like to build a cooling box on my boat, is it possible?

We can provide a set of panels ready to help you building a cooling box. The panels are covered on both sides with 2mm laminated plastic and have an overall thickness of 50mm closed cells foam insulation. They are extremely easy to cut and paste, using a polyurethane or silicone sealant.


7. Which cooling unit model should I choose?

Indel Webasto Marine offers the most efficient refrigeration for boats thanks to special refrigerating units. Several types are available: 

Compact Unit: The classical cooling unit, controlled by the thermostat, uses a Secop compressor to cool the evaporator installed in your refrigerator or freezer compartment. This system uses a condenser cooled by a fan. It is important that the compartment where the compressor is installed is well ventilated so that the cool air arrives at the bottom and warm air is exhausted to the top. 

ASU Unit: The smart fridge that freezes the holding plate when the engine is running. The ASU system (which stands for AUTOMATIC START UP), runs the compressor when the engine is running and there is a considerable amount of electricity to freeze the holding plate, which consequently will maintain the temperature in the cockpit for extremely long periods also when the engine is not in use. 

SP Unit: Isotherm SP (Self - Pumping) is a system directly cooled by sea water, this means that the efficiency of refrigeration is completely independent of the temperature inside the boat. The heat is directed downwards and expelled through the hull of the boat using the natural pumping action of the drain pipe of the galley sink through a heat sink installed on the discharge. This system is extremely quiet as no pumps nor cooling fans are present. 

Magnum Unit: Magnum units are specially designed for boats that require maximum cooling, possibly to extend sailing in tropical waters. This system uses sea water, which is always cooler than the air inside the boat, through an electric water pump, increasing the cooling efficiency power. Sea water cooling system, being static, is absolutely noiseless, it resists even in the absence of water and is self-aerating.


7b. Can I use a new fridges with my old parts like holding plates or keel cooler?

It is not recommended to connect new equipment to old parts.  While the previous holding plate or keel cooler may appear to still be functional, it may have corrosion or moisture issues that would corrupt all new components connected to it.  Older systems may have used older refrigerant like R22 which is no longer allowed by environmental regulations.  The old refrigerants can have a negative reaction when in contact with R134a which is the currently mandated refrigerant.  The reaction between old and new refrigerants may cause a gummy substance which will clog refrigerant lines and risk loss of all investment.

Isotherm makes it easy to select a system that meets your requirements.  Isotherm systems can be selected by the volume of space you wish to refrigerate or freeze and offer a choice of air cooled or SP water cooled or Magnum water cooled.  For example,  The Isotherm Compact SP 2556 will refrigerate a space up to 14.1 cubic feet and freeze a space up to 4.9 cubic feet. 

A new, complete system will be covered by the exclusive Isotherm 5-year limited warranty on the compressor and two years on all other parts.  Parts are not covered by warranty because it cannot be known how they might be used.  If, for example, you put in a new compressor and evaporator only to connect them to an old keel cooler and the system did not work, there would be no warranty.

The benefit of the Isotherm SP thru-hull is that it can replace the keel cooler and have the benefit of being flush with the hull surface as well as having more surface area in the condenser to remove heat from the refrigerant.  For more information and drawings, please visit the SP page on the USA website which has downloads (middle of page) which can help you visualize the installation:

The new Isotherm Intelligent Temperature Control is a digital control that can be used to regulate the speed of the compressor and the temperatures in the fridge:


8. What is the difference in ASU refrigerators and regular refrigerators?

While all Isotherm products are designed to consume a minimum of battery power, ASU products incorporate a small holding plate suspended under the freezer that acts like an artificial block of ice which keeps the compressor from running as often. The ASU technology monitors available amperage and will Automatically Start Up the 3 speed compressor and run it at high speed when there is additional amperage or at slow speed if there is not.


9. Isotherm has so many cabinet style models – what do I need to know when ordering?

Isotherm cabinet style fridges give boat owners a full range of choices for selecting a refrigerator or freezer. Isotherm features four door styles: 

  • CLASSIC (grey door front that can be changed to your own custom panel or to options in white, teak, mahogany, or cherry panels)
  • ELEGANCE (available in 49, 65, 85 and 130 liters sizes, silver door front as standard, options in white, black, teak, wengé and white oak)
  • Stainless Steel (complete stainless steel door, handle and flange) 
  • Glass Line (white, black, grey or blue tempered safety glass) 


Be sure to specify hinges on right or hinges on left. 


10. What should be done if you go on holiday?

As you sail for several days, it is good practice to clean the refrigerator and check you do not have food with a short time sell-by date that could deteriorate and cause bad odours. It is also suggested to set the thermostat to minimum. In this way, while guaranteeing the preservation of frozen food, you also reduce power consumption.


11. How can I get rid of unpleasant odours in my refrigerator?

It is important to keep the inside of the refrigerator clean by washing it with warm water and mild soap and by drying any water/condensation that may be enclountered. In order to prevent damage to the electrical/mechanical components and /or the formation of mould, when shutting off the refrigerator for extended periods of time, it is necessary to wait for the unit to defrost completely and to eliminate any condensation that may have formed, both inside the appliance and in the external water collection tray. The natural defrosting time can vary from a few minutes to several hours. In the wintertime and when the refrigerator is shut off, the door should be left slightly ajar for ventilation. 



12. What are the climate classes?

On all refrigerators it is indicated in which climate class they can work properly: Class SN +10 ° C +32 ° C and Class N between +16 ° C and +32 ° C, Class ST between +18 ° C and +38 ° C Class T between +18 ° C and +43 ° C.


13. What should I consider when installing my new fridge?

  • The weight of the fridge must be supported on the feet of the refrigerator. The flange is designed to hold the fridge in the enclosure
  • Good ventilation is the key to efficient operation and good temperatures. Allow 12 x 12 centimetres at the bottom of the cabinet and another 12 x 12 centimetres at the top to allow warm air to rise up and out of the cabinet while allowing cool air to enter at the bottom
  • Good power with no drop in voltage or amperage

14. How long should I wait before starting a refrigerator that has just been moved?

In order to avoid damage to the cooling circuit, we suggest you waiting about 2 / 3 hours prior to ignition of the product.


15. Why is Isotherm so much better than other refrigerators?

  • Isotherm features molded door shelves that are an integrated part of the door, providing strength and stability for doors
  • Isotherm has cradles and adjustable holders that keep jars and bottles secure and upright
  • Isotherm has a one-piece, polished food-grade plastic interior that helps resist odors
  • Isotherm has positive latching doors that stay shut even in the roughest conditions
  • Isotherm has the highest level of quality and elegance that adds value to every installation




Isotemp water heaters


1. Why should I choose Isotemp water heaters?

Isotemp Slim and Basic water heaters are ranges of water heaters from 15 to 75L volumes, made just for marine use. 

They give you the following advantages: 

  • Robust design 
  • Horizontal or vertical mounting options 
  • Water tank in stainless steel, corrosion resistant 
  • External cylinder in stainless steel 
  • Stable fixing feet in stainless steel, adjustable to 360 degrees for easy installation 
  • Warranty up to 5 years 
  • Extra-long corrugated heating coil for high heat exchange efficiency 
  • Special safety valve 7bar/100psi 
  • Ultra-thick insulation for lowest temperature loss 
  • Electrical plug and play 
  • Immersion heating element, especially designed to heat also the water at the bottom of the tank 
  • NEW Isotemp SPA water heaters are ranges of water heaters in 5 sizes from 15 to 40L capacity, made just for marine use.

    They give you the following advantages:

    • Robust design
    • Horizontal or vertical mounting options
    • Water tank in stainless steel, corrosion resistant
    • External cylinder in high quality polypropylene 
    • Stable fixing feet in stainless steel, adjustable to 360 degrees for easy installation
    • Warranty up to 5 years
    • Extra-long corrugated heating coil for high heat exchange efficiency
    • Special safety valve 6bar
    • Ultra-thick insulation for lowest temperature loss
    • Electrical plug and play
    • Immersion heating element, especially designed to heat also the water at the bottom of the tank
    • Thermostat mixing valve for mixing hot and cold water (optional)

2. I would like to purchase a water heater, which model? Which power supply?

You can choose among several models with different capacities: 15L, 16L SQUARE, 20L, 24L, 25L, 30L, 40L, 50L, 75L. 

Power installed: 115V or 230V 

Immersion heating element available on: 

  • 750W 
  • 1200W 
  • 2000W 

3. Why should I select a water heater with a more powerful heating element?

The higher the power of the heating element, the faster the water will warm up; absorption is higher and therefore the consumption accordingly.


4. Why should I choose a double coil water heater?

A double coil water heater can be connected to an additional heating system as our air-heater and it is therefore the ideal choice for those who want to run a single product with two separate systems. The air-heater is used to heat small rooms or defrost the windows and then the heating power is not very high but it certainly helps to do more things and save energy on board.

Our contact

Indel Webasto Marine USA
3400 Gateway Drive, Unit 107
Pompano Beach, FL - 33069  USA



Visit us at Metstrade 2018!
November 13th - 15th, 2018
Amsterdam NL
Hall 12 / booth 603 / 703