Evaporator Plates vs Eutectic Plates | Penguin Kuranda
COLD BOX CONVERSION | MARINE REFRIGERATION
Evaporator plate or
eutectic plate?
Both systems cool a marine cold box, but they deliver cooling differently. For most modern conversions, an evaporator plate with a matched compressor and thermostat is the more practical choice.
Evaporator plates vs eutectic plates
An evaporator plate cools the box directly as refrigerant passes through it. A thermostat controls the compressor, switching it on when cooling is needed and off when the set temperature is reached.
A eutectic, or holding, plate stores cooling. The compressor runs long enough to freeze the fluid inside the plate; the plate then releases that stored cooling after the compressor stops.
That difference affects how the system runs, how it is controlled and how it suits a cold box conversion. The comparison below focuses on the plate, not the way the condenser is cooled.
How each plate works
Evaporator plate
Refrigerant circulates through channels in the plate inside the box. A thermostat probe monitors the plate and signals the compressor to start or stop. The compressor runs as cooling is required.
Eutectic holding plate
The refrigeration system freezes the fluid in the plate during a charging cycle. The compressor then stops while the plate releases its stored cooling into the box.
Temperature control
An evaporator system uses a thermostat to cycle the compressor around the selected setting. A holding plate works through a freeze-and-release cycle, so the box temperature moves through a wider range between charging periods.
The supplied draft gives typical temperature variations of ±2°C for an evaporator system and ±6°C for a eutectic plate. These figures are shown below as an illustrative comparison, not as a measured temperature trace for a particular installation.
±2°C
Typical evaporator variation stated in the supplied draft
±6°C
Typical eutectic variation stated in the supplied draft
Illustrative temperature cycles based on the figures in the supplied draft. The graph is not to scale and does not represent a specific installation.
What the difference means for your system
A thermostatically controlled evaporator plate suits a system that cools the box as needed. The plate, compressor and thermostat need to be selected together, and the plate must be sized for the cabinet.
A eutectic system needs a sufficiently long run to freeze its holding plate. That operating pattern was suited to some older installations using engine-driven compressors. A compact DC compressor should not be assumed to be a direct replacement for the compressor in an existing holding-plate system; check the complete system design.
Penguin’s support guidance recommends an evaporator-plate system as a replacement route for older holding-plate systems. The conversion still needs the correct plate, compatible compressor connections and thermostat for the box.
Plate comparison
| Consideration | Evaporator plate | Eutectic holding plate |
|---|---|---|
| Cooling method | Refrigerant flows through the plate to cool the cabinet. | The plate is frozen first, then releases stored cooling. |
| Compressor cycle | The thermostat switches the compressor on and off as required. | The compressor runs to freeze the plate, then stops during the holding period. |
| Temperature control | Thermostatically controlled around the chosen setting. | Temperature follows the plate’s freeze-and-release cycle. |
| Compressor matching | Select a compatible compressor or condensing set, plate and thermostat. | Check that the compressor and plate are designed to work together through the full freezing cycle. |
| Conversion use | Penguin’s recommended replacement option for many older holding-plate systems. | May be retained in an existing installation if the system is suitable and working correctly. |
Our recommendation
For most cold box conversions, use a correctly sized evaporator plate with a compatible condensing set and thermostat. Don’t match a replacement compressor to an old holding plate without checking the full system.
Choosing the plate and condenser cooler
Start with the cold box, then choose the refrigeration equipment to suit it.
- Measure the cabinet. Record the internal dimensions and calculate its volume. Confirm whether it will be used as a fridge, freezer or both.
- Choose the plate type and size. A fridge needs a plate sized to cool the cabinet without freezing its contents. For a freezer, use the largest suitable plate for the cabinet volume. A box evaporator can provide a freezer compartment inside a fridge box.
- Match the plate to the layout. In the Frigoboat range, Series H is intended for cool boxes needing a small freezer compartment; Series B suits larger installations with a freezer compartment; Series F is for larger fridge installations or maximising freezer space. Flat plates can be bent to suit some layouts.
- Select the condensing set and cooling type. Choose the required capacity for the cabinet and consider where you plan to cruise. Air cooling is cheaper to buy and easier to install, but less efficient than water cooling. Pump water cooling dissipates heat more effectively than air cooling. Keel cooling is more efficient, reliable and quieter than pump water cooling, with the compressor as the only moving part.
Penguin’s system guidance suggests air cooling for Northern European cruising and water cooling for Mediterranean or tropical cruising. Check that the evaporator, condensing set, couplings and thermostat are compatible before ordering.
Measure the box before selecting the plate and condensing set.
Check the box before converting
Plate selection is only part of the conversion. Thin or damp insulation, a poor lid seal and unsealed pipe entries all add heat to the box and increase the refrigeration load. Check these before deciding that you need a larger compressor.
Send us your cold box dimensions and intended use, and we can help match the plate and condensing set.
Talk to our teamAbout Penguin
Penguin Refrigeration is a specialist supplier of high efficiency refrigeration and air conditioning products and systems to the recreational vehicle and marine markets. The recent acquisition of Kuranda UK adds highly efficient, clean-burning, quiet combustion diesel heating and cooking products for marine and vehicle use to the company’s portfolio. This positions the company is therefore perfectly equipped to tackle the challenges of sustainable off-grid living. As the exclusive distributor for Vitrifrigo, Veco, Wallas, Kabola, Flostream, Penguin represents the companies that are leading the field in their respective areas; Vitrifrigo’s premium quality, Italian produced, DC fridges and freezers are industry-leading for efficiency. With an unrivalled reputation for reliability and aftermarket support provided by Penguin in the UK and Ireland, Vitrifrigo products are the number one choice for quality van conversions and those looking for true off-grid capability with solar power including the growing overlander and expedition sector. With more than 50 years’ experience in marine refrigeration and air conditioning, Veco delivers some of the industry’s best solutions, blending quality, flexibility and efficiency. Incorporating the Frigoboat and Climma brands, Veco’s comprehensive refrigeration range includes both DC and AC models, catering to everything from small refrigeration systems to walk-in cold rooms for the superyacht sector. In addition, Veco offers standard and custom stainless-steel cabinets, tailored to the marine environment, wine cellars, and fully bespoke cold storage options. Veco’s systems are found on vessels built by some of the most renowned shipyards in the world, a testament to the trust placed in Veco’s expertise in marine climate control. Manufacturing in Finland, Wallas is the de facto industry leader in ultra-low emission diesel combustion technology for off-grid heating and cooking. Using high-grade aluminum and other corrosion-resistant materials. Wallas’s products offer unrivalled durability and reliability operating the harshest marine and polar environments. Kabola is a modern manufacturer of oil and diesel-fired central heating boilers, combi-boilers and combination boiler central heating systems rated for continuous use on boats including liveaboards, trucks, businesses and homes. Kabola’s boilers run on diesel, home heating oil, and even the newest eco-fuels. Through continuous innovation and reputation for longevity and reliability, Kabola is the market leader in this space. The latest technology means the oil-fired central-heating systems are now also clean, economic, silent and compact Kabola central-heating systems can be continuously used in marine and vehicle applications.