Choosing the Right Evaporator

Choose the Type of Evaporator to Fit Your Configuration

There are 3 evaporator types: Vertical Bin (B), Horizontal (H), or Flat Plate (F)

Flat Plate

The flat plate can be mounted on one wall or bent to conform to the shape of the box.

The flat plate works best for dedicated refrigerators or freezers and takes up the least amount of room. If there are adjoining boxes separated by an insulated barrier, the flat plate can be mounted in the freezer side with the refrigerator temperature controlled by a spill-over fan and thermostat. In a single box application, either a vertically mounted bin or a horizontal model gives a freezing section in the enclosed area while keeping the rest of the box at refrigerator temperatures. When planning an all-freezer box or a spill-over system, order a freezer thermostat. When designing the box to be used as either a refrigerator or a freezer, order a dual thermostat.

Stainless steel, brine-filled holding plates are available for special applications.

Vertical or Horizontal Bin

When converting a single box into a refrigerated space, the Vertical Bin or Horizontal (with door) versions make the most sense, as the area inside the bins becomes a freezer to store some frozen goods and make ice. The rest of the ice-box is kept at refrigerator temperatures under the control of the thermostat.

Of the two, the Vertical Bin, available in two sizes, is the most popular in top opening boxes as it is easier to install and use. If the larger size is preferred in a smallish box because of its larger freezer capacity, some of the surface area might have to be covered with an insulating material to ensure goods stay frozen inside. The larger size (340B) is not available in a horizontal configuration with a door, so it would have to be customized to stop goods from falling out when mounted horizontally. The Horizontal version is standard in boxes with front opening doors only. The smallest Horizontal evaporator (130H) is not available as a vertical model, but may be used as such without problems.

Spill-over System

A spill-over system can be used for a large box where more freezer area is required than the largest Vertical or Horizontal models offer. In this application, one area is partitioned off with a barrier, and a Flat evaporator installed that is controlled by a freezer thermostat. A hole is then cut into the barrier and a spill-over fan and thermostat is installed which keeps the rest of the box at refrigerator temperatures. A hole or gap over the barrier provides a return path for the circulating air.

For dedicated refrigerator or freezer boxes, a Flat evaporator may be bent to shape, with an 11/2” minimum radius, and installed around the perimeter of a box.

Choose the appropriate refrigerator or freezer thermostat.

Aluminum Evaporators versus Holding Plates for 12v/24v systems

Holding plates are basically re-freezeable blocks of ice designed to be frozen down with a large, powerful condensing unit run once or twice a day. Although 2 sizes of holding plates are available for the Frigomatic series (12/24v, Danfoss compressor), their use is not recommended by the manufacturer.

Holding plates are less efficient than aluminum evaporators on these systems because the capacity of the compressor for heat removal does not change, but the holding plate must be taken down to a lower temperature, increasing the run time. Although run-time patterns are different, the holding plate requires more running time overall.

Holding plates are heavier, bulkier, less efficient and more expensive than aluminum evaporators. Their use is now restricted to very large boats and charter applications.

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