Ice Machine Evaporators With Separating Grids
If grid separation occurs, it is often more cost-effective to replace the entire ice machine
The evaporators used in commercial ice machines are designed to allow for an efficient transfer of heat energy between the water and the refrigerant. They are also designed to withstand the various temperature changes encountered during the freeze and harvest cycles, as well as a wide range of water conditions. Many evaporators are designed using stainless steel, nickel-plated stainless, or nickel-plated copper for this purpose. These metals provide good heat transfer characteristics and hold up to various conditions. Many manufacturers will also incorporate a grid design to further improve the transfer of heat, allowing heat transfer from five sides as the cubes are formed.
Over time, these grids can separate from the evaporator plate, causing ice to form between the two. When this occurs, the ice slab will not easily drop from the evaporator during harvest. Depending on the degree of separation between the grid and the evaporator plate, this will lead to either long harvest cycles or the ice slab not dropping off the plate. Again, depending on the degree of separation, the ice machine may still produce ice with an extended harvest cycle. If the ice slab does drop off the evaporator, the ice cubes will be slightly melted from the long harvest and will form little “fingers” or “shark teeth,” as some technicians refer to them, on the ends of the cubes. Eventually the problem will worsen and the ice slab will not drop off the evaporator. When this occurs, most ice machines will shut down on a long harvest alarm.
Unfortunately, there is really no method of reattaching the grids back onto the evaporator. Since this is a food area, using any glue, silicon, or cold welding epoxy is not a wise or practical solution. You would not want any of these materials to get into the ice and be ingested. The only real solution is to replace the entire evaporator. Replacing an evaporator is not an easy or inexpensive repair. Most times, it will be more economical to replace the entire ice machine. The only exception to this would be if the evaporator was still covered under the manufacturer’s warranty — then it may be economical to replace the evaporator.
When the customer cannot afford to replace or repair an older ice machine, I have removed the separated grid from the evaporator, explaining to the customer that this is only a temporary fix and that other grids will eventually separate from the evaporator. Many times, this allows the ice machine to continue to operate with some larger-than-normal cubes. This is not a perfect solution, and depending on how many grids have separated and their location, this temporary repair may not work.
It is wise to inspect the grids on these ice machines anytime you experience longer-than-normal harvest cycles. This might save you some diagnostic time by not having to wait for a complete freeze and harvest cycle to see the issue.
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