16 www. refrigerationandaircon. co. za RACA Journal I March 2026
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La Grange added that design constraints frequently complicate maintenance:“ In tiny bakery freezers, you sometimes have to remove the entire evaporator to replace a defrost heater. That’ s not poor design – it’ s just the reality of tight spaces.”
THE IMPORTANCE OF AIRFLOW Airflow direction also affects performance. Drawing air through the coil, rather than pushing it, gives smoother, more uniform flow and better heat transfer: just as air-handling units place fans on the discharge side.“ When air is drawn, it passes evenly through the coil instead of swirling around it,” he said.
Air movement must also serve people. In prep areas where staff work in light clothing, comfort matters as much as cooling capacity. A 30m ² space at 15 ° C might require a 1.6kW duty, handled by a single-fan coil – but dual-discharge models can distribute air more evenly, preventing drafts and cold spots.
Humidity adds another dimension. Air entering the coil typically has about 80 % RH( Relative Humidity). Smaller ΔT values risk excessive dehydration of produce; larger ΔT values reduce moisture removal. Balancing ΔT maintains the right humidity for products such as lettuce or blueberries.
REAL-WORLD EXAMPLES For a freezer room at-18 ° C suction-25 ° C using R404A and a 3.05kW duty, redundancy is key. A single-fan evaporator could suffice, but two smaller fans ensure continued operation if one fails – crucial when product loss could be catastrophic.
“ In prep areas where staff work in light clothing, comfort matters as much as cooling capacity.”
Left to right: Marius La Grange and Hennie Basson.
16 www. refrigerationandaircon. co. za RACA Journal I March 2026