Cooled air in cold storage makes pressure to insight. When cold storage performs defrost function, it applies pressure to outside due to the expansion of heated air. This pressure results in cold storage panels and doors are constantly being flexed and damaged over time. Pressure from the pressure equalization valve prevents damage to the cold storage's panels and door. Valves on the pressure release valve open and door under pressure situations, therefore occurrence of an external heat loss.Low wattage heating element is used to prevent freezing of the flap. Pressure balancing valves are made of hygienic plastic.