The time required for an 8HP refrigeration unit to cool a 300-cubic-meter space to 6°C depends on factors like ambient temperature difference, insulation quality, and initial temperature of goods. With an ambient temperature around 30°C and good insulation (e.g., cold storage standards), it takes about 4-6 hours to reach 6°C when empty. If fully loaded with goods at a high initial temperature (e.g., 25°C), it may take 8-12 hours, requiring staged cooling to avoid unit overload. In practice, it’s advisable to pre-cool to 10°C first, stabilize for 1-2 hours, then lower to 6°C. This protects the equipment and ensures uniform temperature. If the ambient temperature exceeds 35°C or insulation is poor, the time may extend by 20%-30%. Check the unit’s operation and space tightness in advance.