What is typically required when the worst case test fails in a CAZ assessment?

In a CAZ (Combustion Appliance Zone) assessment, when the worst-case test fails, it indicates that the environment may not be safe for combustion appliances due to potential backdrafting or inadequate ventilation. In such cases, measuring natural pressure differences becomes crucial to understand the dynamics within the zone. By accurately measuring these pressure differences, you can determine if there are negative pressures that might lead to dangerous situations such as drawing carbon monoxide back into the living space from combustion appliances.

This measurement is essential because it helps in assessing the performance of the ventilation system and identifying the necessary corrective actions to ensure safety. The information gained through the pressure measurements allows specialists to devise strategies that may involve improving ventilation or sealing off air pathways to mitigate risks associated with poor appliance operation.