What indicates a failure in the spillage test?

The correct answer highlights that combustion gases venting into the combustion appliance zone (CAZ) after 60 seconds is a clear indication of a failure in the spillage test. This test is critical for ensuring that appliances designed to vent combustion gases outdoors are functioning properly. When these gases enter the CAZ instead of being safely vented, it signifies that there may be an obstruction or a flaw in the venting system which poses a serious safety hazard.

The spillage test is designed to check for proper ventilation and correct operation of the appliance. If combustion gases are detected in the CAZ, this suggests poor airflow or an issue that could lead to the potential buildup of harmful gases like carbon monoxide within the living space. The timing of 60 seconds is significant, as it establishes a standard for evaluating the efficiency of the venting system; any leakage of combustion gases into the CAZ beyond that timeframe indicates a critical failure.

Other options, while they may indicate issues with an appliance, do not specifically pertain to the failure of the spillage test. Excessive heat output doesn't directly relate to venting and could be characteristic of normal appliance operation under certain conditions. An abnormal sound might suggest a malfunction but doesn't confirm issues with gas spillage. Increased humidity