Which two important factors are needed to determine if there is adequate combustion air?

To determine if there is adequate combustion air, it is essential to evaluate the volume of the combustion appliance zone (CAZ) and the input capacity of the HVAC system.

The volume of the CAZ is crucial because it indicates how much air is available for combustion processes. A sufficient volume ensures that appliances can draw in the required air for efficient fuel combustion without depleting the available oxygen in the area.

The input capacity of the HVAC system pertains to how much fuel or energy the equipment utilizes during its operation. It is directly related to the amount of combustion air required—higher capacity systems typically require more air for proper combustion. Evaluating both factors together helps ensure that there is enough air to support safe and efficient operation of HVAC equipment, minimizing the risk of incomplete combustion, which can produce harmful byproducts like carbon monoxide.

While other options mention aspects such as air quality, fuel type, humidity levels, and equipment age, they do not directly address the fundamental requirements for combustion air. Proper combustion relies on the physical space available for air and the fuel consumption needs of the system, making the volume of the CAZ and input capacity the primary metrics for assessing adequate combustion air.