If an appliance rated over 400,000 BTUH is installed in a Boiler Room with a combustion air opening of 90 Square Inches, what size of ventilation air opening is required?

In determining the required size of ventilation air openings for an appliance rated over 400,000 BTUH installed in a Boiler Room, it is crucial to refer to applicable standards and guidelines regarding combustion air requirements. Appliances with higher BTU ratings, like those over 400,000 BTUH, typically necessitate larger combustion air openings to ensure adequate air supply for safe and efficient operation.

For an appliance of this size, a general guideline is to have a minimum of 1 square inch of combustion air per 1,000 BTUH of input. In this scenario, with an appliance rated at over 400,000 BTUH, the calculation for the required combustion air would suggest a minimum area much larger than the provided opening of 90 square inches. Adequate ventilation is essential to prevent backdrafting and to ensure complete combustion, thus minimizing the risk of hazardous situations.

The correct choice indicates a ventilation air opening of 10 square inches, which aligns with the calculated requirements to support safe combustion and operation of the appliance installed in the Boiler Room. This air opening allows for the necessary air exchange and contributes to maintaining proper airflow, essential for the long-term functioning and safety of the system.