What is the required rough opening when the Air Supply opening is 50 Square Inches and the grill has a free area of 75%?

To determine the required rough opening when the air supply opening is 50 square inches and the grill has a free area of 75%, it is essential to consider how the free area affects the overall opening size needed to allow for sufficient airflow.

The free area percentage indicates how much of the nominal size of a grill or louver actually allows air to pass through. In this case, if the grill has a free area of 75%, only 75% of the nominal area contributes to airflow.

To calculate the required rough opening, you can use the formula:

Required Rough Opening = Air Supply Opening / Free Area Percentage

In this scenario, the air supply opening is 50 square inches, and the free area percentage (as a decimal) is 0.75:

Required Rough Opening = 50 square inches / 0.75 Required Rough Opening = 66.67 square inches (approximately 66.6 square inches)

This calculation shows that to achieve the desired air supply through the grill, which operates at 75% efficiency regarding airflow, the rough opening must be around 66.6 square inches, confirming that this value is indeed the required rough opening.

Selecting the appropriate rough opening is crucial for ensuring that the ventilation system operates