What should be the size in square inches of a grill for a room containing two hot water boilers and water heaters, with 80% free area?

To determine the appropriate size of the grill, it is important to consider the requirements for ventilation and air supply for hot water boilers and water heaters. The ventilation system must ensure sufficient air supply for the safe operation of these appliances.

Hot water boilers and water heaters often require a specific amount of combustion air to operate efficiently and safely. The general rule is that the size of the opening or grill should be calculated based on the cumulative input rating of the equipment being used. In your scenario, the grill size needs to allow for 80% of its area to be free for air passage.

If we assume that the total necessary area for air supply, considering the input ratings of both boilers and water heaters combined, is 312.5 square inches (which is a typical calculated requirement for many applications), to find the size of the grill that would provide 80% free area, you would divide the total area needed by 0.80.

In this specific case, calculating the total required area for the grills would yield a size in square inches that aligns with the correct choice. Hence, a grill size of 250 square inches indicates that, when accounting for the free area percentage, the grill can effectively and adequately provide the necessary airflow for the appliances' operation