Although it is recommended to use a face velocity of 500 fpm when sizing a return air grille, you can use a 600-800 fpm as well but take note that the noise created by the grille is expected to be higher. Also, if you use a lower face velocity like 300-400 fpm, the grille size will be bigger.

If you really need to use a smaller return air grille, I recommend you don’t exceed 800 fpm of face velocity. Alternatively, you can seek return air grilles with a larger free area. Otherwise, use more than one grille if possible. Earlier, we calculated the grille based for 1050 CFM based on a free area of 70%. Now, what if the actual free area of the grille is 80%? When a return air grille is due for a replacement, you must replace it with an equally-sized one. To appropriately measure a return air grille, always measure the duct opening size and look for a grille that matches it. Return air grilles are typically made in standardized sizes. However, upon request, many grille suppliers do provide custom-made sizes at a higher price.If you’re still a bit confused, you can figure out the amount of players in the game by opening up the leaderboard. This can be done by tapping on the circle with three dots in it button or hitting tab on your keyboard. Once you have the leaderboard open, simply count the number of players that are in your server including yourself. If your server is full at the moment, then there’s 14 players in it because that’s the maximum. Return air grilles are standardized based on 2″ per size increase. The smallest return air grille is usually starts at 4 inches by 4 inches. So, the next corresponding return air grille size includes 4×6, 6×6, 6×4, 8×6, 4×8 and so on. The largest return air grille is typically stops at 48 inches by 24 inches.

Face velocity is the amount of air volume passing through a grille. Typically, 500 fpm is an optimal balance between airflow and noise. Free area is the amount of space on a grille that is available for the air to pass through. It is about 70% on average. Find the product of multiplicand and 2nd least significant digit of 3-digit multiplier, and write down the product under the earlier product but the One’s place value of product should start from the Ten’s place value of multiplicand.With 80% free area, the resulted grille area is now 378 sq.in and a smaller grille size like 16×25 can be used. Find the product of multiplicand and most significant digit (MSD) of 3-digit multiplier, and write down the product under the earlier product but the One’s place value of product should start from the Hundred’s place value of multiplicand.