Return Grille Size For 4 Ton

Air return intakes sizes and capacities.

Return grille size for 4 ton. Engineering toolbox resources tools and basic information for engineering and design of technical applications. Measure and verify the grille is pulling the required airflow from the conditioned space after the job is completed and the system has started. The square root of 576 is 24. Note also the return air grille sizing formula at the top of the chart.

Since from this example the furnace requires 400 square inches for your filter grille you may use either the 25 by 16 filter grille or the 20 by 20 filter grille. In order to determine the size of the tonnage you have simply divide 980 by 400 cfm per ton. Using those examples you would see their square inches are 280 400 and 400 respectively. Search is the most efficient way to navigate the engineering toolbox.

4 ton unit x 144 square inches 576 squared. Always round up and we have a tonnage value of 2 5. A return air grill should be sized for an air speed of 300 500 fpm feet per minute. Therefore your return air duct and grill size will be 24 by 24 inches.

You can never have to much return air as a hvac contractor you want no less than 144 square inches per ton. Size and capacity of air return intake. Size the return grille and duct to remove 340 cfm from the pressure zone according to your favorite duct sizing method. One additional diagnostic step to assure duct leakage and thermal duct loss is low.

Doing this for this space will yield a tonnage of 2 45. 400 fpm is the median air speed for this calculation. Calculate the square root of the total. Some of the common sizes include 20 by 14 25 by 16 and 20 by 20.