Return Grille Size Calculator

Size and capacity of air return intake.

Return grille size calculator. Air flow calculator linear bar grilles. Return a return draws air into a return duct system with negative pressure compared to the space usually via a fixed grille but. 4 ton unit x 144 square inches 576 squared. S1200 max cfm for nc.

B air moving too fast will be noisy. The size of a grill the mechanical movement of air and the mathematics that govern the establishment of correct return air vents are determined by these organizations. The square root of 576 is 24. Search is the most efficient way to navigate the engineering toolbox.

Size the return grille and duct to remove 340 cfm from the pressure zone according to your favorite duct sizing method. A the slower the air is moving the better the filter can grab crap out of the air. Calculating return grill size is really a velocity issue because. Measure and verify the grille is pulling the required airflow from the conditioned space after the job is completed and the system has started.

Engineering toolbox resources tools and basic information for engineering and design of technical applications. Max cfm for nc 25 150 250 350 500 700 900 1200 1500 1800 2100 2400 2800 3500 4300 5900 7700. Cre500 max cfm for nc 25 150 300 450 600 850 1100 1400 1700 2000 2300 2800 3300 4100 5000 6000 9200. Double defl supply eggcrate return.

Scientific online calculator. A filter grill should be sized for a maximum face velocity of 300 fpm. Use the calculator below to quickly and easily determine the grille airflow. Installation standards and demands are adhered to in order to produce a standard of performance across the career field and ensure the professional installation of hvac systems.

Calculate the square root of the total. A non filtered grill should be sized for a maximum face velocity of 500 fpm. One additional diagnostic step to assure duct leakage and thermal duct loss is low. Therefore your return air duct and grill size will be 24 by 24 inches.

Multiply the lengths and widths of common filter grille sizes to calculate the square inches of each. Once you find one that meets or exceeds the above calculated needed number you can use it as your filter grille size. Return grille size times 2 gives u the amount of cfms u are getting out of the return air grille i e. Proper sizing and orientation of grilles registers and diffusers may seem like such a simple thing but it s an area where confusion and mistakes are commonly made.

Quick reference cfm chart for standard grilles. Some of the common sizes include 20 by 14 25 by 16 and 20 by 20.