What is meant by "Average Differential Pressure"? In my case, i have 4 janitor's closets and a recycling room on the same fan. There is no supply air served to these spaces, all make-up air is brought in from the undercut of the door. The fan will operate continuously so using the ASHRAE equation for Differential Pressure (∆P) in PA (Q=165.5*A*√∆P) for both the minimum and average differential pressures will yield the same result which is under 5 PA but more than 1 PA. is there a different equation to use or different parameters?
Thank you for your time in advance.