I used Alerton Dual Duct VAV controllers to control 12 operation rooms. I made a custom application to use the hot deck airflow sensors for the return air CFM. (return boxes located on another floor) All is well until the air balancer shows up. He says the calibration factor is too high on these return boxes and he reads a different pressure at the pickup tubes on the return VAV and the controller airflow sensor. Personally I don’t see a problem as long as I read proper CFM. Who cares what the calibration factor is? Pressure drop -- who cares as long as it is in proportion and doesn’t affect accuracy of the CFM reading. What I need is some documentation that I can use showing the affects of tube length etc. I would really appreciate any help.
Are all balancers pot heads?