Can somebody tell me the explanation for following; We have AHU unit specified as 9900m3/h which is working at the moment 9000m3/h (value shown on AHU controller). When we measure the air flow in the main duct (600x600mm) our results show that the flow is 12000m3/h (and we know that this is wrong). We conduct measurement with the hot wire anemometer, which is 1 month old (and calibrated). Probe is placed at the side of the duct, value recorded at 5 different points, from center to duct wall, and afterward we multiple average value with the duct cross-sectional area. Does somebody can conclude what we did wrong? Is there a different method of measuring and determining average velocity?
Thanks in advance,