Airflow meter / Anemometer

These funnels fit perfectly on low-cost anemometers, allowing easy volume flow measurement to accurately regulate indoor ventilation systems.
I used a HoldPeak(R) HP-866B anemometer (approx. 20 Euro). This is inserted vertically into the adapter for mounting on the funnel and then carefully swivelled through 90° (see pictures).
The used funnel must cover the valve completely to get an accurate measurement. Part1 is the adapter for the anemometer with thread to screw on one of the two funnels (Part2 or Part3).
To determine the volume flow, the indicated wind speed in m/s has to be multiplied with the corresponding factors to get the volume flow in m³/h. In my case, for supply air it was x 9.7, for exhaust air x 10.5. (Yes, there is a difference in the factors to be applied for supply air and exhaust air. This is also the case with professional equipment).
I have taken the smaller funnel here for the STC and STH valves from Zehnder, the larger funnel fits and centres perfectly over