Siemens QFM2101 is a duct-mounted relative humidity sensor in the Q-Series that provides a 4–20 mA current loop output for HVAC control. It operates on DC power from 13.5 to 35 V and measures relative humidity from 0 to 100% RH with an accuracy of ±5% RH, using capacitive sensing in the air duct. As a 2-wire device, it outputs 4–20 mA proportional to humidity, enabling direct connection to HVAC controllers and building automation systems that monitor humidity levels for dehumidification and indoor air quality management.
