The QFA20... indoor temperature and humidity sensor from Siemens Building Technologies HVAC Products can measure relative humidity and temperature. It is suitable for use in ventilation and air conditioning systems, and features high accuracy and a wide operating voltage range.
This manual describes the Siemens QFA20 series indoor temperature and humidity sensors used in HVAC and building automation systems. It covers the sensor’s operating principle, measurement ranges, output signals, and the various model options (QFA2000, QFA2020, QFA2040, QFA2060).\n\nInstallation guidance includes wall‑mounting instructions, wiring recommendations, cable routing, and safety considerations. Technical data such as supply voltage, power consumption, protection rating, and environmental limits are listed, along with detailed wiring diagrams for each model.
| Working voltage | AC 24 V ±20 % or DC 13.5‑35 V |
|---|---|
| Humidity output signal | DC 0‑10 V (0‑100 % RH) |
| Temperature output signal | DC 0‑10 V (0‑50 °C or –35…+35 °C) |
| Humidity accuracy | ±3 % RH |
| Time constant (humidity) | 2 min |
| Protection rating | IP32 |
The sensor can be powered from AC 24 V ±20 % or DC 13.5 V to 35 V.
Mount the sensor on an interior wall, avoid direct sunlight or heat sources, and connect wiring from the rear or front as shown in the wiring diagram.
The sensor provides humidity accuracy of ±3 % RH within the comfort range.