Siemens QAA22SS.EWSN Room Temperature Sensor – Selectable 0-10V / 0-5V / 4-20mA Output
Overview
The Siemens QAA22SS.EWSN is a wall-mounted room temperature sensor designed for HVAC/building automation systems. It supports selectable analog outputs (0-10V, 0-5V, or 4-20mA), powered by either 18-36 V DC or 24 VAC ±20%. With no local display or setpoint controls (“sensing only” type), it’s ideal for environments where stable, accurate temperature feedback is required without occupant adjustment. Its modern housing design, ventilation slots, and Siemens branding make it visually unobtrusive and functionally reliable.
Specifications
| Specification | Details |
|---|---|
| Brand / Model | Siemens QAA22SS.EWSN |
| Output Signal Options | Selectable: 0-10V, 0-5V, or 4-20mA |
| Power Supply | 18-36 V DC or 24 VAC ±20% |
| Measuring Temperature Range | 32°F to 122°F (0°C to 50°C) |
| Accuracy | ± 0.9°F (± 0.5°C) over measuring range |
| Element / Sensor Type | Sensing element (no display or HMI) |
| Enclosure Rating / Mounting | Wall-mount, white plastic housing, ventilation slots, no setpoint display |
| Enclosure Dimensions | ~ 4.5 in × 2.75 in × 1.18 in (≈ 115 mm × 70 mm × 30 mm) |
| Ambient / Operating Conditions | Standard indoor environments; mounts on wall; avoid direct sunlight, drafts, or heat sources |
| Certifications / Standards | UL 916, other Siemens / building control standards |
Features & Benefits
Flexible output signal options make it compatible with a wide variety of HVAC or building automation controllers.
Sensing-only type ensures no unauthorized changes in setpoints; good for locked or shared spaces.
Compact, sleek design with ventilation achieves faster response and blends into décor.
Reliable accuracy helps maintain comfort and energy efficiency.
Siemens brand ensures parts, quality, and compatibility in many control systems.
Applications
Room temperature monitoring in classrooms, offices, corridors, or conference rooms.
Building automation systems where temperature feedback is required for control loops.
Environments where setpoint control must be restricted and only centralized systems should adjust temperature.
Installation & Maintenance Notes
Mount sensor on an interior wall, about 4-5 ft. high, away from direct sunlight, air supply registers or heat sources.
Use proper wiring (per Siemens specifications) and avoid running sensor leads close to high-voltage or noisy electrical runs.
Seal any wall penetrations to prevent drafts from affecting readings.
Clean the ventilation openings occasionally to avoid dust buildup that could reduce response time.
Warranty & Quality Assurance
Made by Siemens to meet its internal quality control and design standards.
Meets applicable safety, indoor air quality, and building control certifications.
Related Products
Other QAA / Series 2200 sensors with display / setpoint adjustment (e.g. “FWSN” versions)
Sensors with resistive outputs (PT100, thermistor) rather than analog signal outputs
Accessories like sensor backplates, insulating gaskets, or matching trim plates








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