Siemens QAC22 outside air temperature sensor, LG-Ni1000, -50…+70 °C, IP54
- Type: LG-Ni1000 (Landis & Gyr Ni1000, 1000 Ω at 0 °C)
- Measuring range: -50…+70 °C
- Accuracy: ±0.4 K at 0 °C
- Mounting: outdoor, wall-mounted; IP54
Where QAC22 is used
QAC22 supplies the outdoor air temperature signal to Siemens heating and ventilation controllers — the weather-compensated heating curve adjusts supply water temperature based on outdoor conditions. Typical applications: district heating substations, boiler rooms, and air handling units with Siemens Synco, RVD, RVA, RVL, Climatix, or Desigo controllers.
The light-grey polycarbonate housing minimises the effect of solar radiation on the measurement. A removable cover gives easy access to the terminal block; the cable enters via a PG11 gland from the bottom or the rear.
Technical specifications
| Parameter | Value |
|---|---|
| Model | Siemens QAC22 |
| Sensing element | LG-Ni1000 (1000 Ω at 0 °C) |
| Measuring range | -50…+70 °C |
| Accuracy | ±0.4 K at 0 °C |
| Time constant | ~840 s (massive housing — immune to transient spikes) |
| Connection | 2-wire, non-polarised |
| Cable entry | PG11 cable gland (bottom or rear) |
| IP class | IP54 |
| Ambient temperature | -50…+70 °C |
| Housing material | Polycarbonate, light grey |
| Dimensions (W × H × D) | 80 × 92 × 50 mm |
| Mounting | Wall-mounted, outdoor conditions |
When to choose QAC22
- Substations and boiler rooms with Siemens controllers (Synco / RVD / RVA / RVL / Climatix / Desigo)
- Air handling units with Siemens automation — outdoor air signal
- When a reliable, long-life outdoor sensor with IP54 protection is required
- Compatibility: Siemens controllers with LG-Ni1000 input — Synco 100/200/700, RVD1xx/2xx, RVA/RVL, Climatix POL6xx/8xx, Desigo. Not compatible directly with Pt1000 controllers (Danfoss ECL) or NTC10 controllers (Ouman) — the whole loop must use the same sensor characteristic.
B2B delivery and logistics via Amegata.lt
- 24-hour delivery across Lithuania (from our warehouse in Vilnius)
- Competitive B2B pricing — often below market average
- 30-day payment terms for companies (per contract)
- Free technical consultation on sensor-controller compatibility
Official Siemens catalogue: hit.sbt.siemens.com/QAC22
Frequently asked questions
How does LG-Ni1000 differ from Pt1000 and NTC10?
LG-Ni1000 (Siemens standard) — nickel element, 1000 Ω at 0 °C, temperature coefficient ~5000 ppm/K. Pt1000 (Danfoss standard) — platinum element, 1000 Ω at 0 °C, ~3850 ppm/K. Although resistance is equal at 0 °C, the curves diverge at other temperatures — they cannot be mixed. NTC10 (Ouman standard) — thermistor, 10 kΩ at 25 °C, β=3435, negative-coefficient curve of a completely different shape.
Can I use QAC22 in place of a Danfoss ESMT outdoor sensor?
Not directly. Danfoss ESMT is Pt1000, QAC22 is LG-Ni1000 — the signals are not interchangeable at the controller. If the system already has a Siemens controller with LG-Ni1000 input, QAC22 fits; if the system uses Danfoss ECL, use ESMT (or an equivalent Pt1000).
Where should the outdoor sensor be mounted?
On the north (or north-east) side of the building, at least 2.5 m above ground, not under a rain gutter, not above hot flue outlets, not in direct sun. Avoid windows and ventilation openings — leaking indoor air distorts the reading.
How to extend the sensor cable?
Use 2-wire shielded cable (e.g. 2 × 0.75 mm² LiYCY). Practical limit is about 100 m without signal distortion. Ground the shield only at the controller end (avoid a ground loop).
Does the sensor need calibration?
No. LG-Ni1000 characteristic is standardised — the sensor is not calibrated, it is replaced. If readings deviate significantly from a reference thermometer (>2 °C), check cable contacts and controller input configuration.
