The 22UT-52 is a Belimo active 24V outdoor air temperature sensor with a compact 1" (25 mm) external probe extending from the housing. The unit measures outdoor air temperature for weather compensation, cold-storage monitoring, greenhouses, production plants, warehouses, and any application requiring an outdoor-rated air temperature reading. The sensing element is a Pt1000 1/3 DIN active resistance probe with eight jumper-selectable measuring ranges (from -50 to 130°C / -30 to 250°F envelopes), giving ±0.9°F accuracy at 70°F in the typical S2/S4 settings. Output is 0-5V / 0-10V active (jumper-selectable). The NEMA 4X / IP65 polycarbonate housing handles all outdoor weather conditions, and a 1/2" NPT conduit adapter ships in the box for direct connection to standard electrical conduit.
Outdoor air temperature monitoring for BAS weather compensation (boiler/chiller reset based on OAT), cold storage warehouse monitoring, greenhouse climate control, production plant outdoor air tracking, and any application where a NEMA 4X / IP65 outdoor-rated sensor with a compact form factor is required. For the same sensor with 4-20 mA output (useful for long cable runs or controllers preferring current loops), see 22UT-54. For deeper sensor insertion (longer immersion probe rather than the compact 1" external sensor), see the 22UT-52H / 52L family of extended-probe outdoor air sensors.
Key Features
The 1" (25 mm) probe extends from the housing exterior — simpler than longer extended-probe variants. Sufficient sensor exposure for ambient outdoor air while keeping the overall package small for tight mounting locations on exterior walls or under eaves.
On-board jumper selects the output range: 0-5V or 0-10V. Matches the sensor to whatever input range the BAS controller expects without specifying a different SKU. Both AC and DC supply supported (19-29 VAC, 15-35 VDC).
On-board jumper selects one of eight temperature measuring ranges from -30 to 250°F envelopes. Choose the narrowest range that covers your expected operating point — narrower ranges give higher analog resolution. Settings include wide-envelope outdoor air (-30 to 130°F), HVAC supply air (20-110°F), occupied comfort range (50-95°F), and several others.
Active Pt1000 platinum resistance with 1/3 DIN tolerance class — ±0.5°C at 21°C / ±0.9°F at 70°F at the S2/S4 settings. Long-term stability ±0.07°F per year — no field calibration required for the lifetime of the sensor.
Outdoor-rated polycarbonate housing for direct exposure to weather: rain, snow, UV, dust, and washdown. UL Enclosure Type 4X. The housing is designed to mount directly on an exterior wall or building under-eave location without requiring additional weather protection.
Conduit adapter ships in the box for direct connection to standard 1/2" NPT electrical conduit. Cable gland with strain relief supports ø6-8 mm cable diameter for installations without conduit. Pluggable spring-loaded terminal block (max 2.5 mm²).
Compatible with standard 24V control transformers shared with actuators and other sensors. Power consumption: 0.8 VA AC / 0.4 W DC (24 VAC/VDC supply).
Industry-leading factory warranty backed by Belimo's worldwide service network.
Selectable Measuring Ranges (Jumper S0–S7)
The active measuring range is set via on-board jumper. Choose the narrowest range that covers your expected operating point for highest analog resolution; choose a wider range for general-purpose monitoring with broader coverage.
| Setting | Range | Note |
|---|---|---|
| S0 | -30 to 130°F (-50 to 50°C) | |
| S1 | 0 to 250°F (-10 to 120°C) | |
| S2 | -40 to 130°F (-40 to 55°C) | ★ Factory setting (22UT) |
| S3 | -30 to 230°F (-35 to 110°C) | |
| S4 | 20 to 110°F (-5 to 45°C) | ★ Factory setting (22MT) |
| S5 | 50 to 95°F (10 to 35°C) | |
| S6 | 50 to 122°F (10 to 50°C) | |
| S7 | 32 to 122°F (0 to 50°C) |
Technical Specifications
| Specification | Detail |
|---|---|
| Sensor Style | Active temperature transducer for outdoor air |
| Measured Value | Air temperature (outdoor) |
| Measuring Fluid | Air |
| Sensing Element | Pt1000 1/3 DIN point sensor at probe tip |
| Output Signal | 1× active analog: 0-5V or 0-10V (jumper-selectable) |
| Output Load | min. 5 kΩ load resistance |
| Multirange | 8 jumper-selectable measuring ranges (S0 through S7) |
| Temperature Accuracy | ±0.5°C at 21°C (±0.9°F at 70°F) at S2 and S4 settings |
| Long-Term Stability | ±0.04°C per year at 21°C (±0.07°F per year at 70°F) |
| Probe Length | 1" (25 mm) |
| Probe Material | Stainless steel |
| Time Constant (typical, in room air) | 542 s (slow response by design for outdoor air averaging) |
| Application | Outdoor air temperature monitoring |
| Mounting | Exterior wall, under eave, or any outdoor-rated location |
| Power Supply | 24 VAC/VDC (AC 21.6-26.4V / DC 13.5-26.4V for 22UT; AC 19-29V / DC 15-35V for 22MT) |
| Power Consumption | 0.8 VA AC / 0.4 W DC |
| Electrical Connection | Pluggable spring-loaded terminal block, max 2.5 mm² |
| Cable Entry | Cable gland with strain relief, ø6-8 mm; 1/2" NPT conduit adapter included |
| Housing Material | Polycarbonate |
| Enclosure Rating | NEMA 4X / IP65, UL Enclosure Type 4X |
| Protection Class | IEC/EN III, PELV (Protective Extra-Low Voltage) |
| Ambient Humidity | Max. 95% RH, non-condensing |
| EU Conformity | CE Marking |
| Certification | IEC/EN 60730-1 |
| Quality Standard | ISO 9001 |
| Manufacturer | Belimo |
| Manufacturer Part Number | 22UT-52 |
| Warranty | 5-year factory warranty |
What's In the Box
- 22UT-52 outdoor temperature sensor with 1" (25 mm) external probe in polycarbonate housing
- 1/2" NPT conduit adapter
- Cable gland with strain relief
- Mounting screws and dowels
Documentation
Frequently Asked Questions
What does the 22UT-52 measure and output?
It measures outdoor air temperature via a 1" (25 mm) external Pt1000 probe extending from the housing. Output is 0-5V / 0-10V active (jumper-selectable). Eight jumper-selectable measuring ranges let you match the sensor to the application — from wide-envelope outdoor air (-30 to 130°F at S0) to narrow comfort-range settings.
How is this different from the 22UT-52H/L family?
The base 22UT-52 (this SKU) has a compact 1" (25 mm) external probe. The H/L variants have longer integrated probes for deeper sensor insertion or specific temperature range optimization (H = high-temperature variants, L = low-temperature variants). Choose the base 22UT-52 for standard outdoor air monitoring where the compact form factor is preferred and the 8 jumper-selectable ranges cover the application.
Why is the time constant so long (~542 seconds)?
The long time constant (~9 minutes for 63% of step change) is intentional. Outdoor air sensors are typically used for weather compensation — boiler supply temperature reset, chilled water supply reset, economizer changeover logic — where transient gusts of cold or warm air would otherwise cause controller hunting. The slow response damps short-term temperature swings (brief sun exposure, wind chill events) so the controller reacts to actual sustained outdoor conditions, not noise. If you need fast response for outdoor air, this isn't the right sensor.
Where can I install this sensor?
Outdoor — exterior wall, under-eave location, or any weather-exposed surface. NEMA 4X / IP65 rated for rain, snow, UV, and washdown. Best practice: mount on a north-facing exterior wall (avoids direct sun heating) at 5-10 ft above grade, away from heat sources like exhaust vents, chimneys, or refrigerant compressor discharge lines.
How do I configure the 8 measuring ranges?
The active measuring range is set via an on-board jumper (settings S0-S7). Open the housing, locate the range-select jumper, move it to the desired position, and close the housing. The factory default is S2 for outdoor air (22UT) or S4 for typical HVAC duct applications (22MT). Choose the narrowest range that covers your expected operating point — narrower ranges give higher analog resolution. For example, 0-10V mapped across 50-95°F gives ~0.2V per °F, vs ~0.05V per °F for the same output mapped across -30 to 250°F. The narrower range gives 4× the resolution at the BAS input.
Does it need 24V power?
Yes — 24 VAC or 24 VDC supported. Power consumption is 0.8 VA AC / 0.4 W DC — very low draw, compatible with standard 24V control transformers shared with actuators and other sensors.
- Sensor Type:
- Outdoor Air Temperature
- Sensing Element:
- Pt1000 1/3 DIN point sensor
- Output Signal:
- Temperature (single output)
- Output Style:
- Active Transmitter (V)
- Output Type:
- 0-5V / 0-10V (jumper)
- Power:
- 24 VAC/VDC
- Number of Outputs:
- 1 analog
- Multirange:
- 8 jumper-selectable measuring ranges
- Temperature Accuracy:
- ±0.9°F at 70°F (S2/S4 settings)
- Long-Term Stability:
- ±0.07°F per year at 70°F
- Probe Length:
- 1 (25 mm)"
- Probe Style:
- External point sensor
- Application:
- Outdoor air
- Mounting:
- Outdoor wall/eave
- Conduit:
- 1/2 NPT (included)"
- Enclosure:
- NEMA 4X / IP65
- Display:
- No Display
- Supported Protocols:
- Analog only (no bus)
