The 01ST-5B3 is a Belimo passive surface contact temperature sensor with a Pt 1000 (1000Ω Platinum RTD) element on a brass surface probe, terminated directly into 6.5 ft of tinned copper shielded plenum cable, green jacket, 22AWG, 2-wire, 300 V. It strap-mounts to pipe and arched surfaces using the included A-22P-A47 fixing strap (fits pipes up to 110 mm / 4.3" OD) — no junction box on the pipe, no terminal block to land in the field. The cable runs back to the panel and lands directly on the controller's analog input. The signal returns as a passive resistance — no 24V supply or signal conditioning required.
Chilled-water and hot-water pipe temperature sensing where the controller panel is within cable reach and you want clean panel-side terminations — no junction box on the pipe. Ideal for retrofits, mechanical room consolidations, and any install where draining the loop or installing a thermowell isn't practical. Same brass-probe thermal performance as the 01HT, but with cable-out termination instead of a housed terminal block.
Key Features
Brass probe maintains thermal coupling to the pipe surface for fast, accurate reading. With thermal paste, the typical 63% time constant is just 17 seconds on a water pipe.
Terminated directly into 6.5 ft (2 m) of plenum-rated cable that lands at your controller panel. No junction housing on the pipe means cleaner installs in tight mechanical-room runs and faster terminations.
Mounts in minutes with the included A-22P-A47 fixing strap (fits pipes up to 4.3" OD). No pipe penetration, no shutdown, no draining the loop. For larger pipes up to 9.8" OD, use the A-22P-A49 strap (linked below).
Probe and cable jacket are both rated -40 to 300°F (-40...300°F [-40...150°C]). Suitable for hot-water loops, chilled water, and many process applications without an additional high-temp upgrade.
Factory-trimmed Pt 1000 element delivers stable long-term accuracy with no field calibration required.
Industry-leading factory warranty backed by Belimo's worldwide service network.
Technical Specifications
| Specification | Detail |
|---|---|
| Sensor Style | Pipe surface contact temperature sensor with brass probe and integral cable |
| Measured Value | Temperature (pipe surface) |
| Sensing Element | Pt 1000 (1000Ω Platinum RTD) |
| Measuring Range | -40...300°F [-40...150°C] |
| Application | Water — pipe surface contact |
| Pipe Compatibility | Up to 4.3" [110 mm] OD with included A-22P-A47 strap; up to 9.8" [250 mm] OD with A-22P-A49 accessory strap |
| Mounting | Strap-on (no penetration, no thermowell required) |
| Probe Material | Brass |
| Cable | 6.5 ft [2 m] tinned copper shielded plenum cable, green jacket, 22AWG, 2-wire, 300 V, rated -40 to 300°F |
| Electrical Connection | 2-wire, terminate directly at controller analog input |
| Enclosure Rating | IP65, UL 2043 plenum compliant |
| Protection Class | IEC/EN III, Protective Extra-Low Voltage (PELV) |
| UL Approval | cULus per UL60730-1A/-2-9, CAN/CSA E60730-1/-2-9 |
| UL 2043 Compliance | Suitable for use in air plenums per NEC 300.22(C) and IMC Section 602 |
| Time Constant τ (63%) | 17 s on water pipe with thermal paste |
| Power Required | None — passive resistance element |
| Weight | 0.13 lb [0.06 kg] |
| Manufacturer | Belimo |
| Manufacturer Part Number | 01ST-5B3 |
| Warranty | 5-year factory warranty |
What's In the Box
- 01ST-5..3 surface contact sensor with brass probe and 6.5 ft plenum-rated cable
- A-22P-A47 fixing strap — fits pipes up to 110 mm (4.3") outside diameter
For optimal accuracy, Belimo recommends thermal paste between the brass probe and the pipe surface. The included A-22P-A47 strap does not ship with paste — see the A-22P-A40 / A-22P-A42 (paste pre-applied straps) or A-22P-A44 (paste-only syringe) in Compatible Accessories below.
Compatible Accessories
Documentation
Frequently Asked Questions
Does this need 24V power?
No. The 01ST-5B3 is a passive resistance temperature sensor — the controller reads its element directly through the analog input. No 24V supply or signal conditioner needed.
What sensing element is in the 01ST-5B3?
The 01ST-5B3 uses a Pt 1000 (1000Ω Platinum RTD). The letter between '01ST-5' and the trailing '3' identifies the element: A=Pt 100, B=Pt 1000, E=Ni 1000 (JCI), L=NTC 10K Type II, M=NTC 10K Type III (Precon), Q=NTC 20K. Match this to your controller's input curve.
Why does the SKU end in '3'?
The trailing '3' in the SKU denotes the 6.5 ft cable variant. All 01ST-5..3 products ship with this same plenum-rated cable; there is currently no longer-cable variant in the 01ST family. For longer cable runs, splice in an extension at the panel side or use a wall-mounted junction box.
What pipe size does the included strap fit?
The included A-22P-A47 strap fits pipes up to 4.3" (110 mm) outside diameter — covers most copper and steel pipe through 4" nominal. For larger pipes up to 9.8" OD, use the A-22P-A49 accessory strap (linked above).
Do I need thermal paste for accurate readings?
Belimo specifies thermal paste between the brass probe and the pipe for the rated 17-second time constant. Without paste, response slows and absolute accuracy drops by a few tenths of a degree. The included A-22P-A47 strap does not include paste — use A-22P-A44 (syringe) to add paste, or upgrade to A-22P-A40 / A-22P-A42 (straps with paste pre-applied).
What temperature range does it handle?
-40...300°F [-40...150°C]. Both the brass probe and the cable jacket are rated to the same temperature, which is wider than the 01HT's range — useful for higher-temperature hot-water and process loops.
Does it work with my BAS?
Any BAS controller with a temperature input configured for the Pt 1000 curve will read this sensor directly. See the linked Resistance Characteristics PDF for the full curve table at standard temperature points.
How is this different from the 01HT pipe sensor?
Both are strap-on pipe surface contact sensors with the same 6 element options. The difference is termination: the 01HT has a NEMA 1 housing on the pipe with a pluggable terminal block (good for accessible mechanical rooms or where local termination is preferred). The 01ST is cable-out — no housing on the pipe, the cable runs directly to your panel (cleaner installs in tight runs, no field-side junction work). Choose 01ST when the panel is within 6.5 ft and you want the cleanest install.
- Sensor Type:
- Pipe Mount
- Output Signal:
- Temperature Only
- Temperature Element:
- 1K Platinum RTD
- Humidity Element:
- None
- CO2 Element:
- None
- VOC Element:
- None
- Display:
- No Display
- Setpoint:
- No Setpoint
- Override:
- No Override
- Lead Length:
- 6 ft Plenum Rated Cable
- Supported Protocols:
- None
- Enclosure:
- No Box
