The 01RT-5B-0 is a Belimo passive wall-mount room temperature sensor with a Pt 1000 (1000Ω Platinum RTD) element and an integrated manual override button. The override button momentarily shorts the sensor element on the same two wires used for temperature sensing — no separate discrete input is required at the controller. The DDC detects the resulting 0-ohm reading as an override request and runs whichever HVAC sequence the programmer has configured (extended occupancy, night-setback override, after-hours run, etc.). The sleek white housing supports both in-wall (back wire entry) and on-wall (top/bottom wire entry) mounting on standard junction boxes.
Conference rooms, classrooms, training rooms, and any commercial space where occupants need an after-hours override without giving them a setpoint adjustment. Ideal for retrofits where the existing control wiring is two-conductor only and running an additional discrete input back to the panel isn't practical. Also a clean fit for light-commercial and high-end residential applications wanting a minimalist room device.
Key Features
The override button shorts the thermistor on the same two wires used for temperature sensing. The DDC detects the 0-ohm signal as an override request — no dedicated discrete input, no extra cable pair, no relay needed at the panel.
Factory-trimmed Pt 1000 element delivers stable long-term accuracy with no field calibration required.
Wire entries at the back (in-wall, standard junction box) or top/bottom (on-wall, surface-mount conduit). Adapts to existing wiring without extra hardware.
Passive resistance returns directly to the controller — no 24V supply, no signal conditioning, no scaling required.
Low-profile white polycarbonate (RAL 9003) blends with most commercial wall finishes. Spring-loaded terminal accepts 0.5–1.5 mm² conductors.
Industry-leading factory warranty backed by Belimo's worldwide service network.
Technical Specifications
| Specification | Detail |
|---|---|
| Sensor Style | Wall-mount room temperature sensor with manual override button |
| Measured Value | Temperature (room air) |
| Sensing Element | Pt 1000 (1000Ω Platinum RTD) |
| Measuring Range | 32...122°F [0...50°C] |
| Application | Indoor air — room temperature |
| Override Function | Momentary push-button shorts the sensor element to 0 Ω; DDC interprets the signal as an override event |
| Mounting | In-wall (rear wire entry, standard junction box) or on-wall (top/bottom wire entry, surface conduit) |
| Wiring | 2-wire — temperature signal and override share the same conductor pair |
| Electrical Connection | Spring-loaded terminal, 0.5–1.5 mm² |
| Housing | Polycarbonate, white (RAL 9003) |
| Enclosure Rating | NEMA 1 / IP30 (UL Enclosure Type 1) — indoor wall mount only |
| Protection Class | IEC/EN III, Protective Extra-Low Voltage (PELV) |
| Certification | IEC/EN 60730-1 and IEC/EN 60730-2-9 |
| Time Constant τ (63%) | 360 s in still room air |
| Wall Coupling Factor | 35% — installation note in datasheet |
| Power Required | None — passive resistance element |
| Weight | 0.19 lb [0.09 kg] |
| Manufacturer | Belimo |
| Manufacturer Part Number | 01RT-5B-0 |
| Warranty | 5-year factory warranty |
What's In the Box
- 01RT-5..-0 room temperature sensor in white wall-mount housing
- Mounting screws
The 01RT mounts directly to a standard junction box (in-wall) or to the wall surface (on-wall) using the included screws. No backplate, junction box, or cover plate is required.
Documentation
Frequently Asked Questions
Does this need 24V power?
No. The 01RT-5B-0 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 01RT-5B-0?
The 01RT-5B-0 uses a Pt 1000 (1000Ω Platinum RTD). The letter between '01RT-5' and '-0' identifies the element: B=Pt 1000, L=NTC 10K Type II, M=NTC 10K Type III (Precon), Q=NTC 20K. Note that the 01RT family does not offer Pt 100 or Ni 1000 variants — only the four elements above. Match this to your controller's input curve.
How does the manual override button work?
Pressing the button momentarily shorts the thermistor element to 0 Ω. The DDC sees a sudden drop to 0-ohm resistance (which corresponds to a temperature reading well below the sensor's range) and recognizes this as an override request. The DDC programmer writes logic to detect this condition and trigger whatever HVAC sequence is desired — extending occupied hours, overriding a night setback, starting an after-hours timer, etc.
Do I need a separate discrete input for the override?
No — that's the elegance of this design. The override signal travels on the same two wires as the temperature signal. Most legacy and modern DDCs can be programmed to interpret the 0-ohm reading as an override event without adding any hardware.
How do I detect the override on my BAS controller?
In your DDC programming, monitor the analog input for a value at or below the 0-ohm boundary. For example, on an NTC 10K Type III input, room temp at 32°F reads around 33,000 ohms; an override-pressed reading is 0 ohms — easily distinguished. Most BAS tools include a comparison block; trigger your override sequence when the reading falls below the lowest expected room value (e.g., 100 ohms).
What temperature range does it handle?
32...122°F [0...50°C] — the typical occupied-room range. The 01RT is purpose-built for indoor room temperature sensing; it is not rated for ducts, outdoor air, or process applications.
Can this be installed outdoors or in a wet area?
No. The 01RT is rated NEMA 1 / IP30 — indoor wall mount only. For outdoor air temperature, use the 01UT family. For wet locations, use the 01DT (NEMA 4X) duct sensor.
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.
- Sensor Type:
- Wall 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:
- Override
- Supported Protocols:
- None
- Material:
- Polycarbonate, White
- Enclosure:
- NEMA 1 Enclosure
