The 22PF-5UH is a Belimo ultrasonic flow sensor for water and water-glycol systems in heating and cooling applications. The flow body uses ultrasonic time-of-flight measurement (no moving parts, no wear, maintenance-free) with automatic temperature and glycol compensation up to 60% glycol by volume. The 5U base variant fits a DN50 (2") pipe with internal NPT (female) thread connection and reports flow rates from 0.2% of full scale up to a full scale of 79.2 GPM. Integration via BACnet MS/TP, Modbus RTU, MP-Bus, and a configurable 0-10V analog output. Configuration is via NFC using the free Belimo Assistant 2 mobile app — no commissioning laptop required. NIST, SI, and BIPM-traceable calibration provides defensible measurement accuracy for plant submetering, balancing, and trending applications that don't require full BTU/energy calculation.
Flow rate measurement and monitoring on chilled water, hot water, and water-glycol heating/cooling loops where the BMS needs accurate volumetric flow data but does NOT need on-board BTU/energy calculation. Typical applications: balancing valve verification, flow trending for diagnostics, terminal unit flow monitoring (VAV reheat, chilled beams, fan coils), pump-station flow visibility, and primary/secondary loop balancing in central plants. The 22PF gives you the same ultrasonic flow sensing platform as the 22PE thermal energy meter but at a significantly lower price point by leaving out the dual-Pt1000 temperature pair and the energy calculation engine. For installs that need condensation prevention (humid mech rooms, unconditioned plant rooms), see the 22PF-5XU family with optional 21W heaters.
The 22PF measures volumetric flow only (plus a single internal temperature reading used for glycol/temp compensation). It does NOT calculate BTU or thermal energy. If you need actual energy submetering for tenant billing, central plant efficiency tracking, or ASHRAE 90.1 mandatory energy submetering compliance, choose the 22PE Thermal Energy Meter instead — it adds a second Pt1000 temperature sensor (external T1 with 3m cable for the return-side measurement) and the BTU calculation engine, plus Ethernet/PoE/Belimo Cloud connectivity. The 22PF is the right choice when the BMS just needs to know how much fluid is flowing through the pipe.
Calibration chain documented back to NIST, SI, and BIPM — defensible flow measurement accuracy. Carries IEC/EN 60730-1:11 and IEC/EN 60730-2-15:10 certification; ISO 9001 quality standard; cULus-listed per UL94.
Key Features
Ultrasonic transit-time measurement across a 2" flow section — no impeller, no turbine, no obstruction in the flow path. Maintenance-free for the lifetime of the sensor; no bearing wear, no calibration drift from mechanical components. Velocity range 0.08-7.73 FPS.
An internal temperature sensor measures the fluid temperature and the meter applies automatic density and viscosity corrections to the flow calculation. Configure the glycol mix percentage (0-60% by volume) during commissioning via NFC and the sensor handles the corrections internally — accurate flow readings across the full operating temperature range and any standard glycol concentration.
Three serial integration paths over RS-485 from a single device. Belimo MP-Bus for daisy-chain integration with Belimo actuators (up to 8/16 devices per bus). Full BACnet object list and Modbus register map available in the included interface description PDFs. For installations requiring BACnet/IP or Modbus TCP, see the 22PE Thermal Energy Meter.
User-defined voltage output: 0-10V, 0.5-10V, 2-10V — or define custom upper/lower limits via NFC. Max load 1 mA. Useful as a backup signal path or for direct integration with controllers that don't speak BACnet/Modbus.
NEMA 2 rating for indoor mechanical room installs. UL Enclosure Type 2 listed; cULus to UL94. For NEMA 4 outdoor or washdown applications, see the 22PF-5XU family.
Tap any NFC-capable iOS or Android phone to the sensor to read live flow data, configure scaling/output type, set BACnet device instance and MAC, or update configuration — no commissioning laptop, no vendor-specific dongles, no driver installs. The Belimo Assistant 2 app is a free download. NFC works without external power, useful for pre-commissioning before the sensor is wired up.
Internal NPT (female) thread process connection — installers thread the flow body directly onto an existing male-NPT pipe nipple or threaded coupling. No special transition fittings required for standard US HVAC piping. Body pressure rating 360 psi.
Per EN 1434-4:2022, the 22PF requires no upstream straight-pipe run to meet the specified flow accuracy. Install directly after an elbow, tee, or valve without degradation — significant advantage in tight mechanical rooms where straight runs aren't available.
Technical Specifications
| Specification | Detail |
|---|---|
| Type | Ultrasonic Flow Sensor (flow measurement only — no BTU/energy calculation) |
| Pipe Size | DN50 (2") |
| Pipe Connection | Internal thread NPT (female) |
| Pressure Rating | 360 psi (body pressure rating) |
| Full Scale Flow (FS) | 79.2 GPM (maximum flow) |
| Minimum Measurement | 0.158 GPM (0.2% of FS) |
| Velocity Range | 0.08-7.73 FPS |
| Measurement Principle | Ultrasonic time-of-flight, with temperature + glycol compensation |
| Flow Accuracy (20-100% FS) | ±2% of measured value at 68°F / 0% glycol |
| Flow Accuracy (0-20% FS) | ±0.4% of FS at 68°F / 0% glycol |
| Measurement Repeatability | ±0.5% of flow |
| Calibration Traceability | NIST, SI, and BIPM-traceable |
| Compatible Fluid | Chilled or hot water, water-glycol mixture up to 60% by volume (closed-loop only; open loop and steam not permitted) |
| Voltage Output | 1x 0-10V / 0.5-10V / 2-10V / user-defined (DC, max 1 mA load) |
| Communication | BACnet MS/TP, Modbus RTU, MP-Bus |
| MP-Bus Capacity | Up to 8 (16) devices per bus |
| Configuration | NFC via Belimo Assistant 2 mobile app |
| Nominal Voltage | AC/DC 24 V |
| Voltage Frequency | 50/60 Hz |
| Voltage Range | AC 19.2-28.8 V; DC 21.6-28.8 V |
| Power Consumption | 2.2 VA AC / 1.1 W DC |
| Supply Cable | 6x 0.75 mm² (multi-conductor) |
| Servicing | Maintenance-free |
| Inlet Length Required | ≥0 × DN per EN 1434-4:2022 (no straight-pipe requirement) |
| Protection Class | IEC/EN III, PELV (Protective Extra-Low Voltage) |
| NEMA Rating | NEMA 2 |
| UL Enclosure | Type 2 |
| Certification | IEC/EN 60730-1:11, IEC/EN 60730-2-15:10, cULus per UL94, NIST/SI/BIPM-traceable, ISO 9001 |
| Ambient Temperature | -22 to 131°F (-30 to 55°C); UL: -22 to 122°F (-30 to 50°C) |
| Fluid Temperature | -4 to 250°F (-20 to 120°C); frost protection required below 36°F (2°C) |
| Storage Temperature | -40 to 176°F (-40 to 80°C) |
| Ambient Humidity | Max. 95% RH, non-condensing |
| Pollution Degree | 3 |
| Cable Material | PVC |
| Flow Body Material | Brass nickel-plated |
| Fluid-Wetted Parts | Brass nickel-plated, brass, stainless steel, PEEK, EPDM |
| Manufacturer | Belimo |
| Manufacturer Part Number | 22PF-5UH |
| Warranty | 5-year factory warranty |
What's In the Box
- 22PF-5UH ultrasonic flow sensor: nickel-plated brass flow body (2" DN50) with integrated electronics housing
- Multi-conductor supply cable (6x 0.75 mm², factory-terminated on logic module)
- Integrated temperature sensor (factory-installed inside flow body for compensation)
- Threaded process connections sized for the flow body
Sold separately: NPT pipe nipples or threaded couplings sized to your piping. Companion ultrasonic energy meter (with BTU calculation): see 22PE family.
Documentation
Frequently Asked Questions
What does the 22PF-5UH measure?
Volumetric flow through a DN50 (2") pipe using ultrasonic time-of-flight measurement (no moving parts). Full scale 79.2 GPM; minimum measurable flow 0.158 GPM (0.2% of FS); velocity range 0.08-7.73 FPS. An internal temperature sensor measures fluid temperature and the meter applies automatic glycol + temperature compensation to the flow calculation. Flow is reported via BACnet MS/TP, Modbus RTU, MP-Bus, or the configurable 0-10V analog output.
Does the 22PF calculate BTU or thermal energy?
No — the 22PF measures flow only. It has a single internal temperature sensor used for compensating the flow calculation, but it does not have a second external temperature sensor (no return-side measurement) and does not calculate thermal energy. For BTU/energy submetering, choose the 22PE Thermal Energy Meter instead — same ultrasonic flow body but with the dual Pt1000 sensors and BTU calculation engine included.
What's the difference between the 5U and 5XU variants?
Both families use the same ultrasonic flow body and electronics. The 5XU adds optional condensation-prevention heaters (humidistat-controlled or thermostat-controlled, 21W) and is rated NEMA 4 (the heater housing raises the enclosure rating from NEMA 2 to NEMA 4 — useful for outdoor, washdown, or humid mechanical room installations). Choose the 5U for standard indoor mechanical rooms where condensation isn't a concern; choose the 5XU for chilled-water installs in humid or unconditioned spaces.
How does the BACnet/Modbus integration work?
Connect to the RS-485 terminals on the sensor and address it as a BACnet MS/TP or Modbus RTU device. Set the device instance / Modbus address and baud rate via NFC during commissioning (use the free Belimo Assistant 2 app). The BACnet object list includes flow rate, fluid temperature, totalizer, alarm states, and configuration objects. Modbus register map is documented in the included Modbus-Register PDF. MP-Bus is available as a third protocol on the same RS-485 pair for daisy-chain integration with Belimo actuators.
Does it need straight pipe in front of it?
No. Per EN 1434-4:2022, the 22PF requires ≥0 × DN inlet length — no upstream straight-pipe run required to meet rated flow accuracy. Install directly after an elbow, tee, or valve. Significant install advantage in tight mechanical rooms where straight runs aren't available — unusual for ultrasonic flow meters and especially valuable on retrofits.
How accurate is it?
From 20-100% of full scale, accuracy is ±2% of the measured value. From 0-20% of FS, accuracy is ±0.4% of FS (constant absolute, relative to full scale). Measurement repeatability is ±0.5% of flow. Calibration is NIST/SI/BIPM-traceable with documented traceability chain. Suitable for diagnostic trending, balancing verification, and submetering applications that don't require billing-grade BTU/energy accuracy.
Can I configure it without proprietary software?
Yes. Configuration is via NFC tap with the free Belimo Assistant 2 app on any NFC-capable iOS or Android phone. No commissioning laptop, no vendor dongles, no driver installs. The app reads live values, lets you change BACnet device instance, Modbus address, baud rate, output scaling, glycol percentage, and unit selection. Configuration changes can be pushed without the sensor being powered — useful for pre-commissioning.
- Sensor Type:
- Ultrasonic Flow Sensor (flow-only, no BTU calculation)
- Measurement Principle:
- Ultrasonic time-of-flight
- Pipe Size:
- DN50 (2)"
- Pipe Connection:
- Internal NPT (female)
- Full Scale (FS):
- 79.2 GPM
- Min Measurable Flow:
- 0.158 GPM (0.2% of FS)
- Velocity Range:
- 0.08-7.73 FPS
- Pressure Rating:
- 360 psi (body)
- Flow Accuracy 20-100% FS:
- ±2% of measured value
- Flow Accuracy 0-20% FS:
- ±0.4% of FS
- Repeatability:
- ±0.5% of flow
- Glycol Compensation:
- Automatic, 0-60% by volume
- Calibration Traceability:
- NIST / SI / BIPM-Traceable
- Communication:
- BACnet MS/TP + Modbus RTU + MP-Bus
- Analog Output:
- 1x 0-10V / 0.5-10V / 2-10V / user-defined
- Configuration:
- NFC via Belimo Assistant 2
- Power:
- 24 VAC/VDC (no PoE)
- Sub-Family:
- 5U Base
- Flow Variant:
- Standard
- Condensation Prevention:
- None
- NEMA Rating:
- NEMA 2
- UL Enclosure:
- Type 2
- Fluid Temperature Range:
- -4 to 250 F (-20 to 120 C)
- Ambient Temperature Range:
- -22 to 131 F (-30 to 55 C), UL -22 to 122 F
- Compatible Fluid:
- Water / Water-Glycol (closed loop only)
- Maintenance:
- Maintenance-free (no moving parts)
- Inlet Length Required:
- 0 x DN (no straight pipe required)
- Flow Body Material:
- Brass nickel-plated
