The Belimo EV125+ARX-E N4HT is a 2-way 1-1/4" pressure independent characterized control valve (PI-CCV) with integrated thermal energy metering, rated 28.5 GPM nominal flow, driven by a non fail-safe ARX-E actuator in a NEMA 4 enclosure with a thermostat-controlled internal heater. It combines a characterized control valve, an ultrasonic flow sensor, supply and return temperature sensors and a communicating actuator in one assembly, so a single device controls flow, measures delivered energy and reports coil performance over BACnet, Modbus or MP-Bus.
Specifications sourced from belimo_EV125_ARX-E_N4HT_datasheet_en-us.pdf (Belimo exact assembly datasheet, rev 2026-08-19). Verified 2026-08-21.
Common Applications
- Air handling unit coils
- Computer room air conditioning units, where power control holds output as supply water temperature rises
- Plate heat exchangers separating primary and secondary circuits
- Branch and riser flow and delta T control on distribution to a floor or zone
- Applications requiring measured delivered energy, not just valve position
- Low Delta T remediation, where coil performance must be proven rather than assumed
- Wet, washdown or high-humidity mechanical rooms requiring a NEMA 4 rated enclosure
- Cold locations where an enclosure heater must engage on temperature
These are documented Belimo Energy Valve application families, not a manufacturer recommendation for this specific model. This valve is an EV4-generation product, on which design flow (V'max) is adjustable across 25-100% of its 28.5 GPM nominal flow, giving a selectable range of 7.12 to 28.5 GPM. Any application below is suitable only where the required design flow falls inside that range. Source: belimo_ev-4.0-operations_manual_en-us.pdf, Vmax setting, p.37; nominal flow from the exact-model datasheet.
Warranty
Belimo 5-Year Limited Warranty. Coverage is subject to Belimo's applicable Terms and Conditions of Sale and to any product-specific warranty requirements. See Section IX of the Belimo Energy Valve technical documentation for the full terms.
Key Features
Measures delivered energy
An ultrasonic flow sensor plus supply and return temperature sensors compute actual thermal energy through the coil, so the valve reports BTU delivered rather than inferred position.
Pressure independent control
The characterized control valve holds the commanded flow across the stated differential pressure range, so balancing valves and repeat commissioning are not required.
Manages Delta T
Belimo Delta T Manager logic limits flow when the coil is not producing useful temperature difference, addressing Low Delta T Syndrome and reducing pumping energy.
Native BACnet, Modbus and MP-Bus
Communication is integral to the actuator: BACnet/IP, BACnet MS/TP, Modbus TCP, Modbus RTU and MP-Bus are supported directly, with no separate protocol gateway.
NEMA 4 with thermostat-controlled internal heater
The enclosure carries a NEMA 4 rating and an internal heater, cycled on measured temperature to keep the housing above the condensation point.
Technical Specifications
| Valve Pattern | 2-way |
| Valve Size | 1.25" [32] |
| Nominal Flow (V′nom) | 28.5 GPM |
| Body Pressure Rating | 360 psi |
| Differential Pressure Range | 5...50 psi / 1...50 psi, see "Flow Reduction Chart" |
| Flow Characteristic | equal percentage or linear |
| Fluid | chilled or hot water, up to 60% glycol max (open loop/steam not allowed) |
| Fluid Temperature | 14...250°F [-10...120°C] |
| Pipe Connection | Internal thread / NPT (female) |
| Flow Measurement Accuracy | ±2% @ 20°C [68°F] |
| Flow Repeatability | ±0.5% (Flow) |
| Flow Sensor Technology | Ultrasonic with glycol and temperature |
| Nominal Voltage | AC/DC 24 V |
| Voltage Range | AC 19.2...28.8 V / DC 21.6...28.8 V |
| Power Consumption (Running) | 26W |
| Transformer Sizing | 30 VA |
| Ethernet Connection | RJ45 socket |
| Power over Ethernet | DC 37...57 V |
| Communicative Control | BACnet/IP, BACnet MS/TP Modbus TCP, Modbus RTU MP-Bus Cloud |
| Control Signal Y | 2...10 V |
| Position Feedback U | 2...10 V |
| Running Time (Motor) | 90 s |
| Control Accuracy | ±5% |
| Min. Controllable Flow | 1% of V'nom |
| Manual Override | external push button |
| Servicing | maintenance-free |
| Degree of Protection NEMA/UL | NEMA 4 |
| Enclosure | UL Enclosure Type 4 |
| Ambient Temperature | -40...122°F [-40...50°C] |
| Ambient Humidity | Max. 100% RH |
| Storage Temperature | -40...176°F [-40...80°C] |
| Valve Body Material | Nickel-plated brass body |
| Stem | stainless steel |
| Seat | PTFE |
| Characterized Disc | TEFZEL® |
| Ball | stainless steel |
| O-ring | EPDM |
Documentation
Related Products
Frequently Asked Questions
What is the nominal flow rate of the Belimo EV125+ARX-E N4HT?
The EV125+ARX-E N4HT is rated 28.5 GPM nominal flow (V′nom) at a valve size of 1-1/4".
Does the Belimo EV125+ARX-E N4HT support BACnet natively?
Yes. BACnet/IP and BACnet MS/TP are integral to the actuator, alongside Modbus TCP, Modbus RTU and MP-Bus. No external protocol gateway is required.
What enclosure rating does the Belimo EV125+ARX-E N4HT carry?
NEMA 4 / UL Enclosure Type 4. Belimo does not publish an IEC/EN IP rating for this model.
What is the difference between the N4HT and N4HH versions?
The N4HT version cycles its internal heater on enclosure temperature. Both carry the same NEMA 4 rating; the difference is what triggers the heater.
Is the Belimo EV125+ARX-E N4HT fail-safe?
No. This model uses a non fail-safe actuator and holds its last position on loss of supply power. Specify a fail-safe actuator variant if the circuit must drive to a defined position.
Why might the EV125+ARX-E N4HT arrive with a gray actuator cover?
Belimo has advised that a supplier issue means some NEMA 4 actuator covers ship in gray rather than orange until further notice. Protective properties and product specifications are unchanged.
Belimo 5-Year Limited Warranty. Coverage is subject to Belimo's applicable Terms and Conditions of Sale and to any product-specific warranty requirements. See Section IX of the Belimo Energy Valve technical documentation for the full terms.
- Type:
- Energy Valve (PI-CCV)
- Valve Pattern:
- 2-Way
- Valve Size:
- 1-1/4 Inch
- GPM:
- 28.5
- Actuator Type:
- Non Fail-Safe
- Actuator Model:
- ARX-E
- Voltage:
- 24VAC/DC
- Communication:
- BACnet/Modbus/MP-Bus
- NEMA 4/4X:
- Yes
- Enclosure Heater:
- Thermostat
- Connection Type:
- NPT Female
