The Belimo NFX24-MFT N4 is a robust spring-return (fail-safe) damper actuator delivering 90 in-lb [10 Nm] of torque with field-programmable MFT control that ships set for 2-10 VDC by default on AC/DC 24 V power. It direct-couples to round or square damper shafts up to 1.05 in. with a universal clamp and is part of Belimo's configurable NFX platform for commercial HVAC dampers that must fail to a safe position. On power loss the internal spring drives the damper to its fail-safe position in under 20 seconds. The watertight NEMA 4 housing suits washdown and outdoor service.
Specifications sourced from the official Belimo NFX24-MFT N4 technical data sheet (rev 2025-12-23).
Overview
Belimo EF-Series actuators are spring-return drives for commercial HVAC control dampers requiring fail-safe operation. The NFX24-MFT N4 produces 90 in-lb [10 Nm] and mounts directly to round or square damper shafts up to 1.05 in. with its universal clamp (a crank arm and brackets are available for jackshaft and linkage applications). The fail-safe direction is reversible by CW/CCW mounting, and a 5 mm hex crank allows manual positioning. The spring returns the damper to its fail-safe position in under 20 seconds when power is removed. It ships set for 2-10 VDC modulating control, and Multi-Function Technology lets you field-select other signals, ranges and feedback under one part number.
Best for
- Modulating control with field-selectable signal (2-10 VDC default)
- Medium-torque damper and louver control (90 in-lb)
- Outdoor-air, mixing-box and economizer dampers that must fail safe
- Washdown / wet / outdoor locations (NEMA 4)
Key Features
Spring-Return Fail-Safe
A mechanical spring drives the damper to a safe position on power or signal loss (under 20 seconds), with no external power required to fail safe.
90 in-lb Torque
Sized for mid-size commercial dampers; direct-couples to round or square damper shafts up to 1.05 in. with a universal clamp.
MFT — 2-10 VDC by Default
Ships set for 2-10 VDC modulating control. Field-select other signals and ranges under one part number.
Reversible Fail-Safe Direction
The spring-return (fail-safe) direction is selectable clockwise or counterclockwise simply by mounting orientation.
Manual Override Crank
A supplied 5 mm hex crank (3/16" Allen) lets you position the damper by hand for setup or service.
NEMA 4 Watertight
A watertight NEMA 4 / UL Type 4 housing suits washdown, wet and outdoor installations.
Technical Specifications
| Parameter | Specification |
|---|---|
| Manufacturer | Belimo |
| Part Number | NFX24-MFT N4 |
| Actuator Type | Spring-Return (Fail-Safe) Damper Actuator |
| Nominal Voltage | AC/DC 24 V |
| Nominal Frequency | 50/60 Hz |
| Power Consumption (Running) | 6.5 W |
| Torque (Motor & Spring) | 90 in-lb [10 Nm] (minimum, full rotation) |
| Control Signal | Modulating, field-programmable (MFT) — ships set for 2-10 VDC by default |
| Selectable Modes | 2-10 VDC (default), variable VDC, On/Off, Floating Point, PWM |
| Position Feedback (U) | 2-10 VDC default (max. 1 mA) |
| Shaft Range | Up to 1.05 in. [26.7 mm] via universal clamp; crank arm available |
| Angle of Rotation | 95° (adjustable mechanical stops) |
| Running Time (Motor) | 150 s / 90° |
| Spring Return Time | < 20 s (< 60 s below -22°F) for fail-safe |
| Behavior on Power Loss | Spring returns damper to fail-safe position |
| Fail-Safe Direction | Reversible (CW/CCW) by mounting orientation |
| Manual Override | 5 mm hex crank (3/16" Allen), supplied |
| Electrical Connection | 18 AWG plenum cable, 3 ft [1 m], 1/2" NPT conduit connector |
| Overload Protection | Electronic, full 0-95° rotation |
| Electrical Protection | Double insulated (Class 2) |
| Enclosure Rating | NEMA 4X / UL Type 4X (watertight, corrosion-resistant) |
| Ambient Temperature | -22 to 122°F [-30 to 50°C] |
| Agency Listing | cULus (UL60730-1A/-2-14, CAN/CSA) |
| Quality Standard | ISO 9001 |
| Weight | 9.4 lb [4.3 kg] |
| Warranty | 5 Years |
Documentation
Related Products
Accessories & Mounting
Common Belimo accessories for mounting, linkage, signaling and powering the NFX24-MFT N4, drawn from the actuator datasheet. All are stocked by ZOT Supply as an authorized Belimo distributor.
Mounting & Linkage
Electrical Add-Ons
Frequently Asked Questions
What is the Belimo NFX24-MFT N4?
The Belimo NFX24-MFT N4 is a robust spring-return (fail-safe) damper actuator for commercial HVAC dampers. It produces 90 in-lb [10 Nm] of torque, uses field-programmable MFT control (set for 2-10 VDC by default) on AC/DC 24 V power, and on power loss its spring drives the damper to a fail-safe position. Its housing is rated NEMA 4X.
Is the NFX24-MFT N4 a spring-return (fail-safe) actuator?
Yes. The NFX24-MFT N4 is spring-return: a mechanical spring drives the damper to its fail-safe position when power or the control signal is lost — no external power is needed to fail safe.
What happens to the NFX24-MFT N4 on power loss?
Its internal spring returns the damper to the fail-safe position in < 20 s (< 60 s below -22°F). The fail-safe direction (CW or CCW) is set by the mounting orientation.
How much torque does the NFX24-MFT N4 provide?
It delivers 90 in-lb [10 Nm] of minimum running and spring-return torque, sizing it for mid-size commercial dampers.
What shaft sizes does the NFX24-MFT N4 fit?
It direct-couples to round or square damper shafts up to 1.05 in. using its universal clamp. For jackshafts or off-shaft mounting, a crank arm (KH-AFB) and brackets (ZG-100, ZG-118) are available.
What control signal does the NFX24-MFT N4 use?
It uses field-programmable MFT control (set for 2-10 VDC by default). Because it is MFT, you can field-select other modes (variable VDC, on/off, floating point, PWM) without changing the part number.
Is the NFX24-MFT N4 suitable for outdoor or wet locations?
Yes. The NFX24-MFT N4 has a watertight NEMA 4 / UL Type 4 housing suitable for washdown, wet and outdoor installations.
Is the NFX24-MFT N4 the same as the SR (2-10 VDC) version?
Functionally yes — it ships set for 2-10 VDC modulating control, identical to the SR model. MFT simply lets you field-select other signals and ranges, so one part number covers many specifications.
How do you manually position the NFX24-MFT N4?
Use the supplied 5 mm hex crank (3/16" Allen) to wind the actuator by hand for setup or service.
Is the Belimo NFX24-MFT N4 available from an authorized Belimo distributor?
Yes. ZOT Supply is an authorized Belimo distributor and carries the NFX24-MFT N4. Every unit ships factory new with Belimo's full 5-year warranty and application support.
- Actuator Type:
- Spring-Return (Fail-Safe)
- Torque:
- 90 in-lb
- Control Signal:
- Programmable (MFT)
- Voltage:
- 24 VAC/DC
- Auxiliary Switch:
- No
- Enclosure:
- NEMA 4X
- Series:
- NFX
- Feedback Signal:
- 2-10 VDC
