The Belimo EFCX24-S N4 is a high-torque spring-return (fail-safe) damper actuator delivering 270 in-lb [30 Nm] of torque with two-position on/off control 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 EFX platform for large commercial HVAC dampers that must fail to a safe position. As an EFC fast-acting model it drives to its fail-safe position in about 10 seconds. Two built-in SPDT auxiliary switches signal damper position or interlock equipment. The watertight NEMA 4 housing suits washdown and outdoor service.
Specifications sourced from the official Belimo EFCX24-S N4 technical data sheet (rev 2025-12-24).
Overview
Belimo EF-Series actuators are high-torque spring-return drives for large commercial HVAC control dampers requiring fail-safe operation. The EFCX24-S N4 produces 270 in-lb [30 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 EFC variant is fast-acting, returning to its fail-safe position in roughly 10 seconds — useful where rapid damper closure matters. Two-position on/off control drives the damper open and the spring returns it on signal or power loss.
Best for
- Applications needing rapid (~10 s) fail-safe damper closure
- Large commercial HVAC dampers needing fail-safe (spring-return) operation
- High-torque damper and louver control (270 in-lb)
- Outdoor-air, mixing-box and economizer dampers that must fail safe
- Washdown / wet / outdoor locations (NEMA 4)
- End-position signaling or equipment interlock (2x SPDT)
Key Features
Fast-Acting Fail-Safe
Returns the damper to its fail-safe position in about 10 seconds on power loss — roughly twice as fast as a standard EF actuator, for applications needing rapid closure.
270 in-lb High Torque
Sized for large commercial dampers; direct-couples to round or square damper shafts up to 1.05 in. with a universal clamp.
On/Off Control
Accepts two-position on/off control from a controller, relay or switch.
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.
Two SPDT Aux Switches
Two built-in SPDT auxiliary switches (1 mA-3 A) signal damper end position or interlock other equipment.
Technical Specifications
| Parameter | Specification |
|---|---|
| Manufacturer | Belimo |
| Part Number | EFCX24-S N4 |
| Actuator Type | Spring-Return (Fail-Safe) Damper Actuator — fast-acting |
| Nominal Voltage | AC/DC 24 V |
| Nominal Frequency | 50/60 Hz |
| Power Consumption (Running) | 9.5 W |
| Transformer Sizing | 16 VA |
| Torque (Motor & Spring) | 270 in-lb [30 Nm] (minimum, full rotation) |
| Control Signal | On/Off (two-position, 1 or 3-wire) |
| 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) | 75 s / 90° |
| Spring Return Time | about 10 s (fast-acting) for fail-safe |
| Behavior on Power Loss | Spring returns damper to fail-safe position |
| Fail-Safe Direction | Reversible (CW/CCW) by mounting orientation |
| Auxiliary Switch | 2x SPDT, 1 mA-3 A (0.5 A inductive), DC 5 V-AC 250 V |
| 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 4 / UL Type 4 (watertight) |
| Ambient Temperature | -22 to 122°F [-30 to 50°C] |
| Agency Listing | cULus (UL60730-1A/-2-14, CAN/CSA) |
| Quality Standard | ISO 9001 |
| Weight | 10 lb [4.7 kg] |
| Warranty | 5 Years |
Documentation
Related Products
Accessories & Mounting
Common Belimo accessories for mounting, linkage, signaling and powering the EFCX24-S 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 EFCX24-S N4?
The Belimo EFCX24-S N4 is a high-torque spring-return (fail-safe) damper actuator for large commercial HVAC dampers. It produces 270 in-lb [30 Nm] of torque, uses two-position on/off control 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 4.
Is the EFCX24-S N4 a spring-return (fail-safe) actuator?
Yes. The EFCX24-S 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 EFCX24-S N4 on power loss?
Its internal spring returns the damper to the fail-safe position in about 10 s (fast-acting). The fail-safe direction (CW or CCW) is set by the mounting orientation.
What is the difference between EFC and EF actuators?
EFC actuators are fast-acting: they return to the fail-safe position in about 10 seconds, roughly twice as fast as a standard EF actuator (under 20 seconds). They are otherwise the same 270 in-lb spring-return actuator.
How much torque does the EFCX24-S N4 provide?
It delivers 270 in-lb [30 Nm] of minimum running and spring-return torque, sizing it for large commercial dampers.
What shaft sizes does the EFCX24-S 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-EFB) and brackets (ZG-120, ZG-JSA-3) are available.
What control signal does the EFCX24-S N4 use?
It uses two-position on/off control. On/Off control is driven from a controller, relay or switch.
Does the EFCX24-S N4 have auxiliary switches?
Yes. It has two built-in SPDT auxiliary switches (rated 1 mA to 3 A) for end-position signaling or interlocking other equipment.
Is the EFCX24-S N4 suitable for outdoor or wet locations?
Yes. The EFCX24-S N4 has a watertight NEMA 4 / UL Type 4 housing suitable for washdown, wet and outdoor installations.
How do you manually position the EFCX24-S N4?
Use the supplied 5 mm hex crank (3/16" Allen) to wind the actuator by hand for setup or service.
Is the Belimo EFCX24-S N4 available from an authorized Belimo distributor?
Yes. ZOT Supply is an authorized Belimo distributor and carries the EFCX24-S N4. Every unit ships factory new with Belimo's full 5-year warranty and application support.
- Actuator Type:
- Spring-Return (Fail-Safe)
- Torque:
- 270 in-lb
- Control Signal:
- On/Off
- Voltage:
- 24 VAC/DC
- Auxiliary Switch:
- 2x SPDT
- Enclosure:
- NEMA 4
- Series:
- EFX
- Fail-Safe Speed:
- Fast (~10 s)
