The Belimo AFB24-MFT is a spring-return (fail-safe) damper actuator delivering 180 in-lb [20 Nm] of torque with field-programmable multi-function (MFT) control that ships configured for 2-10 VDC by default on 24 VAC/DC power. It direct-couples to damper shafts up to 1.05 in. diameter and drives to a mechanical fail-safe position on power loss, making it a proven member of the AFB spring-return platform for commercial HVAC damper control. Functionally it matches the modulating AFB/AFX-SR, with the added flexibility to field-select other control signals and ranges.
Specifications sourced from the official Belimo AFB24-MFT technical data sheet (rev 2023-03-13).
Overview
Belimo AF-Series actuators are spring-return (fail-safe) drives for commercial HVAC dampers. The AFB24-MFT produces 180 in-lb [20 Nm] of torque, mounts directly to the damper shaft, and On loss of power the spring drives the damper to its defined fail-safe position within the rated fail-safe time. It ships configured for 2-10 VDC modulating control — the same behavior as the SR model — but its Multi-Function Technology lets you field-select other control signals, operating ranges and feedback (on/off, floating point, PWM, variable VDC) without changing the part number.
Best for
- Modulating control with 2-10 VDC default output
- Retrofit / replacement where the existing signal must be matched in the field
- One stocked part covering multiple control-signal specs
Key Features
True Spring Return Fail-Safe
Constant-torque spring drives the damper to a defined safe position on power loss — no mechanical end switches required, and positive close-off on air-tight dampers.
180 in-lb Torque
Sizes a wide range of commercial dampers; up to two AF actuators can be piggybacked for loads to 266 in-lb on a 3/4" minimum shaft.
MFT — 2-10 VDC by Default
Ships configured for 2-10 VDC modulating control (same as the SR model). Multi-Function Technology lets you field-select other signals and ranges — variable VDC, on/off, floating point or PWM — under one part number.
Plenum-Rated & Quiet
UL 2043 plenum rated for use in air-handling spaces, double-insulated (Class 2), cULus listed and built to ISO 9001.
Technical Specifications
| Parameter | Specification |
|---|---|
| Manufacturer | Belimo |
| Part Number | AFB24-MFT |
| Actuator Type | Spring-Return (Fail-Safe) Damper Actuator |
| Nominal Voltage | AC/DC 24 V |
| Nominal Voltage Range | AC 19.2-28.8 V / DC 21.6-28.8 V |
| Nominal Frequency | 50/60 Hz |
| Power Consumption (Running) | 7.5 W |
| Power Consumption (Holding) | 3W |
| Transformer Sizing | 10 VA |
| Torque | 180 in-lb [20 Nm] |
| Control Signal | Modulating, field-programmable (MFT) — ships configured for 2-10 VDC by default |
| Default Operating Range | 2-10 VDC (4-20 mA with ZG-R01 resistor) |
| Selectable Operating Modes | 2-10 VDC (default), variable VDC, On/Off, Floating Point, PWM |
| Variable Range | Start point 0.5-30 V, end point 2.5-32 V |
| Position Feedback (U) | 2-10 VDC default, VDC variable (max. 0.5 mA) |
| Angle of Rotation | 95° (adjustable end stop 35-95°) |
| Running Time (Motor) | 150 s / 90° |
| Running Time (Fail-Safe) | <20 s @ -4 to 122°F [-20 to 50°C]; <60 s @ -22°F [-30°C] |
| Manual Override | 5 mm hex crank (3/16" Allen), supplied |
| Direction of Motion | Selectable CW/CCW |
| Position Indication | Mechanical |
| Electrical Connection | 18 AWG appliance 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 2 / IP54 / UL Type 2 |
| Housing Material | UL94-5VA |
| Ambient Temperature | -22 to 122°F [-30 to 50°C] |
| Storage Temperature | -40 to 176°F [-40 to 80°C] |
| Agency Listing | cULus (UL60730-1A / -2-14, CAN/CSA) |
| Quality Standard | ISO 9001 |
| Plenum Rated | UL 2043 (suitable for air plenums) |
| Weight | 4.1 lb [1.9 kg] |
| Warranty | 5 Years |
Documentation
Related Products
Accessories & Mounting
Common Belimo accessories for mounting, linkage, signaling and powering the AFB24-MFT, 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 AFB24-MFT?
The Belimo AFB24-MFT is a spring-return (fail-safe) damper actuator for commercial HVAC. It produces 180 in-lb [20 Nm] of torque, uses field-programmable MFT control (configured for 2-10 VDC by default) on 24 VAC/DC power, and drives the damper to a mechanical fail-safe position on loss of power. Its housing is rated NEMA 2 / IP54 / UL Type 2.
How does the AFB24-MFT fail safe on power loss?
The AFB24-MFT stores energy in a return spring during normal operation. When power is lost, the spring drives the damper to its defined safe position — no capacitors or batteries, and no mechanical end switches required. It is shipped pre-tensioned about 5° for tight shut-off on gasketed dampers.
What torque does the AFB24-MFT provide and what shaft sizes does it fit?
It delivers 180 in-lb [20 Nm] and direct-couples to round or square damper shafts up to 1.05 in. diameter using its universal clamp. Up to two AF actuators can be piggybacked for loads to 266 in-lb on a 3/4 in. minimum shaft.
What control signal does the AFB24-MFT use?
It uses field-programmable MFT control (configured for 2-10 VDC by default). Because it is MFT, you can field-select other modes (variable VDC, on/off, floating point, PWM) and ranges without changing the part number.
What is the running time of the AFB24-MFT?
Motor running time is about 150 seconds for 90° of travel, and the spring-return fail-safe time is under 15 seconds at normal temperatures (under 60 seconds at -22°F [-30°C]).
Is the AFB24-MFT the same as the SR (2-10 VDC) version?
Functionally yes — it ships configured for 2-10 VDC modulating control, identical to the SR model. The difference is that Multi-Function Technology lets you field-select other control signals, operating ranges and feedback, so one part number covers many specifications. Choose MFT when you need that flexibility; choose SR for a fixed 2-10 VDC application.
Is the AFB24-MFT UL listed for damper control?
Yes. The AFB24-MFT is cULus listed to UL60730 and CAN/CSA, is double-insulated (Class 2), and is UL 2043 plenum-rated for installation in air-handling spaces.
Is the Belimo AFB24-MFT available from an authorized Belimo distributor?
Yes. ZOT Supply is an authorized Belimo distributor and carries the AFB24-MFT. Every unit ships factory-new with Belimo's full 5-year warranty and application support from our team.
- Actuator Type:
- Spring Return
- Torque:
- 180 in-lb
- Control Signal:
- Programmable (MFT)
- Voltage:
- 24 VAC/DC
- Auxiliary Switch:
- No
- NEMA 4X Enclosure:
- No
- Series:
- AFB
- Feedback Signal:
- 2-10 VDC
