The Belimo LMX24-3-S is a compact non-spring-return damper actuator delivering 45 in-lb [5 Nm] of torque with on/off and floating-point control on AC/DC 24 V power. It direct-couples to round or square damper shafts from 1/4 in. to 5/8 in. (up to 3/4 in. with an accessory clamp) and is non-fail-safe, with no spring return, making it part of Belimo's configurable LMX platform for small to mid-size commercial HVAC dampers. A built-in SPDT auxiliary switch signals damper position or interlocks equipment.
Specifications sourced from the official Belimo LMX24-3-S technical data sheet (rev 2023-03-10).
Overview
Belimo LM-Series actuators are compact non-spring-return drives for small and mid-size commercial HVAC dampers — they position the damper under power and have no spring-return fail-safe function. The LMX24-3-S produces 45 in-lb [5 Nm] and mounts directly to round or square damper shafts from 1/4 in. to 5/8 in. (up to 3/4 in. with an accessory clamp). Two-position on/off and 3-wire floating-point control position the damper from a controller or switch.
Best for
- Compact non-spring-return damper control where fail-safe return is not required
- Small to mid-size damper and louver positioning (45 in-lb)
- Direct shaft mount, 1/4-5/8 in. (to 3/4 in. with accessory clamp)
- End-position signaling or equipment interlock
Key Features
Non-Spring-Return Design
No fail-safe spring return. Belimo does not publish a defined position on loss of power for this model; specify a spring-return actuator where a fail-safe position is required.
45 in-lb Torque
Sized for small and mid-size dampers; direct-couples to round or square damper shafts from 1/4 in. to 5/8 in. (up to 3/4 in. with an accessory clamp).
On/Off & Floating Point
Accepts two-position on/off or 3-wire floating-point control from a controller, relay or switch.
Built-In SPDT Aux Switch
One SPDT auxiliary switch (1 mA-3 A) signals damper end position or interlocks other equipment.
cULus Listed & Quiet
cULus listed, ISO 9001 built, UL 2043 plenum-rated for long, maintenance-free service.
Technical Specifications
| Parameter | Specification |
|---|---|
| Manufacturer | Belimo |
| Part Number | LMX24-3-S |
| Actuator Type | Non-Spring-Return (Non Fail-Safe) Damper Actuator |
| Nominal Voltage | AC/DC 24 V |
| Nominal Frequency | 50/60 Hz |
| Power Consumption (Running) | 1.5 W |
| Transformer Sizing | 2.5 VA |
| Torque | 45 in-lb [5 Nm] |
| Control Signal | On/Off and Floating Point (3-wire) |
| Shaft Range | 1/4 in. to 5/8 in. (to 3/4 in. with accessory clamp) |
| Angle of Rotation | Max. 95° (adjustable mechanical stop) |
| Running Time (Motor) | 95 s / 90° |
| Running Time Note | constant, independent of load |
| Variable Running Time | 35, 45, 60, 150 s |
| Behavior on Power Loss | Non fail-safe — no fail-safe spring return function |
| Auxiliary Switch | 1x SPDT, 1 mA-3 A (0.5 A inductive), DC 5 V-AC 250 V |
| Manual Override | External push button |
| Direction of Motion | Selectable with 0/1 switch |
| Electrical Connection | 18 AWG plenum cable, 3 ft [1 m], 1/2 in. NPT conduit connector |
| Overload Protection | Electronic, full 0-95° rotation |
| Power Source | UL Class 2 Supply |
| Auxiliary Switch Insulation | Built-in SPDT auxiliary switch is double insulated; no electrical ground connection required |
| Enclosure Rating | NEMA 2 / UL Type 2 / IP54 |
| Ambient Temperature | -22 to 122°F [-30 to 50°C] |
| Agency Listing | cULus (UL60730-1A / -2-14, CAN/CSA) |
| Quality Standard | ISO 9001 |
| Plenum Rated | UL 2043 (suitable for air plenums) |
| Weight | 0.62 lb [0.28 kg] |
| Warranty | 5 Years |
Documentation
Related Products
Accessories & Mounting
Common Belimo accessories for mounting, linkage, signaling and powering the LMX24-3-S, drawn from the actuator datasheet. All are stocked by ZOT Supply as an authorized Belimo distributor.
Mounting & Linkage
Electrical Add-Ons
Enclosures & Weather Shields
Frequently Asked Questions
What is the Belimo LMX24-3-S?
The Belimo LMX24-3-S is a compact non-spring-return (non-fail-safe) damper actuator for commercial HVAC. It produces 45 in-lb [5 Nm] of torque, uses on/off and floating-point control on AC/DC 24 V power. It is non-fail-safe: Belimo does not publish a defined position on loss of power for this model. Its housing is rated NEMA 2 Enclosure UL Enclosure Type 2.
Is the LMX24-3-S a spring-return (fail-safe) actuator?
No. The LMX24-3-S is non-spring-return: it has no fail-safe spring, so it will not drive to a predetermined position when power is lost. Where a defined position on power loss is required, select a spring-return actuator sized to the damper manufacturer's specifications.
What happens to the LMX24-3-S when power is lost?
There is no spring return, so the actuator does not drive itself to a fail-safe position. Belimo's datasheet for this model does not publish a defined power-loss position; if your sequence depends on a specific position during a power failure, specify a spring-return actuator.
What shaft sizes does the LMX24-3-S fit?
It direct-couples to round or square damper shafts from 1/4 in. to 5/8 in. (up to 3/4 in. with an accessory clamp) using its universal clamp.
What control signal does the LMX24-3-S use?
It uses on/off and floating-point control. On/Off and 3-wire floating-point control are driven from a controller, relay or switch.
What is the running time of the LMX24-3-S?
Motor running time is 95 s / 90°. Belimo also publishes variable running-time values of 35, 45, 60, 150 s.
Does the LMX24-3-S have an auxiliary switch?
Yes. It has one built-in SPDT auxiliary switch (rated 1 mA to 3 A) for end-position signaling or interlocking other equipment.
What is the difference between the Belimo LMX24-3-S and the LMB24-3-S?
Both are non-spring-return actuators of the same torque class. Their published specifications are not identical: LMX24-3-S and LMB24-3-S differ on weight 0.62 lb vs 0.86 lb; electrical connection 18 AWG plenum cable with 1/2 in. conduit connector vs 18 AWG plenum cable with 1/2 in. NPT conduit connector. LMX24-3-S additionally publishes a variable running time of 35, 45, 60, 150 s; LMB24-3-S does not publish this field. Both datasheets state NEMA 2 / IP54 protection. Verify the exact control, running time, electrical, enclosure and mounting requirements before substituting one for the other.
Is the Belimo LMX24-3-S available from an authorized Belimo distributor?
Yes. ZOT Supply is an authorized Belimo distributor and carries the LMX24-3-S. Every unit ships factory new with Belimo's full 5-year warranty and application support.
- Actuator Type:
- Non-Fail-Safe
- Torque:
- 45 in-lb
- Control Signal:
- On/Off
- Voltage:
- 24 VAC/DC
- Auxiliary Switch:
- 1x SPDT
- Series:
- LM
