LF-24: Belimo Spring Return 24V

Submittal Form
SKU: Belimo LF-24 Category: Tag:


For On/Off, fail-safe control of dampers in HVAC systems. Actuator sizing should be done in accordance with the damper manufacturer’s specifications. Control is On/Off from an auxiliary contact, digital output, or a manual switch. The actuator is mounted directly to a damper shaft from 3/8” up to 1/2” in diameter by means of its universal clamp, 1/2” shaft centered at delivery. For shafts up to 3/4” use K6-1 accessory. A crank arm and several mounting brackets are available for applications where the actuator cannot be direct coupled to the damper shaft.

The LF series actuators provide true spring return operation for reliable fail-safe application and positive close off on air tight dampers. The spring return system provides consistent torque to the damper with, and without, power applied to the actuator. The LF series provides 95° of rotation and is provided with a graduated position indicator showing 0° to 95°. The actuator may be stalled anywhere in its normal rotation without the need of mechanical end switches. Power consumption is reduced in holding mode. The LF24-S US version is provided with 1 built in auxiliary switch. This SPDT switch is provided for safety interfacing or signaling, for example, for fan startup. The switching function is adjustable between 0° and 95°. The auxiliary switch in the LF24-S is double insulated so an electrical ground connection is not necessary.

Additional information

Power Supply

24 VAC ± 20% 50/60 Hz
24 VDC ± 10%

Power Consumption (Running)

5 W

Power Consumption (Holding)

2.5 W

Transformer Sizing

7 VA (class 2 power source)

Electrical Connection

3 ft. 18 ga. appliance cable
1/2” conduit connector

Overload Protection

electronic throughout 0 to 95° rotation

Angle of Rotation

max. 95°, adjust. with mechanical stop


max. 95°, adjust. with mechanical stop

Direction of Rotation

reversible with cw/ccw mounting

Position Indication

visual indicator, 0° to 95°
(0° is spring return position)

Motor Running Time (Nominal)

< 40 to 75 sec

Spring Running Time (Nominal)

< 25 sec @-4°F to 122°F [-20°C to 50°C]
< 60 sec @-22°F [-30°C]


5 to 95% RH non-condensing

Ambient Temperature

-22°F to 122°F [-30°C to 50°C]


-40°F to 176°F [-40°C to 80°C]


NEMA type 2 / IP54

Housing Material

NEMA type 2 / IP54

Agency Listings†

cULus acc. to UL 873 and
CAN/CSA C22.2 No. 24-93

Running Noise Level (Max)

< 50 db (A)

Spring Return Noise Level (Max)

62 dB (A)


maintenance free

Quality Standard

ISO 9001