TF-24: Belimo Spring Return 24V

Submittal Form
SKU: Belimo TF-24 Category:


For modulation or On/Off control of dampers in HVAC systems. Actuator sizing should be done in accordance with the damper manufacturer’s specifications. The actuator is mounted directly to a damper shaft from 1/4” up to 1/2” in diameter by means of its universal clamp, 1/2” shaft centered at delivery. A crank arm and several mounting brackets are available for applications where the actuator cannot be direct coupled to the damper shaft. Control is floating point from a triac or relay, or On/Off from an auxiliary contact on a fan motor contactor, controller, or manual switch.

The TF 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 TF series provides 95° of rotation and is provided with a graduated position indicator showing 0 to 95°. The TF24-3(-S) US uses a brushless DC motor which is controlled by an Application Specific Integrated Circuit (ASIC) and a microprocessor. The microprocessor provides the intelligence to the ASIC to provide a constant
rotation rate. The ASIC monitors and controls the brushless DC motor’s rotation and provides a digital rotation sensing function to prevent damage to the actuator in a stall condition. 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 TF24-3-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 TF24-3-S US is double insulated so an electrical ground is not necessary.

Additional information

Power Supply

24 VAC ± 20%, 50/60 Hz

Power Consumption (Running)

2.5 W

Power Consumption (Holding)

1 W

Transformer Sizing

4 VA (class 2 power source)

Electrical Connection

3 ft, 18 ga. plenum rated cable
1/2" conduit connector

Overload Protection

electronic throughout 0 to 95° rotation

Input Impedance

Input impedance 1000 Ω (0.6w) control inputs

Electrical Protection

actuators are double insulated

Angle of Rotation

max 95°, adjust. with mechanical stop


18 in-lb [2 Nm]

Direction of Rotation (Motor)

reversible with cw/ccw mounting

Direction of Rotation (Spring)

reversible with built-in switch

Position Indication

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

Running Time (Motor)

Running time motor 95 sec constant, independent of load

Running Time (Spring)

< 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]

Storage Temperature

-40°F to 176°F [-40°C to 80°C]


NEMA type 2 / IP42, UL enclosure type 2

Housing Material


Angency Listings†

cULus acc. to UL60730-1A/-2-14, CAN/CSA
E60730-1:02, CE acc. to 2004/108/EC,
(and 2006/95/EC for -S versions)

Noise Level (MAX) (Running)

< 35 db (A)

Noise Level (MAX) (Spring Return)

62 dB (A)


maintenance free

Quality Standard

ISO 9001


1.4 lbs (0.6 kg)

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