027 04299 004 York Damper Actuator (NFB24-SR)

Overview

The York 027 04299 004 (Belimo NFB24-SR) is a high-performance, spring-return damper actuator designed for the proportional modulation of dampers in HVAC systems. Providing a minimum of 90 in-lb of torque, this direct-coupled actuator ensures reliable fail-safe operation by automatically returning the damper to a safe position during a power loss. It is engineered with a brushless DC motor and microprocessor control, offering precise positioning and constant torque output for commercial building automation and air handling applications.

Features

• True spring-return mechanism provides reliable fail-safe positioning and positive close-off for airtight dampers.
• Brushless DC motor technology ensures a long service life, maintenance-free operation, and precise control.
• Electronic overload protection throughout the 0 to 95 degree rotation prevents motor damage without the need for mechanical limit switches.
• Manual override is integrated via a 5 mm hex crank, allowing for manual positioning and easy system testing during installation or maintenance.
• Symmetrical design allows for simple clockwise or counter-clockwise mounting to determine the fail-safe direction.
• Visual position indicator provides clear mechanical status of the damper’s rotation angle.

Specifications

• Torque: 90 in-lb (10 Nm)
• Power Supply: AC 24 V, 50/60 Hz; DC 24 V
• Power Consumption: 3.5 W (Running), 2.5 W (Holding)
• Transformer Sizing: 6 VA
• Control Signal: 2-10 VDC (Default); 4-20 mA (with 500 ohm resistor)
• Feedback Signal: 2-10 VDC
• Running Time (Motor): 95 seconds
• Running Time (Fail-Safe): <20 seconds at ambient temperatures
• Angle of Rotation: Max 95 degrees, adjustable with mechanical end stops
• Enclosure Rating: NEMA 2, IP54
• Ambient Temperature Range: -22 to 122 degrees Fahrenheit (-30 to 50 degrees Celsius)

Applications

• Designed for the proportional modulation of dampers in typical commercial HVAC air handling units.
• Ideal for control of dampers up to approximately 22 square feet, depending on damper construction and air pressure.
• Suitable for use in air plenums (UL 2043 compliant) in building automation systems.
• Frequently utilized in retrofit projects to replace older, less efficient pneumatic or electric actuators.
• Applicable for any HVAC system requiring a reliable fail-safe return to a normal position upon loss of power.