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.