Damper Actuators For HVAC Systems What You Need To Know

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Damper actuators are crucial components in HVAC systems that control the position of dampers to regulate airflow. A damper actuator is a device that receives a control signal and provides the power to reposition a damper to the desired setpoint.

Damper actuators come in two main types – pneumatic actuators, which use air pressure, and electric actuators, which use electric power. In an HVAC system, damper actuators precisely modulate damper position in response to thermostats, building automation systems, or duct static pressure controller demands. Moreover, this allows control over the amount of heated/cooled air delivered to different zones in a building.

In this article, we will provide an overview of the different types of damper actuators used in HVAC systems. We will compare pneumatic and electric actuators, discuss key features to consider when selecting an actuator, and provide tips for proper sizing, installation, and maintenance. By the end, readers will have a solid understanding of damper actuator applications, selection criteria, and best practices for integration into HVAC systems.

Damper Actuators

Types of Damper Actuators

Pneumatic damper actuators use air pressure to move a piston or diaphragm to reposition a damper. They receive a 3-15 psi control signal from the building automation system and amplify it to produce up to 60 lb-ft of torque. Pneumatic actuators excel in dirty, humid environments since they don’t use electricity. However, they require plant air compressors and extensive tubing runs for control signals.

Electric damper actuators use an electric motor and gears to drive the damper. A 24 VAC control signal powers Belimo’s electric actuators and provides precision control with high torque capabilities of up to 443 lb-ft. Electric actuators are more energy efficient and offer better accuracy than pneumatic versions. They’re also much easier to install and maintain without the need for compressors and tubing.

Belimo damper actuators offer models to suit any HVAC damper application. Their brushless DC motor actuators are programmable for control signal ranges, timing, fail-safe positions, and more. Belimo’s actuators can communicate feedback and diagnostics over digital networks. Compared to pneumatic actuators, Belimo electric actuators provide higher precision control, lower ownership costs, and simpler installation – making them the preferred choice for modern HVAC systems.

HVAC Maintenance Tips

Damper Actuator Features

Selecting a damper actuator with proper torque capacity is crucial for correct damper control. Insufficient torque will lead to hunting or the inability to drive a damper fully open/closed. Belimo’s actuators offer a wide range of torques from 35 in-lbs up to 443 ft-lbs to properly handle damper sizes from a couple of square feet up to over 100 square feet.

Additionally, actuator speed is also essential. Fast 90-second actuators allow for rapid air balancing and HVAC adjustment. Slow actuators up to 240 seconds are best for stable temperature control in occupied spaces. Belimo offers adjustable timing to optimize actuator speeds.

The fail-safe operation ensures dampers move to a known safe position during a power failure. You can set Belimo actuators for fail, open, or closed for fire, smoke, or freeze protection.

Versatile mounting options enable flexible installation. Direct-coupled actuators mount directly to a damper shaft for tight control. Jackshaft and linkage arm assemblies allow remote mounting. Belimo makes universal brackets, crank arms, and couplings for adaptation to any assembly.

Finally, actuators must be designed for the control signal provided by the HVAC system. Belimo offers models for analog 2-10VDC, 4-20mA, and 0-10VDC signals, as well as digital network communication over Belimo MP-Bus, MODBUS, and more.

Furthermore, this flexibility ensures compatibility with any automation system. With attention to these key features – torque, speed, fail-safe mode, mounting scheme, and control signal. Moreover, you can select the ideal damper actuator for optimal HVAC performance in any application.

Damper Actuators

Sizing Considerations

Properly sizing a damper actuator is crucial for optimum HVAC performance. Torque capacity must match damper size and sealing requirements. Siemens damper actuators range from 7 in-lbs up to 265 ft-lbs to accommodate any application. Speed should align with occupancy comfort – fast for air balancing, slow for stable temp control.

Siemens offers adjustable timing from 150 seconds to 240 seconds. Operating temperature range must account for ambient conditions – Siemens actuators function from -22°F to +122°F. Control signal availability is critical – Siemens makes models for analog, digital, and wireless control.

Finally, budget plays a role – Siemens provides quality, cost-effective actuator solutions ranging from $50 up to $500 list price. By factoring in torque, speed, temperature, control signal, and budget requirements, you can select the ideal Siemens damper actuator to maximize HVAC efficiency and comfort.

Installing and Maintaining Damper Actuators

Correct installation and maintenance are essential for proper damper actuator function. Always follow manufacturer instructions for mounting, wiring, linkage set-up, and control programming during installation. Perform annual inspections to check for loose fasteners, worn linkage attachments, dirt/debris buildup, and cable/tubing damage.

Additionally, confirm that programmed control parameters have not drifted over time. Troubleshoot issues like hunting, slow response, or failure to open/close by checking for power supply problems, loose mechanical linkages, blocked air passages, or faulty components. With proper installation, routine maintenance, and quick troubleshooting, they will provide reliable, precise HVAC airflow control.


Damper actuators are critical components that modulate airflow in HVAC systems. As discussed, key considerations when selecting damper actuators include having proper torque for the damper size, adjustable timing to meet occupancy needs, fail-safe operation for protection, flexible mounting options, and control signal compatibility.

More importantly, following manufacturer guidance for installation, along with routine maintenance and troubleshooting, will ensure maximum performance and service life. Properly applying them improves comfort, reduces operating costs, and extends equipment lifespan. Consult manufacturers like Belimo and Siemens for additional damper actuator selection resources and technical support.

HVAC Replacement

Owning a home means significant responsibilities. And when it’s time for an HVAC replacement, there’s essential information you need to know first. The average home has several different vital systems that work around the clock. 

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