| Two-Position, Non-Spring Return | Outdoor-air, return-air, exhaust, and isolation dampers that only need open or closed operation. | Maintains its last position when power is removed. It does not automatically return to a safe position. | Usually an on/off electrical command, commonly through a relay or dedicated controller output. | Verify supply voltage, actuator torque, rotation direction, shaft dimensions, and end-switch requirements. | Requires correct mechanical linkage, adequate shaft engagement, and accessible wiring terminals. | Periodically inspect mounting, linkage alignment, damper movement, and electrical connections. | Simple open/closed control is sufficient. |
| Two-Position, Spring Return | Ventilation, smoke-control-related equipment, and dampers requiring a defined position during power loss. | Returns to its spring position when power is interrupted. The spring position must match the required fail-safe condition. | Normally an on/off command with a suitable power supply and, where needed, auxiliary position contacts. | Confirm spring direction, fail-safe position, torque under load, voltage, and required actuator run time. | Spring force can increase installation effort. The damper must not be obstructed in the return direction. | Test power-failure operation, inspect the spring-return mechanism, and verify full damper travel. | The damper must move to a defined position after power loss. |
| Modulating Actuator | Airflow, temperature, pressure, or indoor-air-quality control where the damper must hold intermediate positions. | Safety behavior depends on the selected model: non-spring return holds position, while spring return moves to its fail-safe position. | Common signals include 0–10 V DC or 2–10 V DC; some systems use three-point floating control. | Match the signal type, input/output range, controller configuration, feedback requirements, voltage, and torque. | Requires correct commissioning, actuator rotation setup, signal polarity, and damper position calibration. | Check feedback accuracy, linkage wear, command response, and calibration during scheduled HVAC service. | Precise airflow or pressure regulation is required. |
| Proportional Actuator with Position Feedback | Building automation systems that need both variable positioning and confirmation of actual damper position. | May provide useful position feedback, but feedback alone is not a fail-safe function. A spring-return design may be required for power-loss protection. | Typically a modulating command plus an auxiliary feedback signal, such as a proportional voltage output. | Confirm controller input/output compatibility, feedback range, common reference, supply voltage, and signal scaling. | Requires careful wiring separation, correct signal polarity, and commissioning against the actual damper angle. | Verify commanded versus actual position and inspect feedback wiring for loose or damaged connections. | The control system must verify damper position. |
| High-Torque Actuator | Large, sealed, opposed-blade, or high-resistance dampers that require greater driving force. | Can be either spring return or non-spring return. High torque does not automatically provide a fail-safe response. | Available with on/off, floating, or modulating control depending on the actuator design. | Calculate required torque using damper size, blade type, air velocity, pressure differential, seal friction, and manufacturer data. | Requires a rigid mounting arrangement and sufficient shaft strength. Avoid selecting torque solely from damper face area. | Inspect mounting hardware, shaft deformation, linkage condition, and signs of overheating or stalled operation. | Measured damper resistance exceeds the capacity of standard actuators. |
| Fire or Smoke Damper Actuator | Listed fire, smoke, or combination fire-and-smoke damper assemblies where life-safety performance is involved. | Must operate according to the complete listed damper assembly and applicable code requirements, often including automatic closure under specified conditions. | Control method varies by the approved assembly and may include supervisory contacts, relay control, or dedicated life-safety control equipment. | Use only an actuator approved or listed for the specific damper assembly. Verify temperature rating, closure time, torque, voltage, and required accessories. | Installation must follow the damper and actuator listing, approved mounting method, wiring requirements, and local code. | Requires documented periodic inspection and functional testing according to applicable codes, standards, and facility procedures. | Life-safety applications require project-specific approval and code verification. |
| Weather-Resistant or Outdoor Actuator | Rooftop units, outdoor-air intakes, louvers, and equipment exposed to moisture, dust, or temperature changes. | Safety response depends on the actuator configuration. Environmental protection does not determine fail-safe behavior. | May support on/off, floating, or modulating signals depending on the selected model. | Check enclosure or ingress protection rating, ambient temperature range, UV exposure, voltage, torque, and cable-entry method. | Use weatherproof conduit and glands where required. Prevent water from tracking along cables into the actuator enclosure. | Inspect seals, cable entries, corrosion, condensation, mounting security, and damper travel. | The actuator is installed in a harsh or exposed environment. |
| Fast-Running Actuator | Dampers that must reach their commanded position quickly for ventilation sequences or equipment protection. | Fast operation does not by itself provide fail-safe performance. Confirm whether spring return is required. | Often available for on/off or modulating control, subject to the controller’s output capability. | Verify required run time, control cycle frequency, torque throughout travel, supply capacity, and damper mechanical limits. | Ensure the damper can safely tolerate the operating speed without excessive noise, vibration, or mechanical impact. | Inspect stops, linkage, gears, noise, vibration, and repeated cycling performance. | Fast travel is necessary and the damper is mechanically suitable. |
| Low-Power Actuator | Distributed terminal units, small dampers, and systems where available electrical capacity is limited. | Safety behavior depends on whether the unit is spring return or non-spring return, not on its low power consumption. | May use on/off, floating, or low-voltage modulating control. | Confirm operating current, inrush current, transformer capacity, signal compatibility, torque, and shaft adapter size. | Correct sizing is essential because insufficient torque can cause incomplete travel or repeated stall conditions. | Check for stalled movement, overheating, loose adapters, and incomplete damper closure or opening. | The damper load is modest and panel capacity is limited. |
