Dampers serve many different purposes in your HVAC system, but their most common role is directing airflow. Control dampers open and close their blades to direct air through the ducts. This simple action can deliver conditioned air to rooms that need cooling, or direct stale air to exhaust points in your system. Wherever they are, and whatever they do, control dampers need the means to act on their own. This is where damper motors come in.

A damper in the full open position — Control dampers need to open and close on a regular basis. There are a few ways to achieve this.

What is a motorized damper?

Motorized dampers are dampers equipped with a specialized motor that controls the damper’s blade rotation. The motor is attached to the damper’s driving blade, which is tied to the other blades via the linkage. When activated, the motor will rotate the driving blade. The linkage will translate the rotation to all attached blades.

The damper’s motor is called the actuator. In HVAC, we often use motor and actuator interchangeably, but we use the term actuator more often to broaden the scope to other types of devices.

Actuators – The Motor of Your Damper

Actuators are the motor that opens and closes your damper. They achieve this by rotating the damper's blades. Modulating actuators will hold blade angles between fully open and fully closed. We will cover how to utilize modulating actuators later in this article.

There are three primary types of actuators: manual actuators, pneumatic actuators, and electric actuators. Here is a breakdown of each type.

The three common types of actuators — There are three common types of actuators: manual actuators, pneumatic actuators, and electric actuators.

Manual Actuators: Hand powered actuators that require a person to operate. This includes actuators like hand quadrants, hand cranks, chain wheel actuators, and snake gear actuators. An operator must be present to use these devices. For example, an operator would pull the quadrant’s lever down to open the damper. The actuator must be easy to access, so that operators can readily open and close the damper.

Pneumatic Actuators: Actuators that use air pressure to function. Pneumatic actuators have an internal chamber that holds a diaphragm and a piston. The piston is attached to the damper’s driving blade with a clevis. Air tubes fill the diaphragm with air when the actuator is activated, which drives the piston down. The damper’s blades will rotate with the piston. The clevis translates the piston's up-and-down action into a rotation. This action can open or close the damper, depending on how the piston is connected to the blade axle. Once finished, the actuator will release the air from the diaphragm and the piston will return to its neutral position. The blades will also return to their neutral position, either fully open or fully closed.

Electric Actuators: Actuators that employ an electric motor to rotate the damper’s blades. They will have an internal rotary coupling that slides over the extended shaft of the damper’s driving blade. Once secured, this rotary coupling will rotate the damper’s blades when it receives power. When powered off, the actuator will return to its neutral position with help from an internal spring mechanism. The opening and closing action will depend on how the actuator is configured:

A “power open, spring closed” actuator will open when the actuator has power and close when powered off.
A “spring open, power closed” actuator will close when power is applied, and open when power is removed.
Most electric actuators will be power open, spring closed, so that the damper closes when the actuator has no power.

Electric actuators can also be designed to “modulate” or hold blade angles between fully open and fully closed. Modulating actuators can receive multiple electrical signals to hold a specific blade angle, depending on the needs of the system. This can be useful for applications that require precise air pressure control.

Damper with an electric actuator — Actuators are attached to the damper's driving blade axle, so that it controls the rotation of the damper's blades.

HVAC Damper Automation

Pneumatic and electric actuators allow you to automate your control dampers, so that they open and close at the right times throughout your system. Pneumatic actuators can be timed to open and close when air should pass through a particular part of the HVAC system. This is good for systems that run on a strict schedule, and buildings with a central air compressor already installed.

Electric actuators provide the most control. These actuators can be tied to a central control system, which can monitor the system and direct air to where it’s needed by sending signals to the actuators. All electric actuators tied to the system can operate individually, based on the computer’s signals. This way, control dampers will open and close as the central system needs them.

Electric actuators can help complete a smart HVAC system. A smart system provides the most comfortable environment using the least amount of power, which can help reduce the building’s overall carbon footprint. In other words, motorized dampers can help make your project eco-friendly. Always consider your options when adding actuators to your dampers.

Three examples of actuators — Each actuator type has its advantages and disadvantages. The key to choosing the right one is understanding the needs of your specific application.

Necessary Maintenance

Every actuator needs regular maintenance. Technicians should test actuators to ensure they can properly rotate the damper’s blades.

Consult the manufacturer’s instructions for complete guidelines on proper maintenance.
Check for signs of binding or slippage and adjust the actuator as needed. Blades should rotate smoothly with the actuator action.
Replace non-working actuators with new ones.
Keep actuators clean. Use a lint-free cloth to remove loose dust or grime.

Motorized Dampers from AWV

Motorized dampers keep air moving to the right place in your system. You need control dampers that open and close on time. A missed opening will cost you system efficiency.

Trust American Warming and Ventilating (AWV). We offer a wide range of products designed to meet your specific requirements. AWV is the go-to source for quality motorized dampers with industry-leading actuators. Contact us today to learn how our products can enhance the performance and efficiency of your HVAC system!

Motorized Dampers for HVAC