Which type of actuator is best? It depends on what you need it for.
What are they?
First, let's answer the question: what are actuators?
Actuators control the movement of adjustable blades on dampers and adjustable louvers. Actuators can be manually operated or automatically controlled, for two-position or modular action.
In other words, an automated actuator can move blades to one of two positions - usually fully open and fully closed - or adjust the position to any angle you want. Automated actuators can also help create a fully automated HVAC system.
A manual actuator is a cost-effective option, but it will require regular access to the damper and needs an operator to control the actuator.
Manual actuators are often referred to as hand quadrants, because you must adjust the actuator by hand. Hand quadrants are levers installed on the linkage, which operators use to adjust the blades.
These actuators are best suited for blades that only require occasional adjustments. Hand quadrants are the cheapest option, but they require access to the louver or damper being adjusted.
You may not be able to freely adjust the hand quadrant. Adjustable louvers are generally installed in or near a building's walls, making them difficult to access. In these situations, a manual actuator may not be your best option.
With automatic actuators, you don't need access the louver or damper.
Automatic actuators control blade movement through pneumatic action or with an electric motor. These are known as pneumatic actuators and electric actuators.
Pneumatic actuators use compressed air to move an enclosed piston up and down. This action is tied to the blades, adjusting them open or closed as the piston moves. These actuators can provide precise control for a relatively low cost per actuator.
However, pneumatic actuators require a compressor system to generate compressed air and air lines to feed it into the actuators. Pneumatic actuators are cheap because of their simple design, but the compressor and air line systems are expensive to install. Older buildings may already have these systems installed. In that case, pneumatic actuators are the best option.
Most modern projects use electric actuators for their adjustable louvers and dampers.
Electric actuators use small electric motors to control the adjustable blades, allowing for even greater precision than pneumatic actuators. Also, advances in technology have made electric actuators a cheaper and more effective option for automating adjustable louvers and dampers.
These actuators can be easily connected to digital controllers for a fully autonomous HVAC solution. From the controller, actuators can be individually configured. This controller can adjust the blade positions of multiple dampers and louvers at once.
Although electric actuators have a set-and-forget functionality, all actuators require regular inspection and maintenance to ensure their parts are in good condition.
Options for Actuators
Actuators can be customized for a specific situation. Adjustable louvers and dampers can also receive additional accessories to assist the actuator's actions. Below are a few of the options:
"Power Open - Spring Close": This option will open the damper/louver when power is applied to the actuator. Springs inside the actuator will force the damper/louver to close when power is removed. This is the standard action for most actuators and is required for UL Life Safety dampers.
"Power Close - Spring Open": The opposite of "Power Open - Spring Close". The actuator will close the damper/louver when power is applied and the internal springs will open the damper when power is lost.
Jumper Bracket: A device that assists the movement of dampers and louvers connected together in a single unit. The jumper bracket connects to the blade of each section, bridging the louver/damper panels together and synchronizing their blade movement. This can assist the connect actuator by reducing the amount of torque required to open and close the blades.
Dual Position Indication (DPI) Switch: A device installed on actuators to show which position the blades are in at a given time. Some models of DPI switches can be customized to indicate different blade angles.
Most actuators have an integral DPI switch already installed, but you can also choose to have a separate DPI switch installed in the damper. External DPI switches can monitor blade position and shaft rotation, as opposed to the integral DPI switch that only monitors blade position. External DPI switches can be important in diagnosing a mechanical failure in the damper.
It seems like electric actuators are the way to go: cheap to build, easy to setup, and highly automated.
However, there may be instances where a pnuematic actuator or a hand quadrant would work better for your needs.
The main cost comes from installing and maintaining the air compression systems. If you already have the air lines and compressor system in place, then pneumatic actuators are a no-brainer. Despite the advances in electric motors, pneumatic actuators still have a lower per-unit cost than electric actuators.
The cheapest option of all is the manual hand quadrant actuator. If you have easy access to the damper or louver, and you don't need to adjust it often, then you may consider using a hand quadrant to adjust the blades.
Saving money is always a good thing, especially if you're building an HVAC system from the ground up. But a fully automated HVAC system, using electric actuators, may save you time and money in the long run. It all depends on what works best for your project.
MCDLG & Continuing Education
This course provides continuing education credits for a variety of institutions, including AIA's LIUs. Learn the basics of louvers and earn credit, at your own pace. Visit the MCDLG course page on AECDaily.com today!