Part of a heating, ventilation, and air conditioning (HVAC) system, a damper actuator controls the opening and closing of a damper. Opening the damper allows air from outside a building to enter, in order to cool the interior, or it can close to contain the inside air. Damper actuators are available from manufacturers in both electrical and pneumatic configurations. Spring return, rotary, and linear variations are made as well. Which kind of damper actuator used depends on the type and configuration of the HVAC system in the building.
The purpose of a damper actuator is to allow an HVAC system to bring in outside air, or move the damping system in such a way that air cannot get in. An air conditioning system may not have to be run at the power needed to cool every space in a building. If the outside temperature is suitable, then making use of outside air is cost-effective and less straining on the overall mechanical system. Air that is further cooled in the system will enter the building, and the actuator can also push warm air out as the air within cools.
In systems that are controlled by air pressure, pneumatic damper actuators are used. These typically have a spring that moves the actuator, which is activated by changes in air pressure within the control system. Electric actuators, in contrast, are controlled by motors. Other types of actuators for HVAC dampers include spring-return, as well as non spring-return actuators which are generally driven by motors.
A solenoid is sometimes included in a damper actuator. This helps to open and close the damper part by converting the available energy into the motion needed to do the task. Commercial HVAC systems usually implement stainless steel solenoids that can tolerate corrosive environments. The actuators can also be mounted in various ways, often with the use of separately purchased kits. Manufacturers also customize damper actuators for customers based on characteristics such as airflow volume.
Any damper actuator operates in conjunction with other air conditioning parts. The type of damper seals, how many damper sections there are, and the velocity of the air therefore have to be considered before one is installed. Factors also include the static pressure of the system under normal conditions. These variables can be calculated by finding out what the damper torque and damper area are. Mathematical formulas help to decide the size and type of actuator that is most suitable.