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#4 Adjust for mountings or accessories
The final two options that are available for the damper
actuators are dual-auxiliary switches and specific mounting
connections.
Auxiliary switches help verify the actuator positioning, since
a contact can be used to operate other low voltage devices at
5% and 85% of the actuator’s rotation.
If there are any difficulties in mounting the actuator to the
shaft, Siemens has a variety of mounting accessories such as
foot mounts, tandem mounts, linkage kits and even rotary to
linear kits that can be used for OpenAir actuators.
For installations requiring a bit more protection from the
elements, consider adding a weather shield.
Now that all the steps have been covered to select the right
actuator, let's review the original example. The outside air
damper required 95-inch pounds of torque to properly open.
Since it is an outside air application, a fail-safe spring return
actuator is required. 24Vac is common in this application,
along with a modulating 2-10V signal, with dual auxiliary
switches built in to ensure the fan starts and stops depending
on the actuator’s rotation. In this scenario, the damper shaft
is easily accessible, and no specific accessories are needed.
Taking all that information and looking through the Siemens
brochure, online HIT tool, or catalog, it is decided that a
Siemens GCA156.1P actuator is the perfect fit.
Actuator Selection Checklist

Assess damper physical properties
 Check the specifications
 Understand application requirements
 Adjust for mounting or accessories
Outside Air Damper Example Recap:
• Torque Requirement = 94.5 Lb.-In
• Fail-Safe is needed = Spring Return
• Voltage = 24Vac
• Control Signal = Modulating 2-10V
• Aux. Switches = Yes
• No specific accessories needed
In the end, following these steps in this checklist will save you time,
money and headaches in the future.
GCA156.1P
Actuator Selection Checklist
1. Assess damper physical properties
2. Check the specifications
3. Understand application requirements
4. Adjust for mounting or accessories

Putting it all together