Mounting
Observe the following guidelines when mounting a
VMA:
Note:
When the air supply to the VAV box
is below 10°C (50°F), make sure that any
condensation on the VAV box, particularly on
the damper shaft, does not enter the VMA
• Ensure that the mounting surface can support
the controller and any user-supplied enclosure.
electronics. Mount the controller vertically above
the damper shaft to allow any shaft condensation
to fall away from the controller. Additional
measures may be required in some installations.
• Mount the controller on a hard, even surface
whenever possible.
• Use shims or washers to mount the controller
securely and evenly on the mounting surface.
• Mount the controller in an area free of corrosive
vapors that matches the ambient conditions
• Provide sufficient space around the controller
for cable and wire connections and adequate
ventilation through the controller (at least 50 mm
[2 in.] on the top, bottom, sides, and front of the
controllers).
• Mount the VMA vertically above the damper shaft
to allow any shaft condensation to fall away from
the VMA.
Do not mount the controller in areas where
electromagnetic emissions from other
devices or wiring can interfere with controller
communication.
• Avoid mounting the controller on surfaces with
excessive vibration.
On panel or enclosure mount applications, observe
these additional guidelines:
• Do not install the controller in an airtight
enclosure.
• Mount the controller so that the enclosure walls
do not obstruct cover removal or ventilation
through the controller.
• Mount the controller so that the power
transformer and other devices do not radiate
excessive heat to the controller.
To mount the controllers, complete the following
steps:
1. Set all the switches on the field controller to
their known settings.
2. Place the controller in the proper mounting
position on the damper shaft so that the wiring
connections are easily accessible. Make sure
the controller base is parallel to the VAV box
(perpendicular to the damper shaft). If needed,
use a spacer to offset tipping of the controller
caused by the shaft bushings.
Note:
Use the alignment marks to center
the captive spacer to ensure sufficient
movement in either direction.
3. Secure the self-drilling No. 10 screw through
the captive spacer with a power screwdriver
and 100 mm (4 in.) extension socket. Otherwise,
use a punch to mark the position of the
shoulder washer, and then drill a hole into the
VAV box using a 3.5 mm (9/64 in.) drill bit. Insert
the mounting screw and tighten against the
spacer.
Important:
Do not overtighten the screw,
or the threads may strip. If mounting to
the VAV box, make sure the screws do not
interfere with damper blade movement.
4. Locate the damper position using the typical
marking on the end of the damper shaft as
shown in the following figure.
Figure 2: Typical Damper End Shaft Icons
5. Note the direction, clockwise (CW) or
counterclockwise (CCW), required to close the
damper. Grasp the damper shaft firmly with
pliers, and either manually close the damper for
90° boxes or manually open the damper for 45°
or 60° boxes.
VMA1930 VAV Controller Installation Guide
4