Mounting - Metasys - MS-VMA1826-x - MS-VMA1832-x - Field Device - VMA18 VAV Modular Assembly

VMA1826/1832 VAV Controller Installation Guide

Product name
VMA18 VAV Modular Assembly
Document type
Installation Guide
Part number
Document revision
Revision date

Observe these guidelines when mounting a VMA :

Important: 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 electronics. Mount the VMA vertically above the damper shaft to allow any shaft condensation to fall away from the VMA . Additional measures may be required in some installations.
  • Ensure the mounting surface can support the VMA and any user-supplied enclosure.

  • Mount the VMA on a hard, even surface whenever possible.

  • Use shims or washers to mount the VMA securely and evenly on the mounting surface.

  • Mount the VMA in an area free of corrosive vapors that matches the ambient conditions specified in the VMA1832 Technical Specifications section.

  • Provide sufficient space around the VMA for cable and wire connections and adequate ventilation through the controller (50 mm [2 in.] minimum on the top, bottom, sides, and front of the controllers).

  • Do not mount the VMA in areas where electromagnetic emissions from other devices or wiring can interfere with controller communication.

  • Avoid mounting the VMA on surfaces with excessive vibration.
  • Because the VMA controller is smaller than the VMA 1410, VMA 1415, VMA 1420, and the VMA 1440 controllers, we recommend plugging the unused open hole with the screw from the original VMA 14 mounting when using the VMA18 to replace a VMA 14 Series controller.

On panel or enclosure mount applications, observe these additional guidelines:

  • Do not install the VMA in an airtight enclosure.
  • Mount the VMA so that the enclosure walls do not obstruct cover removal or ventilation through the controller.

  • Mount the VMA so that the power transformer and other devices do not radiate excessive heat to the controller.

To mount the VMA 18 Series controller, complete the following steps:

  1. Place the VMA 18 Series controller in the proper mounting position on the damper shaft so that the wiring connections are easily accessible.
    Note: The line from the captive spacer and screw through the center of the damper shaft must be either horizontal or vertical, and the wall plate must be wall-mounted to comply with UL requirements. See the following figure for possible mounting positions.
    Figure 1. Possible VMA18 Series Controller Mounting Positions

    Make sure the VMA controller base is parallel to the VAV box (perpendicular to the damper shaft). If needed, use a spacer to offset tipping of the VMA controller caused by the shaft bushings.
    Note: Using the alignment marks to center the captive spacer ensures sufficient VMA 18 controller movement in either direction.
  2. Secure the self-drilling No. 10 screw through the shoulder washer ( Figure 1 ) 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 washer.
    Note: The mounting screw for the VMA controller does not use the same hole as the screw for the VMA 1410, VMA 1415, VMA 1420, and the VMA 1440 controller. We recommend plugging the unused open hole with the screw from the original VMA 14 mounting when using the VMA18 to replace a VMA 14 Series controller.
    Important: Do not overtighten the screws, or the threads may strip. If mounting to the VAV box, make sure the screws do not interfere with damper blade movement.
  3. Locate the damper position using the typical marking on the end of the damper shaft. See the following figure.
    Figure 2. Typical damper end shaft icons

  4. 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).
  5. Push down and hold the Manual Override button ( Figure 1 ) and turn the VMA controller coupler until it contacts the mechanical end-stop at either the fully closed (90° boxes) or fully open (45° and 60° boxes) position.
  6. If the damper for a 90° box closes CCW, rotate the coupler to the CCW mechanical limit. If the damper for a 90° box closes CW, rotate the coupler to the CW mechanical limit. The open end-stop is automatically set for 90° boxes. For 45° and 60° boxes, hard stops must be provided at both fully closed and fully open damper positions. By installing the VMA controller at the fully open position, the VMA controller provides the open stop for 45° and 60° boxes. The closed damper seal provides the fully closed stop.
    Important: The integrated actuator has a stroke time of 60 seconds for 90° of travel. The stroke time is the amount of time (in seconds) that it takes the actuator to move from the fully closed to fully opened position or from fully open to fully closed position. For proper operation, the actuator stroke time must be configured in the CCT application based on the actual time it takes the actuator to drive the damper. The default setting is 60 seconds (for 90° VAV boxes). For 45° and 60° VAV boxes, the actuator stroke time must be adjusted. Refer to the Controller Tool Help (LIT-12011147) for instructions on setting the actuator stroke time in the application.
  7. Tighten the square coupler bolt to the shaft using an 8 mm (5/16 in.) wrench or 10 mm (3/8 in.) 12-point socket. Tighten to 10.5 to 11.5 N·m (95 to 105 lb·in).
  8. Loop the pneumatic tubing to include a trap for condensation. If needed, use the included brass fittings and attach the included pieces of tubing to the tubing of the VMA controller. Attach the tubing from the VMA controller to the dual port fitting on the VMA controller and the other ends of the tubing to the pressure transducer in the VAV box application ( Figure 1 ). The VMA1826 does not come with the tubing pieces.
    Note: The VMA uses a digital non-flow pressure sensor with bidirectional flow operation, which allows the high- and low-pressure DP tube connections to be made to either barbed fitting on the VMA controller. You do not need to make a specific high- or low-side connection when you attach the tubing to the barbed fittings on the VMA .
  9. Push the manual release button, and turn the actuator coupling manually to ensure that the actuator can rotate from full-closed to full-open positions without binding.
  10. Complete the mounting by rotating the damper to the full-open position.
  • Risk of Property Damage
  • Rotate the damper to the full-open position before starting the air handler. Failure to rotate the damper to the full-open position may result in damage to the VAV box or ductwork when the air handler is started.
  • Mise En Garde: Risque de dégâts matériels
  • Faire pivoter le registre pour le placer en position d'ouverture complète avant de démarrer l'unité de traitement d'air. Le non-respect de cette directive risque d'endommager le caisson de l'unité à volume d'air variable (VAV) ou le réseau de conduites au démarrage de l'unité de traitement d'air.