Key Concepts; Vma Position And Orientation; Damper Actuator Direction To Close; N2 Address Switches - Johnson Controls VMA1400 Series Manual

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Mounting and Wiring VMA1400 Series Controllers Technical Bulletin

Key Concepts

VMA Position and Orientation

Damper Actuator Direction to Close

N2 Address Switches

Consider the following when positioning and orienting the VMA:
• Mount the VMA on a vertical and flat surface where it functions
best, such as the side of the VAV box.
• Route the tubing so a portion of it is lower than the pressure
sensor, or loop the tubing. This creates a moisture trap that
prevents any condensation from entering the sensor.
• Do not make any sharp bends in the tubing. This could collapse the
tube and block the pressure path.
• Verify wiring terminals are accessible.
• Ensure that no extra mounting brackets, linkage, or couplers are
required for standard mounting.
• Locate the VMA so that it has adequate clearance for future
servicing and is protected from moisture and corrosive fumes.
The damper actuator direction to close is established upon installation
of the VMA, using HVAC PRO software. The damper must be
manually positioned to allow the VMA actuator to fully open and
close the damper. Incorrect damper positions in a zone can lead to
misdiagnosed readings, resulting in unnecessary repetition of setup
and diagnostics.
It is best, from an accessibility standpoint, to set the N2 switches
before mounting the VMA. The switches, located on the side of the
VMA, are set to On for the address numbers indicated on the room
schedule or building drawings. Use Addresses 1-253 only.
Addresses 0, 254, and 255 are reserved. Refer to the Preparing the
VMA for Mounting section in this document for further information.
If software addressing is used, N2 switches must be set to 0 or 255.
See the HVAC PRO User's Guide for details on software addressing.