Johnson Controls VMA18 Series, MS-VMA1832 series, MS-VMA1826 series, VMA1826, VMA1832 Installation Instructions Manual

VMA1826/1832 VAV Controller Installation Instructions

MS-VMA1826-x, MS-VMA1832-x

Part No. 24-10143-373, Rev. J

Issued September 2018

Refer to the QuickLIT website for the most up-to-date version of this document.

Applications

The VMA18 Series programmable VAV box controllers
are intended for use as functional replacements for the
VMA1410, VMA1415, VMA1420, and the VMA1440
controllers.

VMA1826 controllers are well-suited for commercial
zoning applications and can be used for pressure
dependent VAV box applications where no differential
pressure tranduser (DPT) is required.

Note: With CCT Release 10.1 and higher, VMA18 Series

controllers can be configured as either N2 devices

or as BACnet® MS/TP devices. This ability

provides a potential cost-effective protocol
upgrade path for existing customers and should
be considered when you install the controller.

Important: When you receive a VMA18 Series

controller from the factory or upgrade the
firmware or main code, the controller
defaults to using the MS/TP
communications protocol. The Load
Summary screen of CCT 10.1 and above
shows the connection as Wired Field Bus,
indicating that the MS/TP protocol is in use.
If you have an N2 application, the Load
Summary screen indicates that you need
to switch the communications protocol to
N2.

North American Emissions
Compliance

United States

This equipment has been tested and found to comply
with the limits for a Class A digital device pursuant to
Part 15 of the FCC Rules. These limits are designed to
provide reasonable protection against harmful
interference when this equipment is operated in a
commercial environment. This equipment generates,
uses, and can radiate radio frequency energy and, if not
installed and used in accordance with the instruction
manual, may cause harmful interference to radio
communications. Operation of this equipment in a
residential area may cause harmful interference, in which
case the users will be required to correct the interference
at their own expense.

Canada

This Class (A) digital apparatus meets all the
requirements of the Canadian Interference-Causing
Equipment Regulations.
Cet appareil numérique de la Classe (A) respecte toutes
les exigences du Règlement sur le matériel brouilleur
du Canada.

These VMA controllers feature an integral digital pressure
sensor (VMA1832 model only), a damper actuator, and
a 32-bit microprocessor. The controller's small package
size facilitates quick field installation and efficient use of
space for field replacements, while still enabling precision
control performance.

Note: Connecting an IOM to the VMA via the SA Bus

connection is not supported.

For information about sensor compatibility and
replacement, see Sensor Replacement and Reuse

Scenarios.

Installation

Observe these guidelines when installing a VMA18 Series
controller:

• Transport the VMA controller in the original container
to minimize vibration and shock damage to the VMA
controller.

• Do not drop the VMA controller or subject it to physical
shock.

Parts Included

• One VMA18 Series controller with removable N2/FC
bus terminal block

• One installation instructions sheet

1VMA1826/1832 VAV Controller Installation Instructions

• Two 1/4 in. x 1/4 in. (6.35 mm x 6.35 mm) brass
fittings

• One self-drilling No. 10 x 25 mm (1 in.) screw

• Two 12-in. (30.48 cm.) pieces of flexible tubing

• One controller/sensor Y cable adapter

• One 8-pin to 6-pin single-socket cable adapter

Note: Remove the cap plug from the TSTAT port of the

controller and save for future use. The cap plug
is used on existing sensor ports that are no longer
used.

Materials and Special Tools Needed

Note: You may not require all the materials listed for

your controller installation.

• Several 6 mm (1/4 in.) female spade terminals for
input and output wiring and crimping tool or spade
mounted terminal blocks

• Small straight-blade screwdriver for securing wires in
the terminal blocks

• 8 mm (5/16 in.) wrench or 10 mm (3/8 in.) 12-point
socket to tighten the square coupler bolt

• Several shims or washers to mount the VMA

• Power screwdriver, 100 mm (4 in.) extension socket,
punch, drill, and 3.5 mm (9/64 in.) drill bits to mount
the VMA

• Pliers to open and close the damper

• Required length of 3.97 mm (5/32 in.) ID pneumatic
tubing and barbed fittings

Mounting

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.

• Mount the VMA in an area free of corrosive vapors
that matches the ambient conditions specified in the

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
VMA1410, VMA1415, VMA1420, and the VMA1440
controllers, we recommend plugging the unused open
hole with the screw from the original VMA14 mounting
when using the VMA18 to replace a VMA14 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 VMA18 Series controller, complete the
following steps:

1. Place the VMA18 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
requirements (Figure 1).

Figure 1: Possible VMA18 Series Controller

Mounting Positions

• 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.

Make sure the VMA controller base is parallel to the
VAV box (perpendicular to the damper shaft). If

2VMA1826/1832 VAV Controller Installation Instructions

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 VMA18
controller movement in either direction.

2. Secure the self-drilling No. 10 screw through the

shoulder washer (Figure 3) 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 VMA1410, VMA1415, VMA1420, and the
VMA1440 controller. We recommend
plugging the unused open hole with the screw
from the original VMA14 mounting when
using the VMA18 to replace a VMA14 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 (Figure 2).

Figure 2: Typical Damper End Shaft Icons

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.

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 3). 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.

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 3) 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.

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.

3VMA1826/1832 VAV Controller Installation Instructions

Figure 3: VMA18 Series Controller Wiring Terminations and Physical Features

4VMA1826/1832 VAV Controller Installation Instructions

Table 1: VMA18 Series Controller Feature Callout Numbers and Descriptions

Physical Features: Description and ReferencesCallout

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

24 VAC, Class 2 Supply Power Spade Terminals (see Supply Power Spade Terminals)

Device Address DIP Switch Block (see Setting the Device Address)

Binary Outputs, 24 VAC Triacs (see Table 4)

Configurable Outputs: Voltage Analog Output (0–10 VDC) and Binary Output (24 VAC Triac) (see

Table 4)

Dual Port Fitting (see Figure 3)

Not included in the VMA1826 model.

Manual Override Switch (see Mounting)

Controller Coupler (see Mounting)

Coupler Bolt (see Mounting)

Universal Input: Voltage Analog Input (0–10 VDC)

Resistive Analog Inputs (0–600k ohm) (see Table 4):

0–2k Potentiometer

RTD: 1k Nickel, 1k Platinum, or A99B SI

NTC: 10K Type L (10K JCI Type II is equivalent to Type L) or 2.252K Type II

Dry Contact Binary Input

N2/FC Bus Pluggable Screw Terminal Block (see N2/FC Bus Terminal Block)

EOL (End-of-Line) Switch (see Setting the EOL Switch)

SA Bus Spade Terminals (see SA Bus Spade Lugs)

TSTAT Modular Port: RJ-45 8-Pin Modular Jack (see Modular Port)

Captive Spacer and Screw (see Figure 3)

LED Status Indicators (see Table 8)

Wiring

Risk of Electric Shock. Disconnect the power supply

before making electrical connections to avoid electric
shock.

Mise En Garde: Risque de décharge électrique:

Débrancher l'alimentation avant de réaliser tout
raccordement électrique afin d'éviter tout risque de
décharge électrique.

Important: Do not connect supply power to the

controller before finishing wiring and
checking all wiring connections. Short
circuits or improperly connected wires can
result in damage to the controller and void
any warranty.

Important: Do not exceed the controller electrical

ratings. Exceeding controller electrical
ratings can result in permanent damage to
the controller and void any warranty.

Important: Use copper conductors only. Make all wiring

in accordance with local, national, and
regional regulations.

Important: Electrostatic discharge can damage

controller components. Use proper
electrostatic discharge precautions during
installation, setup, and servicing to avoid
damaging the controller.

For detailed information on configuring and wiring an N2
Bus, refer to the N2 Communications Bus Technical
Bulletin (LIT-636018).

VMA Terminals and Bus Ports

See Figure 3 for input and output terminal and bus port
locations on the VMA18 Series controllers. Observe the
following guidelines when wiring a VMA18 controller.

5VMA1826/1832 VAV Controller Installation Instructions

Input and Output Terminals

The input spade terminals are located on the bottom of
the VMA near the N2/FC Bus terminal block. The output
spade terminals are located on the top of the controller
near the power supply spade terminals. See Table 4 for
more information.

N2/FC Bus Terminal Block

The N2/FC Bus terminal block is a blue, removable,
4-terminal plug that fits into a board-mounted jack.

Wire the removable N2/FC Bus terminal block plugs on
the VMA and other field controllers in a daisy-chain
configuration using 3-wire twisted, shielded cable as
shown in Figure 4. See Table 5 and Table 6 for more
information.

Figure 4: N2/FC Bus Terminal Block Wiring

Figure 5: SA Bus Spade Lug Wiring

Note: Connecting an IOM to the VMA by using the SA

Bus connection is not supported.

Modular Port

The modular (TSTAT) port on the face of the VMA

(Figure 3) is an RJ-45, 8-position modular jack used to
connect your new or existing sensor to the VMA using
one of the two included adapters. Refer to the Sensor
Replacement section in the N2 VMA Application Note
(LIT-12011829).

Note: The Shield terminal (SHLD) on the N2/FC Bus

terminal block is isolated and can be used to
connect the cable shields on the bus (Figure 4).

SA Bus Spade Lugs

Wire the SA Bus spade lugs on the VMA and other SA
Bus devices in a daisy-chain configuration using 4-wire
twisted, shielded cable as shown in Figure 5. See Table

6 for more information.

Figure 6: Pin Number Assignments for the Modular

Port on VMA18 Controllers

6VMA1826/1832 VAV Controller Installation Instructions

Supply Power Spade Terminals

Wire the 24 VAC supply power wires from the transformer
to the HOT and COM terminals on the spade terminal as
shown in Figure 7. See Table 6 for more information.

Figure 7: 24 VAC Supply Power Spade Terminal

Wiring

Important: The supply power terminal block on the

VMA18 is a two-position spade lug (Figure

7). Exercise caution while rewiring the

power plug when replacing an existing
controller. Stray wire strands may make
contact and cause a short circuit across the
24 VAC power supply.
To maintain proper phasing when replacing
the existing VMA14xx controller with the
VMA18 controller, connect the power wire
from 24 VAC: 1 terminal on the existing
controller to the HOT power terminal on the
VMA18. Also connect the power wire from
the 24 VAC: 2 terminal on the existing
controller to the COM power terminal on the
VMA18 controller.

Figure 8: Transformer Grounding

Improper wiring of this terminal may cause a short circuit
across the 24 VAC power supply on -1 models.

To wire the VMA18 Series controller, complete the
following steps:

1. Terminate wiring per engineering drawings.

2. Wire network sensors and other devices to the VMA's

Sensor/Actuator (SA) Bus.

3. Wire the N2/FC Bus in a daisy chain (see Table 6).

4. Ensure that the VMA’s device address DIP switches

are set to the appropriate device address. (See

Setting the Device Address.)

5. Connect the VMA controller to 24 VAC, Class 2

power.

Refer to the N2 VMA Application Note (LIT-12011829)
for more information about replacing an existing controller
with an VMA18 controller.

VMA Terminal Functions, Ratings,
Requirements, and Wiring Guidelines

The supply power wire colors may be different on
transformers from other manufacturers. Refer to the
transformer manufacturer’s instructions and the project
installation drawings for wiring details.

Important: Connect 24 VAC supply power to the VMA

and all other network devices so that
transformer phasing is uniform across the
network devices. Powering network devices
with uniform 24 VAC supply power phasing
reduces noise, interference, and ground
loop problems. The VMA does not require
an earth ground connection. However, when
grounding the secondary of the 24 VAC
transformer is required, only one connection
to ground should be made near the
transformer.

Input and Output Wiring Guidelines

Table 4 provides information about the functions, ratings,

and requirements for the VMA input and output terminals,
and Table 5 provides guidelines for wire sizes and cable
lengths.

In addition to the wiring guidelines in Table 4, observe
these guidelines when wiring VMA inputs and outputs:

• Run all low-voltage wiring and cables separate from

high-voltage wiring.

• All input and output cables, regardless of wire size or

number of wires, should consist of twisted, insulated,
and stranded copper wires.

• Shielded cable is not required for input or output

cables.

7VMA1826/1832 VAV Controller Installation Instructions

• Shielded is recommended for input and output cables
that are exposed to high electromagnetic or radio
frequency noise.

• Cable runs of less than 30 m (100 ft) typically do not
require an offset in the input/output software setup.
Cable runs over 30 m (100 ft) may require an offset
in the input/output software setup.

Maximum Cable Length versus Load Current

Use Figure 13 to estimate the maximum cable length
relative to the wire size and the load current (in mA) when
wiring inputs and outputs.

N2/FC and SA Bus and Supply Power Wiring
Guidelines

Table 6 provides information about terminal block

functions, ratings, and requirements.

Table 6 also provides wire size, cable type, and cable

length guidelines for wiring the VMA communication
buses and supply power.

In addition to the guidelines in Table 6, observe these
guidelines when wiring the SA and N2/FC Buses and
supply power:

• Run all low-voltage wiring and cables separate from
high-voltage wiring.

• All N2/FC and SA Bus cables, regardless of wire size,
should be twisted, insulated, stranded copper wire.

• Shielded cable is strongly recommended for all N2/FC
and SA Bus cables.

•

Refer to the N2 Communications Bus Technical
Bulletin (LIT-636018) for detailed information
regarding wire size and cable length requirements for
the N2/FC and SA buses.

Termination Diagrams

A set of Johnson Controls® termination diagrams provides details for wiring inputs and outputs to the VMA18 Series

controllers. See the figures in this section for the applicable termination diagrams.

Table 2: Termination Details

Type of Field
Device

External Source

Input/Output

UIVoltage Input -

Termination DiagramsType of

UIVoltage Input -

Internal Source

UIVoltage Input

(Self-Powered)

8VMA1826/1832 VAV Controller Installation Instructions