Johnson Controls VMA 1410, VMA 1400 Series, VMA 1430, VMA 1420 Overview And Engineering Manuallines

Technical Bulletin

Issue Date February 28, 2006

Variable Air Volume Modular Assembly (VMA) 1400

Series Overview and Engineering Guidelines

VMA1400 Series Overview and Engineering Guidelines ...................2

Introduction......................................................................................................... 2

Key Concepts...................................................................................................... 3

VMA1400 Series Models...................................................................................................3

VAV System......................................................................................................................6

Definition of Terms............................................................................................................9

Room Sensor Placement ................................................................................................10

Pressure Independence..................................................................................................10

VMA Airflow Rate............................................................................................................10

Power Source..................................................................................................................11

N2 Bus Rules..................................................................................................................12

Inputs and Outputs..........................................................................................................13

Zone Bus.........................................................................................................................14

CablePRO.......................................................................................................................15

CVTPRO.........................................................................................................................15

Related Documentation...................................................................................................16

Application Examples......................................................................................................17

Reference Information.....................................................................................................26

Specifications..................................................................................................................27

Detailed Procedures.........................................................................................32

Determining VAV Box Requirements..............................................................................32

Establishing the Room Schedule....................................................................................32

Developing the Bill of Material and Placing Orders.........................................................33

Configuring the VMA.......................................................................................................35

© 2006 Johnson Controls, Inc. www.johnsoncontrols.com
Code No. LIT-6363120

VMA1400 Series Overview and Engineering Guidelines Technical Bulletin 2

VMA1400 Series Overview and
Engineering Guidelines

Introduction

The Variable Air Volume Modular Assembly (VMA) 1400 Series is a
configurable, integrated module that includes a Variable Air Volume
(VAV) controller, differential pressure sensor, and, with the exception
of the VMA1430, an actuator.

Note: This document focuses on the VMA1410, 1420, and 1430
controllers. The VMA1400 Series also includes the VMA1440, which
is used exclusively as part of the Metasys® Zoning Package. See the

Metasys Zoning Package Product Bulletin (LIT-639050) and the
Metasys Zoning Package Overview Technical Bulletin (LIT-639100)

for information on this specialized product.
The VMA engineering procedures vary from location to location. The

information provided here is a general engineering guideline. Where
available, use the Advanced Installation Management (AIM) tools for
developing schedules and drawings.

This document provides a VMA1400 Series overview and describes
how to:

determine VAV box requirements
establish the room schedule
develop bills of material and place orders
configure the VMA

VMA1400 Series Overview and Engineering Guidelines Technical Bulletin 3

Key Concepts

VMA1400 Series Models

VMA1410
VMA1420

Figure 1: VMA1400 Series Models

VMA1430

VMA14xx

The VMA is a configurable, integrated module that includes a VAV
controller and differential pressure sensor. The VMA1400 Series
includes three models:

VMA1410 (cooling only, includes actuator)
VMA1420 (cooling with reheat, includes actuator)
VMA1430 (controller and differential pressure sensor only for use

with an external incremental or proportional actuator)

Note: The VMA1400 Series also includes the VMA1440, which is
used exclusively as part of the Metasys Zoning Package. See the

Metasys Zoning Package Product Bulletin (LIT-639050) and the
Metasys Zoning Package Overview Technical Bulletin (LIT-639100)

for information on this specialized product.
The models are designed for pressure independent, single duct

(all VMA1400 Series models), and dual duct (VMA1420 and
1430 only) applications. The VMA1420 and 1430 models can be used
with parallel or series fan-powered boxes.

Note: The VMA1420 can be configured for the Metasys Zoning
Package application, but the internal pressure sensor can only be used
for monitoring purposes. Refer to the Metasys Zoning Package
Commissioning Technical Bulletin (LIT-639250).

VMA1400 Series Overview and Engineering Guidelines Technical Bulletin 4

Table 1: VMA1400 Series Comparison Checklist

VMA Features 1410 1420 1430 Comments

Applications
Pattern Recognition Adaptive

Control (PRAC) on Zone Proportional
plus Integral plus Derivative (PID)
Temperature Loops

Adaptive Flow Control Loops

Single Duct, Pressure Independent

VAV

Side Loops without Interlocking

Single Duct Supply/Exhaust VAV
Fan Powered Boxes

Incremental, Proportional

Two Position, and Three Stages of
Box Heat

Incremental, Proportional

Two Position, or One Stage
Supplemental Heat

Dual Duct, Pressure Independent

VAV
Damper Actuator (Internal)
Accurate Positioning
Stall Detection
Automatic Damper End Stop

Detection at Power Up
Clockwise (CW)/

Counterclockwise (CCW)

Rotation Selection
EP8000 with Pneumatic Actuator
Software Tools
Ability To Download Code Firmware

Diagnostics
Moving Average Flow/Temperature

Diagnostic

Actuator Stall
Flow Test
Data Graphing

Starved Box Detection

Actuator Duty Cycle Diagnostic
Continued on next page . . .

Y Y Y Eliminates manual tuning and

seasonal re-tuning

Y Y Y Eliminates manual tuning,

improves control and energy
savings

Y Y Y Meets most VAV applications

N Y Y Single Analog Input (AI) to Analog

Output (AO) or Binary Output
(BO)

N Y Y Flow differential control
N Y Y Series or parallel

N Y Y Staged heat or normally

open/normally closed valves

N Y Y Normally open or closed valves

N Y Y Flexible flow setpoint specification

Y Y N/A 23,000 step resolution
Y Y N/A Detects damper travel stops
Y Y N Sets damper stroke time

Y Y Y Set via HVAC PRO™ software for

either direction to close

N Y Y

Y Y Y Allows firmware code upgrade

without removing the VMA

Y Y Y Provides standard measure of

control loop performance over

time
Y Y N/A
Y Y Y
Y Y Y Only for single duct applicatio ns

Y Y Y Allows air handler reset an d flow

diagnostics
Y Y Y Indicates shaft slippage

VMA1400 Series Overview and Engineering Guidelines Technical Bulletin 5

VMA Features (Cont.) 1410 1420 1430 Comments

Commissioning

Balancing Tool with Automatic

Pickup Gain Calculation

Hardware

24 Volts Alternating Current (VAC)

Isolation Built-in

Multiple VMAs per 100 VA

Transformer

Isolated N2, Binary Outputs, and

24 VAC

Ability to Drive Low Current Relays

Down to 25 milliampere (mA)

15 Bit Analog Input/12 Bit Analog

Output Resolution

Analog Input Jumpers Eliminated

Differential Pressure Transducer

Dead Ended Transducer
Stainless Steel Capacitive

Technology

Industry Accepted Flow

Measurement Accuracy

Temperature Sensors

Variety of Sensors

Temporary Occupied Button

Temporary Occupied Light-Emitting

Diode (LED)

LED Indicator for N2/Power

Physical

Small, One Piece Assembly:

VMA1410, VMA1420

152.4 x 101.6 x 101.6 mm
(6 x 4 x 4 in.)

VMA1430

152.4 x 101.6 x 82.6 mm
(6 x 4 x 3.25 in.)

Plenum Plastic Housing Rating

Removable I/O Screw Terminals

Y Y Y HVAC PRO software (single duct

only) or VMA Balancing Tool

(VBT) software on Zone Bus

Y Y Y Eliminates 24 to 24 VAC

transformer and polarity concerns
Y Y Y Ten cooling only (VMA1410) or

14 VMA1430s. Reheat/fan unit

depends on valve/fan relays
Y Y Y Saves installed cost and improves

electrical noise rejection
N Y Y Eliminates relay chatter

AI
only

Y Y Y Reduces labor because all analog

Y Y Y Requires no filters or maintenance
Y Y Y Provides improved stability

Y Y Y Provides stability below 1 m/s

Y Y Y Nickel, 1 K platinum, silicon,

Y Y Y On TE-6700, TE-7000 (Europe

Y Y Y On TE-6700, TE-7000 (Europe

Y Y Y Verifies N2 and power

Y Y Y Reduces installation cost

Y Y Y Underwriters Laboratories®, Inc.

Y Y Y Two or three position accessories

Y Y Provides improved control device

resolution

inputs are preset

(200 fpm)

2.25K NTC

only), and TMZ1600 Series room

sensors

only), or TMZ1600 for timed

override (Temporary Occupied)

connections

(UL) 94-5VB plenum flammability

eliminates metal box

VMA1400 Series Overview and Engineering Guidelines Technical Bulletin 6

VAV System

Theory of Operation

A VAV air handling system typically consists of a single air handling
unit and multiple terminal units. Terminal units typically consist of a
damper and flow sensing probe installed in an enclosure. VAV
terminal units are also called VAV boxes. VAV systems are
predominantly single duct, but about 15% are dual duct designs.
In either case, the supply air temperature and static pressure of the
air handling unit are controlled by an AHU (Air Handling Unit)
controller, while each zone has its own VMA controller.

The air handling unit typically maintains a static pressure in the range
of 125 to 375 Pa (0.5 to 1.5 inches water column (w.c.) inside the
longest run of duct away from the supply fan. This ensures that each
VAV terminal unit has enough pressure at its inlet to deliver the
maximum required flow of air into the space. The supply temperature
is typically in the range of 7 to 16°C (45 to 60°F) for a single duct
VAV system or the cold deck of a dual duct VAV system. The hot
deck temperature of a dual duct VAV system is typically in the range
of 29 to 49°C (85 to 120°F).

VAV systems are most easily understood by first considering a
cooling-only application. As the zone temperature increases, the VAV
controller opens the VAV box damper to allow more cool air to reach
the space. The volume of air required to maintain a particular zone
temperature setpoint is dictated by the size of the space and the
internal and external heat loads. In addition, since the size of the VAV
box dictates its maximum cooling capacity, a VAV box’s performance
is dependent upon the mechanical engineer’s correct box sizing for
each zone.

Sometimes the size, and thus the capacity, of the VAV box may not
match the zone loads. If the installed unit is too small, insufficient
cooling results and noise may be emitted at high flow. If the installed
unit is too large, proper control may be difficult to attain, since a small
change in damper position causes a large change in airflow. Boxes can
be oversized to allow for quieter operation or reserve cooling capacity
at the expense of controllability.

VMA1400 Series Overview and Engineering Guidelines Technical Bulletin 7

The VMA quickly adjusts the damper position to new conditions, and
minimizes position hunting and motor runtime. The fast response
stepper actuator on the VMA1410 and 1420 drives the damper from
full open to full closed in 30 seconds. This significantly reduces the
time to commission a VAV box. Response time of the VMA1430 with
an external synchronous actuator is dependent upon the speed of the
actuator used. The VMA incorporates flow feedback to accurately
position the damper. Control performance metrics are recorded and are
available via the Metasys Operator Workstation (OWS) for timely
indication of system problems.

The VMA is configured for most VAV applications. Configuration
Tools (HVAC PRO software), Version 7.00 or later builds the
applications for VMA1410/1420. Version 7.02 or later includes the
VMA1430 as well as the VMA1410/1420.

VMA1400 Series Overview and Engineering Guidelines Technical Bulletin 8

V

V

Ethernet LAN

Network

Control Unit

(NCU)

DX9100

TC9102

Unitary

Controller

(UNT)

Palm Compatible
Handheld Device

CVTPRO
Converter

Network

Control

Module

N30

N30

(NCM)

MA1400

Operator Workstation

DX9100

AHU

VAV

UNT

MA1400

UNT

VMA1400

N2

Zone

N2

CablePRO

Converter

Laptop

Room

Bus

Room

Sensor

Sensor

™

Zone

Bus

VMAMTSY6

Figure 2: VMA in Metasys Network Diagram

VMA1400 Series Overview and Engineering Guidelines Technical Bulletin 9

Definition of Terms

Autocalibration

To correct for pressure sensor drifts over time, the VMA has an
Autocalibration mode that automatically compensates for temperature
and humidity effects.

N2 Switches

Single-pole, single-throw switches used to set the N2 address of a
controller.

Room Schedule

A set of information listing all parameters required in a room or zone.

Test and Balance (TAB)

Test and Balance (TAB) is a function performed to ensure the installed
system operates to design specifications. Balancing of the VMA zone
indicates whether the VAV terminal box is able to achieve
minimum/maximum airflow settings. TAB must also be performed for
the air handler and the air duct distribution to the VAV box.

Zones

When designing VMA systems, it is critical to establish zones
correctly to take full advantage of VMA’s exceptional accuracy and
rapid response capabilities.

The designer strives for the most uniform indoor environmental
conditions possible. A single thermostatic device (room sensor)
controls each area. Also, you may consider a zone any area where the
load is approximately the same for every square foot of floor space.

Heating, Ventilating, and Air Conditioning (HVAC) system zones fall
into two major categories: exterior zones and interior zones. Exterior
zones are spaces directly affected by outdoor weather conditions.
Interior zones are not influenced by heat losses or outdoor air
conditions. Interior zones usually have cooling or ventilation
requirements only.

Further division of interior/exterior zones is occasionally required to
accommodate different occupancy schedules and/or solar loads.
Variations in internal loading also dictate the selection of separate
zones. For example, in a restaurant, the kitchen has much different
heating and cooling requirements than the customer seating area.

VMA1400 Series Overview and Engineering Guidelines Technical Bulletin 10

Room Sensor Placement

When considering room sensor placement for each zone:

• Verify that the room sensor is the correct one for the
application.

• Review architectural requirements such as furniture height and
location, aesthetics, and type of mounting. Wall plates are
required if mounting on a conduit handibox.

• Review room sensor location. The best room sensor location is
on an interior wall, about 1.5 m (5 feet) above the floor, out of
direct sunlight, out of the direct path of supply air from the
diffuser, away from heat sources, such as equipment, machines,
and perimeter radiation, and away from doors and other draft
sources. Local codes or disabilities act requirements
occasionally influence the actual mounting height.

• Do not locate a sensor near zone boundaries, where primary
influence is from an adjacent zone.

Pressure Independence

The pressure independent VMA employs patented self-tuning,
cascaded proportional/integral control loops. The zone temperature
loop samples space temperature and resets the airflow setpoint
between the minimum and maximum flow settings. Since inlet duct
static pressure influences the amount of air passing through the VAV
box, the VMA airflow loop samples airflow via a flow pickup in the
box inlet. It modulates the damper to control the flow. Thus, the
VAV box flow is independent of duct static pressure.

The engineering basis for this method of control is that the temperature
of a space with a constant load is linearly proportional to the flow of
conditioned air into the space. The engineer must accurately determine
the required maximum and minimum flow for each space based on
heating, cooling, and ventilation loads.

VMA Airflow Rate

The VMA determines airflow rate by dynamic pressure measurement.
The VMA contains a Differential Pressure Transducer (DPT) to sense
velocity pressure in pressure independent VAV applications.

The DPT is connected to the VAV box airflow pickups. It measures
velocity pressure and generates a proportional voltage signal. The
VMA reads voltage signal from the DPT and converts it to airflow in
cubic feet per minute (cfm), liters/second, or cubic meters/hour.
Calibration is not required, with the exception of zero calibration,
which the controller performs automatically as set in the configuration.

VMA1400 Series Overview and Engineering Guidelines Technical Bulletin 11

The DPT provides maintenance-free performance within the control
range of 1 to 18 m/s (200 to 3500 feet per minute [fpm]) when used as
recommended.

Pressure independent VAV terminal boxes use an airflow pickup
device, which amplifies the airflow velocity pressure between 1.5 to
3 times (varies by manufacturer). The airflow velocity and the gain of
the airflow pickup produce an accurately measured pressure
difference.

The VMA Autocalibration function helps reduce the temperature
effect error by zeroing offset errors. As the ambient temperature
swings relative to the temperature at which the Autocalibration
occurred, an offset error occurs. In the worst case, the offset error
ranges up to ±0.179 Pascal per °C (±0.0004 inch w.c. per °F).
When calibration occurs, this error becomes zero.

The error envelope becomes smaller with increased airflow pickup
gain and with smaller ambient temperature deviations at the
transmitter location.

Power Source

You can use one 24 VAC power trunk to power multiple VMAs.
Transformers of up to 100 VA can be centrally located and the
secondary run can be without conduit (if allowed by local authority)
and without concern about polarity. When using a single transformer
to power multiple VMAs, use a wire gauge large enough to handle the
current and minimize the voltage drop. The voltage drop depends on
the current draw, wire gauge, and wire length. For more details about
transformer wiring and calculating the number of VMAs per
transformer, see the Mounting and Wiring Variable Air Volume

Modular Assembly (VMA) 1400 Series Controllers Technical Bulletin
(LIT-6363125).

Note: The 24 V power transformer must be UL/Canadian
Standards Association (CSA) listed as NEC Class 2 Power Limited.
See NEC Article 725/Class 2 (30 VRMS maximum) and
(100 VA maximum).