VMA 1400 Series Selection Guide
The Variable Air Volume Modular Assembly (VMA) 1400 Series is a family of configurable digital VMA controllers manufactured by Johnson Controls. Each model in the VMA 1400 Series features an integrated module that includes a differential pressure sensor, a pre-wired controller, and/or a damper actuator housed in a pre-assembled unit.
The VMA 1400 Series is used to enhance the operation of Variable Air Volume (VAV) systems. A VAV system is an air handling system consisting of multiple terminal units and a single air handling unit. The VAV terminal units, also known as VAV boxes, typically consist of a flow sensing probe and a damper installed in a protective enclosure.
Predominantly, VAV systems are designed as single-duct systems, but approximately 15% of the available VAV units are designed as dual-duct. In either case, an Air Handling Unit (AHU) controller is used to control the static pressure and supply air temperature of the VAV’s air handling unit, while each zone includes its own VMA module.
VMA 1400 modules are available in four models, namely:
- VMA 1410 Model: It includes an integrated actuator in addition to a pressure differential sensor and controller. This model is designed for pressure-independent, single-duct cooling applications only.
- VMA 1420 Model: It includes an integrated actuator, as well. The VMA 1420 model is designed for single-duct and dual-duct pressure independent VAV systems. It is ideal for cooling and reheating applications and can be used with series or parallel fan-powered VAV boxes.
- VMA 1430 Model: This model requires an external proportional or incremental actuator for use with the integrated controller and differential pressure sensor. Like the VMA 1420, the VMA 1430 is also designed for pressure-independent, single-duct and dual-duct VAV applications, and it can be used with series or parallel fan-powered VAV terminal units.
- VMA 1440 Model: This model is designed for single-duct, pressure-independent VAV systems.
Selecting a VMA 1400 Module
The unique features and functionalities of the VMA 1400 Series significantly reduce installation and commissioning time while enhancing the performance and operation of Variable Air Volume systems, making it the product line of choice for most VAV systems. Therefore, selecting a VMA 1400 module with the right components, features, and accessories is crucial in meeting the control requirements of a given VAV system.
Outlined below are some of the key components and features to evaluate when selecting a VMA 1400 module:
1. Integral Damper Actuator
If you’re considering using a VMA 1400 module with an integrated damper actuator for faster response times, then select a VMA 1410, VMA 1420, or VMA 1440 model. These three models include an integrated damper actuator with a fast-response stepper motor that is characterized by high precision (23K resolution) and low noise levels (<35 dBA).
The integrated stepper motor actuator drives the VAV damper from a fully open to a fully-closed state in 30 seconds. As a result, the time needed to commission and balance a VAV terminal unit is significantly reduced. Also, the integrated stepper motor can quickly and accurately adjust the position of the VAV damper in response to new conditions presented by the VAV system. This minimizes position hunting, as well as motor runtime.
Thus, to provide a fast and accurate method of controlling the VAV system damper, select a VMA 1400 model whose integrated damper actuator is coupled to a stepper motor. The stepper motor should be rated for the correct input voltage and with a sufficient current to control the VMA damper actuator as required.
If you select a VMA 1400 model with an integrated stepper motor damper actuator such as the VMA1410/1420/1440, ensure that the selected VMA 1400 model is programmed to perform an autocalibration procedure at startup.
The autocalibration procedure ensures that the stepper motor is synchronized, and it also corrects for pressure sensor drift. Initial autocalibration requires the stroke time of the integral damper actuator to be calculated as per the time needed to rotate the VAV damper from the fully open end-stop to the fully closed end-stop. For correct operation, the VMA 1400 modules require physical end-stops on both rotation ends. Check that the calibrated initial stroke time of the integral actuator is equal to either of the following:
- 15 seconds for 45-degree VAV dampers
- 20 seconds for 60-degree VAV dampers
- 30 seconds for 90-degree VAV dampers
Note: If you select a VMA 1420 with an integral actuator for a dual-duct VAV application, be sure to use the VMA 1420 module on the cold deck damper.
3. External Damper Actuator
To use a VMA 1430 model, you will need to select an external synchronous damper actuator. This is because the VMA 1430 is designed for use with an external floating, 3-wire incremental (Position Adjust Output [PAO]) or proportional damper actuator.
Thus, the response time of a VMA 1430 module depends on the speed of the selected external damper actuator. For this reason, the VMA 1430 model should incorporate flow feedback for accurate positioning of the damper in the VAV terminal unit.
Note: External damper actuators for VMA 1430 modules require stroke time configuration to operate properly.
4. Supply Voltage Requirement
All VMA 1400 Series models require a supply voltage of 20 to 30 volts AC (VAC) at an input frequency of 50 or 60 Hz (hertz). The VMA 1410, VMA 1420, and VMA 1440 models have a maximum power consumption rating of 10 VA (volt-amperes) excluding the relay and valve power requirements, whereas the VMA 1430 model has a maximum power consumption rating of 3 VA when the power requirements of the external damper actuator, valve, and relay are not included. Therefore, select the VMA 1400 model whose power requirements are within the power range of your VAV system.
You can configure VMA 1400 controllers for most single-duct and dual-duct Variable Air Volume (VAV) applications. However, you need to identify the additional components required when a given VMA 1400 model is configured for a specific VAV application.
For example, to configure the VMA 1420 module for dual-duct or supply/exhaust Variable Air Volume applications, the module requires an additional damper actuator and a Differential Pressure Transducer (DPT) sensor. Similarly, the VMA 1430 model can be configured for dual-duct or supply/exhaust VAV applications, but it would require two external damper actuators and an additional DPT sensor.
6. Balancing Tools
Ensure that you select a VMA 1400 controller with two balancing tool options for faster and more accurate VMA balancing. One of these balancing tools is the HVAC PRO Commissioning Tool. This balancing tool enables users to quickly make adjustments to the VMA 1400 controllers without the need of accessing configuration data. It provides flow (cfm) data, controller parameter information including the area of the VAV box, and a pickup gain that is automatically calculated.
7. Network Communication
Select a VMA 1400 module that can be used in a Metasys network. Network communications generally enable the integration of controllers into a Building Automation System (BAS) for more functionalities. In particular, users can realize even greater benefits from their VAV systems when VMA 1400 controllers are part of a larger Metasys network serving a building facility. This is because the Metasys network provides a more complete building control solution that accommodates energy savings strategies and indoor air quality concerns.
In a Metasys network system, the VMA 1400 controllers connect to the Metasys N2 bus and
a supervisory controller, like the N30 series or a Metasys network control module. The N2 communication bus is a local network interface that links the supervisory controllers (network control module or N30) with all point interfaces or rather application-specific controllers in a Metasys network, such as a Variable Air Volume Modular Assembly (VMA), Air Handling Unit (AHU), Variable Air Volume (VAV), or Unitary controllers. It uses a subordinate/manager communication protocol, in which the supervisory controller (NCM or N30) initiates all communications with the N2 bus devices (i.e., VMA 1400 controllers).
Note: Since the VMA 1400 Series is self-terminating, there are no End-of-Line (EOL) jumpers to be set. However, you will be required to set one EOL jumper for each VMA 1400 N2 bus, typically at the N30 or NCM supervisory controller. Also, with Metasys network configuration, you can plug a laptop directly into the N30 or NCM supervisory controller to monitor the VMA 1400 module on the N2 bus without the need for additional converters.
8. Room Sensor
When used in a Metasys network, VMA 1400 modules require a room sensor as an accessory. Thus, you’ll need to select a room sensor that’s compatible with the VMA 1400 model in use and which is correct for the given VAV application. Also, choose the right connectors for establishing connections between the VMA 1400 module and the selected room sensor.
The available room sensors for use with the VMA 1400 Series include:
- TMZ1600: This room sensor allows users to use a pushbutton keypad to select a timed override occupancy mode, change temperature setpoints, and view the surrounding air temperature. VMA 1400 controllers connect to this room sensor via an 8-pin phone jack. The TMZ1600 room sensor also supports 6-pin phone jack connections for downloading, commissioning, and balancing VMA applications on a laptop.
- TE-7710: It allows users to select a timed override operating mode and change common temperature setpoints.
- TE-6700: This series offers room sensor models with screw terminal connections and an 8-pin phone jack or a 6-pin phone jack. Users can connect a laptop via the 6-pin phone jack to download, balance, and commission VMA applications.
- TE-7720 RF: This is an RF receiver that connects to the VMA 1400 controllers through a 2-wire power cable and an 8-pin phone jack.
- TE-7000 (in Europe only): VMA 1400 controllers connect to this room sensor via a 4-pin jack. Also, using this jack, users can connect a laptop to download, balance, and commission VMA applications.
9. Communication Interfaces
Select a VMA 1400 model that can support the following communication interfaces:
Zone Bus: This is a 2-wire communication bus that enables a computer to balance and commission a VMA 1400 database. The computer used should contain proper VMA commissioning and balancing software, and it should connect to the VMA 1400 module through a CVTPRO (AS-CVTPROx00-x) converter or CablePRO (AS-CBLPRO) converter and a room sensor via the Zone Bus. The Zone Bus is also used to supply 15 VDC input voltage to the CVTPRO converter or CablePRO converter from the VMA 1400 module.
CablePRO Converter: This is a communication interface device used between the VMA 1400 module and a commissioning computer or compatible handheld device. It is used for VAV box commissioning or balancing via the Zone Bus communication port located on the room sensor.
When used with a VMA 1400, the CablePRO converter is purely an electrical interface between the VMA 1400 module and the RS-232 serial port of the commissioning computer. As previously stated, this converter operates on 15 VDC drawn from the connected VMA 1400 and provided through the Zone Bus connector. The data transfer speed on both the Zone Bus and the RS-232 serial port is 1200 bits per second (baud).
Ensure that the CablePRO converter selected for use with a VMA 1400 is supplied with a DB25 or DB9 connector for connecting the VMA 1400 module to the RS-232 COM port of the commissioning computer. Also, the converter should include diagnostic LEDs for indicating the status of the Zone Bus communications. These LEDs should only flash when the VMA 1400 controller is receiving or transmitting data.
CVTPRO Converter: This is an N2/Zone Bus interface device also used between the VMA 1400 module and a commissioning computer or compatible handheld device. It is used for commissioning or balancing VAV boxes through the Zone Bus communications port on the room sensor.
When used with a VMA 1400 module, the CVTPRO converter functions exclusively as an electrical interface between the Zone Bus and the RS-232 serial port of a compatible handheld device. The CVTPRO also operates on 15 VDC supplied by the connected VMA 1400 module through the Zone Bus phone jack. Similarly, if a CVTPRO converter is used, the data transfer rate on both the Zone Bus and the RS-232 port should be 1200 baud.
10. Supported Inputs and Outputs
Select a VMA 1400 controller model that has the appropriate type and number of inputs and outputs to accommodate the load requirements of your VAV system. Also, be sure to check the type of connectors to be used with these inputs and outputs. VMA 1400 controllers support the following inputs and outputs:
Analog Inputs: VMA 1420 and VMA 1430 models support one (1) internal and four (4) external analog inputs, while the VMA 1410 model provides one (1) internal and two (2) external analog inputs. These analog inputs are preset for either voltage or temperature/setpoints. They do not require any jumpers.
Binary Inputs: All VMA 1400 models provide three (3) dry contact binary inputs (BIs). Zone bus commands override binary input BI-1 when a VMA 1400 is used with some room sensors like TE-7700 RF, TE-6700, or TE-7000.
Analog Outputs: VMA 1420, VMA 1430, and VMA 1440 models support two (2) analog outputs, whereas the VMA 1410 does not support any analog outputs. Each analog output on the VMA 1430/1420/1440 generates a proportional output voltage ranging between 0 and 10 VDC. A load should be connected between the analog output terminal and the analog output common terminal.
Note: The two analog outputs available in the VMA 1430 model are used for either proportional reheat valves or proportional external damper actuators, where one analog output is used to connect to each proportional actuator.
Binary Outputs: The VMA 1410 does not provide any binary outputs, whereas the VMA 1430/1440/1420 models provide five (5) external 24 VAC Triac binary outputs. Each VMA load connects between the binary output terminal and the binary output common terminal. However, the integrated damper actuator in the VMA 1410, VMA 1440, and VMA 1420 wires internally to these modules.
On the other hand, an external incremental floating, 3-wire damper actuator is wired externally to two of the five binary outputs on the VMA 1430 module. The remaining three binary outputs of the VMA 1430 module can be used for VAV box heating, supplemental heating, fan connection, and lighting.
11. Power Source
You can power multiple VMA 1400 modules using a 24 volts AC (VAC) power source, or by using a 100 VA (volt-ampere) transformer.
If you decide to use a single transformer to power multiple VMA 1400 modules, ensure that you select a wire gauge that is large enough to handle the enormous current draw and minimize the possible voltage drop. The voltage drop value will depend on the amount of current being drawn and the wire length, as well as the wire gauge.
Note: The 24 VAC power source selected for powering VMA 1400 modules should be listed as NEC Class 2 Power Limited in compliance with Canadian Standards Association (CSA)/UL standards.