Viconics VBZS Guide Specifications

Viconics BACnet Zoning System Engineering Guide

Specification

Viconics BACnet Zoning System Engineering Guide Spec

1.01 System Description – The Viconics BACnet Zoning System (VBZS) shall provide a simple and

efficient demand based system for the operation of changeover bypass or pressure dependent type
zoning systems utilizing standard 2 heat / 2 cool configurations, 2 heat / 2 cool with economizer and IAQ,
analog heat/2 cool, or heat pump 3 heat/ 2cool. The system shall consist of two primary components as
manufactured by Viconics: A communicating rooftop unit controller / heat pump controller (model
VZ7656x1000B) and one/several communicating zone controllers (model VZ7260x5x00B). A local
BACnet MS_TP communication bus between all devices shall ensure proper communication and data
exchange of all required information between the zone controllers and the rooftop unit controller for
proper system operation. The system shall seamlessly integrate into any 3rd party BACnet supervision
system adding greater functionality without being limited to a single vendor. Controls that can only be
integrated into a proprietary non-open protocol network shall not be acceptable. All system configuration
tools shall be embedded within the local devices via real text configuration interface. Systems requiring
external tools for commissioning or configuration shall not be acceptable.

1.02 Quality Assurance - The control system shall be manufactured within a systems certified ISO-9001
and ISO-14001. Please see the Equipment section for industry approvals and specifications.

Part 2 – Equipment

2.01 General - The VZ7656x1000B Rooftop controller shall be designed for equipment control based on
heating and cooling demands from the zone controller(s) (VZ7260). The packaged rooftop or heat
pump system controller VZ7656 shall also provide logic and required inputs/outputs to control system

specific static pressure. The VZ7260F5x00B zone controllers shall be designed for local pressure
dependent VAV control.

Communication Protocol – The control system shall communicate using the open-protocol BACnet
MS_TP over RS485. Zone controls shall be configured directly from the local keypad to communicate with
a specific Rooftop Unit controller. All zone and Rooftop Unit controllers must reside on the same network.
All controllers in the network shall communicate at the same baud rate in order to properly exchange
information. Baud rate for system shall be set at Rooftop/system controller (VZ7656). Zoning control
controller shall feature “Auto-baud capability” allowing system baud rate configuration from Rooftop
controller to be matched by zoning controller(s) thereby facilitating system configuration and
commissioning.

Scalability – The system shall be fully scalable in terms of number of zone controllers and Rooftop Unit
controllers used on the same BACnet MS_TP communication trunk. A segment shall be a shielded
network loop run between all communicating device connections. The segment shall be no longer than
1200 meters (4000 feet). A single network segment shall be capable of installing up to 64 nodes (of either
type of controller). To install more than 64 nodes or if the network wire loop is longer than 1200 meters

(4000 feet), repeaters shall be used to ensure proper communication. With repeaters and a BACnet
MS_TP supervisory system, the maximum number of nodes on a single BACnet MS_TP trunk can be
extended to 128 nodes (of either type of controller).

Overall system architecture shall be open-standard based upon Building Automation Control network
(BACnet) standard facilitating the future replacement or addition of other system components, quickly and
easily. System functionality shall be scalable to suit current and future building automation needs with
simple addition of other BACnet based building controllers. System shall support supervisory functionality
(supplied by others) which will support centralized scheduling, alarming and trending found commonplace
amongst today’s advanced automation systems.

Systems not capable of supporting supervisory BACnet workstations shall not be acceptable.
Communication Wiring and Layout – The wire shall be a balanced 22-24 AWG twisted pair with a

characteristic impedance of 100-130ohms, capacitance of 17 pF/ft or lower, with a braided shield. The
RS485 network requires a daisy chain configuration. A BACnet MS_TP network must be properly
terminated at each end of the daisy chain with an EOL (End of line) resistor. The polarity of the network
connections must be respected.

Functionality – The VBZS shall be capable of operating without external input from a supervisory
system. The control system however, shall be capable of communicating with any 3rd party BACnet
MS_TP compatible supervisory system, graphic user interface, charts and log software, advanced energy
management software, automatic response to alarms etc.

VZ7656x1000B BACnet Rooftop or Heat Pump Controller

The Rooftop unit Controller shall be:

VZ7656R1000B: Up to two heating and two cool stages, single fan speed output, 0-10Vdc output for

bypass damper or variable-frequency drive (VFD).
VZ7656F1000B: Modulating 0-10Vdc heating / 2 cooling stages, single fan speed output, 0-10Vdc output

for bypass damper or variable-frequency drive (VFD).
VZ7656E1000B: Up to two heating and two cooling stages, single fan speed output, 0-10Vdc output for

economizer actuator, 0-10Vdc output for bypass damper or variable frequency drive (VFD), indoor air
quality sequence (IAQ)

The Heat Pump Controller shall be:
VZ7656H1000B: 2 stage compressor with reversing valve and auxiliary heat, single fan speed output, 0-

10Vdc output for bypass damper or variable-frequency drive (VFD)

General VZ7656 Specifications:

VZ7656 controller shall be capable of controlling single or multistage HVAC units with automatic

changeover based on zone demands using the BACnet MS_TP communication protocol on
RS485.

The controller shall have the option of analyzing the PI heating or PI cooling demands from the

zones the following ways depending on the application:

1. Highest: The highest PI heating or PI cooling demand from the selected
voting zones shall dictate heating or cooling operation of the Rooftop Unit
controller.

2. Average of the three (3) highest demands: The average of the three (3)
highest PI heating or PI cooling demands from the selected voting zones will
dictate heating or cooling operation of the Rooftop Unit controller.

3. Average of the five (5) highest demands: The average of the five (5)
highest PI heating or PI cooling demands from the selected voting zones will
dictate heating or cooling operation of the Rooftop Unit controller.

The controller shall be capable of maintaining the system static pressure set point using

integrated proportional static pressure logic to modulate a bypass damper. A pressure transducer
with a 0-5Vdc output shall be wired directly to the VZ7656 controller. The controller shall have an
adjustable static pressure sensor range from 0-5” W.C. The control will output an analog signal
from 0-10Vdc to the bypass damper. A control system requiring a separate bypass damper
controller or separate sensors to display the bypass damper position is not acceptable.

The controller shall have EEPROM memory to prevent a loss of programming due to power

outage as well as a minimum of 6-hour reserve time for the internal clock.