Trane VariTrac User Manual
Controller
Operator Guide
VariTrac
Central Control Panel
TM
VAV-SVU01A-EN
VariTrac Central Control Panel Operation Guide
This guide and the information in it are the property of American Standard
Inc. and shall not be used or reproduced in whole or in part, except as
intended, without the written permission of American Standard Inc. Since
Trane has a policy of continuous product improvement, it reserves the right
to change design and specification without notice.
Use of the software contained in this package is provided under a software
license agreement. Unauthorized use of the software or related materials
discussed in this manual can result in civil damages and criminal penalties.
The terms of this license are included with the compact disc. Please read
them thoroughly.
Trane has tested the system described in this manual. However, Trane does
not guarantee that the system contains no errors.
Trane reserves the right to revise this publication at any time and to make
changes to its content without obligation to notify any person of such
revision or change.
Trane may have patents or pending patent applications covering items in
this publication. By providing this document, Trane does not imply giving
license to these patents.
The following are trademarks or registered trademarks of Trane: Comfort
Manager, Reliatel, Tracker, Trane, VariTrac, VariTrane, and Voyager.
Windows is a registered trademark of Microsoft Corporation.
Printed in the U.S.A.
© 2002 American Standard Inc. All rights reserved.
VAV-SVU01A-EN
Contents
Chapter 1
Chapter 2
Chapter 3
About This Guide .................................................. 1
VariTrac CCP Naming Conventions ...............................................................1
Cautionary Statements ..................................................................................2
Related Literature ...........................................................................................2
VariTrac History .................................................... 3
Feature Summary ................................................. 5
New Features.................................................................................................. 5
Functional Enhancements .............................................................................6
Increased Zone Count.............................................................................. 6
Discharge Air Control...............................................................................6
Supply Air Tempering............................................................................... 6
Feature Summary .................................................................................... 6
CO2 Based Demand Control Ventilation..................................................6
Zone Occupied Standby Function .......................................................... 6
System Balance Mode .............................................................................6
VAV-SVU01A-EN
Chapter 4
Chapter 5
Global Sensor Setpoint Limit Set-up ......................................................6
Software Change History ..................................... 7
General Information ............................................. 9
Central Control Panel ..................................................................................... 9
Communicating Sensor–Bypass Control Assembly..................................... 9
Bypass Damper(s) ........................................................................................ 10
Zone Damper with a UCM and Zone Temperature Sensor ........................ 10
i
Table of Contents
Chapter 6
Sequence of Operation....................................... 11
Central Control Panel ................................................................................... 11
CCP Start-up ........................................................................................... 11
Bypass System Calibration ................................................................... 11
Static Pressure Bypass ..........................................................................12
Heat/Cool Mode Decision for Zones .....................................................12
Zone Voting for System Heat or Cool ................................................... 13
UCM Zone Tagging for No Vote .............................................................13
Zone Heat/Cool Call Strength ................................................................ 14
Heat/Cool Decision for the CCP ............................................................. 14
Heat/Cool Changeover for the CCP ....................................................... 15
Heat/Cool Changeover from Opposite Strong Callers ......................... 15
Heat/Cool Staging and Discharge Air Control ...................................... 15
Morning Warm-Up/Precool Mode .........................................................16
Manual Heat/Cool Mode Control ..........................................................16
Priority Shutdown.................................................................................. 17
Voyager/Reliatel Rooftop Operation versus Binary Output Control ... 17
2 Heat/2 Cool versus Heat Pump Operation ......................................... 18
Spare Binary Output Control ................................................................. 18
Auxiliary Heat Lockout........................................................................... 18
Occupied Priority Local Heat ................................................................. 18
Unoccupied Priority Local Heat............................................................. 19
Unoccupied Control ............................................................................... 19
VariTrac CCP Group Functions ..............................................................20
Group Occupied/Unoccupied ........................................................ 20
Timed Override ...............................................................................21
Group Overrides .............................................................................21
System Balance Mode ...........................................................................22
CO2 -Based Demand Control Ventilation............................................... 22
Global Sensor Setpoint Limit Setup ..................................................... 23
ii
VAV-SVU01A-EN
Chapter 6
cont’d
Unit Control Module (UCM)......................................................................... 23
UCM Start-Up......................................................................................... 23
Setpoints ................................................................................................ 24
Parameters ............................................................................................. 25
Damper Control......................................................................................25
Heat/Cool Mode Decision for Zones .....................................................26
Local Heat Control ............................................................................. 26
Priority Local Heat .................................................................................. 27
Stand-alone Control............................................................................... 27
UCM CO2 Input for VariTrac Demand-Controlled Ventilation .............. 28
Occupied/Unoccupied Mode................................................................. 29
UCM Zone Occupied Standby Function ...............................................29
Drive to Maximum ................................................................................. 29
Override to Unoccupied ........................................................................ 30
Failure Modes.........................................................................................30
UCM Interface ........................................................................................ 30
Zone Sensor Operations ..............................................................................31
Zone Temperature .................................................................................. 31
Zone Setpoint Control ...........................................................................31
Timed Override and Cancel...................................................................31
Modem Interface for Remote Communications ......................................... 32
Modem Requirements for the VariTrac CCP .........................................32
Configuring the External Modem ......................................................... 32
Connecting the Modem to the VariTrac CCP ........................................ 32
Modem Operation.................................................................................. 33
VariTrac CCP Interface ..................................................................................33
CCP Operator Display ............................................................................33
VariTrac PC Software..............................................................................33
Tracker Version 10 Panel ........................................................................ 33
VAV-SVU01A-EN
iii
Table of Contents
Chapter 7
Delivered VAV Operation .................................... 35
What “Delivered VAV” Is ..............................................................................35
What “Delivered VAV” Is Not ....................................................................... 35
System Operating Overview ........................................................................ 36
Zone Count ............................................................................................. 36
Automatic Configuration and Start-up .................................................36
Morning Warm-Up .................................................................................36
Supply Air Temperature Control ............................................................ 36
Supply Air Setpoint Reset...................................................................... 37
Daytime Warm-Up.................................................................................. 37
Unoccupied Control ............................................................................... 37
Supply Air Pressure Control .................................................................. 38
Supply Air Pressure Limiting................................................................. 38
Fan Pressure Optimization .................................................................... 38
Power Exhaust Control ..........................................................................38
CO2 -Based Demand-Controlled Ventilation .........................................39
Chapter 8
System Calibration................................................................................. 39
Zone Occupied Standby Function ........................................................ 39
Global Sensor Setpoint Limit Setup ..................................................... 40
System Balance Mode ...........................................................................40
Using the Operator Display ................................ 41
Overview .......................................................................................................41
Screen Layout............................................................................................... 42
Title Bar .................................................................................................. 42
Navigation Buttons ................................................................................ 42
Selection Buttons ...................................................................................42
Home Screen ................................................................................................44
Operation Screens........................................................................................ 45
Branch Selection Screen........................................................................ 45
iv
VAV-SVU01A-EN
Chapter 8
cont’d
Data Display Screens ...................................................................................46
Data Entry Screens ....................................................................................... 46
Analog Data Entry Screen ..................................................................... 47
Alphanumeric Data Entry Screen.......................................................... 48
Confirmation Screens ..................................................................................49
View Procedures ........................................................................................... 51
Determine Area Temperature.................................................................51
Determine Area Temperature Setting.................................................... 51
Adjust Area Temperature Setting .......................................................... 52
Determine Area Occupancy................................................................... 53
Acquire Detailed Area Occupancy Schedule Status ............................ 53
Override Area Occupancy ...................................................................... 54
Cancel Area Override ............................................................................. 54
Acquire Detailed Area Status and Setup ..............................................53
Alarm Procedures......................................................................................... 54
View VariTrac Diagnostics...................................................................... 54
Schedule Procedures.................................................................................... 61
Change Daily Schedule Name ............................................................... 61
Change Daily Schedule Start and Stop Times ......................................62
Add Member to Daily Schedule ............................................................ 64
Remove Member from Daily Schedule................................................. 65
View List of Daily Schedules and Check Occupancy............................ 66
View a Daily Schedule and Schedule Members ...................................66
View Unscheduled Members ................................................................ 67
After Hours Procedures................................................................................69
Start or Restart an Area Timed Override ............................................... 69
Start or Restart Timed Override of a Single Schedule ......................... 72
Start or Restart All Timed Override Schedules ..................................... 72
Cancel a Single Area Timed Override ................................................... 72
Cancel Timed Override of a Single Schedule ....................................... 73
Cancel Timed Override of All Schedules ...............................................73
VAV-SVU01A-EN
v
Table of Contents
Chapter 9
Advanced Functions ........................................... 75
CCP Setup and Service................................................................................. 75
CCP Setup............................................................................................... 75
Set the Current Time ....................................................................... 76
Set the Current Date ....................................................................... 76
Set the Time Format........................................................................ 77
To Change the Units of Display ..................................................... 77
Service and Testing ................................................................................ 77
Operator Display Parameters.........................................................78
CCP Hardware and Software Functions ........................................ 80
System Setup and Status............................................................................. 83
System Setup .........................................................................................83
System Name.................................................................................. 84
HVAC Unit Type ............................................................................... 84
Control Mode ..................................................................................84
Supply Air Tempering ..................................................................... 84
Discharge Cooling Setpoint ........................................................... 84
Discharge Heating Setpoint ........................................................... 84
Minimum Opposite Callers ............................................................ 85
Minimum Opposite Strong Callers ................................................ 85
Static Pressure Setpoint Multiplier ................................................ 86
System Balance Mode .................................................................... 87
Adjust Groups for Balance Mode ..................................................88
Disabling the System Balance Mode.............................................89
Changing Limits Globally ............................................................... 89
Calibrate Now ................................................................................. 90
System Status ........................................................................................91
vi
VAV-SVU01A-EN
Chapter 9
cont’d
Zone Setup and Status................................................................................. 96
Zone Setup .............................................................................................96
Zone Name...................................................................................... 97
Heat/Cool Vote................................................................................. 97
Use Local Setpoint ..........................................................................97
Flow Override..................................................................................97
Unoccupied Cooling Setpoint ........................................................98
Occupied Cooling Setpoint ............................................................ 98
Occupied Heating Setpoint ............................................................ 98
Unoccupied Heating Setpoint ........................................................98
Zone Sensor Setpoint Limits.......................................................... 99
Cooling High Limit.......................................................................... 99
Heating High Limit.......................................................................... 99
Cooling Low Limit ........................................................................... 99
Heating Low Limit ........................................................................... 99
Airflow Maximum Position .......................................................... 100
Airflow Cooling Minimum Position ............................................. 100
Airflow Heating Minimum Position ............................................. 100
Local Heat Minimum Position (UCM 4.0 and later) .................... 100
Occupancy Sensor Setup (UCM 4.0 and later) ........................... 101
Aux Sensor Set To (UCM 4.0 and later) ....................................... 101
Zone Status .......................................................................................... 102
Group Setup ......................................................................................... 104
Group Name ................................................................................. 105
Vent Mode ..................................................................................... 105
Flow Override................................................................................ 105
Energy Saver Mode ...................................................................... 105
View or Edit Current Group Members ......................................... 105
VAV-SVU01A-EN
vii
Table of Contents
viii
VAV-SVU01A-EN
Chapter 1
About This Guide
This manual describes the steps required to properly set up and operate VariTrac
changeover-bypass variable air volume (VAV) systems, delivered VAV systems,
and the VariTrac central control panel (CCP). The information in this guide
includes:
VariTrac History. A brief overview of the VariTrac product history.
Feature Summary. A summary of the new features and enhancements of
VariTrac (3).
Software Change History. A chronology of version changes to the VariTrac CCP
embedded software.
Introduction to VariTrac. General information about the VariTrac CCP.
VariTrac Operation Overview. Basic operation information covering startup,
heat/cool decisions, zone controller and zone sensor operations, and modem
interface.
Delivered VAV Operation Overview. Basic delivered VAV operation information
covering startup, heat/cool decisions, zone controller and zone sensor operations,
and modem interface.
Using the Operator Display. Information and procedures for navigating through
the operator display menus, including Home, View, Alarms, Schedules, and After
Hours.
Advanced Functions. Information for advanced users, including CCP setup and
service, system setup and status, zone setup and status, and group setup.
VariTrac CCP Naming Conventions
The use of the name “VariTrac CCP” in this manual implies the VariTrac central
control panel and the VariTrac CCP embedded system software. Where
information is unique to one model, that model is specified.
VAV-SVU01A-EN 1
About This Guide
Cautionary Statements
The following cautionary statements signal procedures or conditions that
require particular attention. Personal safety and the proper operation of
the system depend upon the strict observance of these precautions.
WARNING
Indicates a potentially hazardous situation, which, if not avoided, could
result in serious injury or death.
CAUTION
Indicates a potentially hazardous situation, which, if not avoided, may
result in minor or moderate injury.
CAUTION
Indicates a situation in which property-damage-only accidents could occur.
It is also used to alert against unsafe practices.
IMPORTANT
Alerts installer, servicer, or operator to potential actions that could cause the
product or system to operate improperly, but will not likely result in potential for
damage.
Related Literature
The following literature is referred to or pertains to equipment referred to
in this manual.
• VariTrac CCP installation guide, VAV-SVN03A-EN
• VAV UCM installations and operations,VAV-SVX01B-EN
• Voyager service literature
• Reliatel service literature
2
VAV-SVU01A-EN
Chapter 2
VariTrac History
With the introduction of VariTrac in 1989, Trane brought their expertise in variable
air volume (VAV) controls into the changeover-bypass zoning market.
The concept of changeover-bypass zoning brings the flexibility and comfort of VAV
systems into the light commercial unitary market, at an affordable price.
The first generation of VariTrac was a 16-zone pressure dependent system. The
zone dampers featured the same electronic zone controller Trane developed for its
VAV boxes, operating in the pressure dependent mode. The heart of the system
was the Comfort Manager™, a panel which was designed to manage the HVAC
unit, bypass damper functions, and changeover decisions. The functional concept
of this original system continues to be the backbone of today’s zoning system.
In the early 90s, two important enhancements were added to the system:
• Trane’s new Comm4 communications link for the damper controllers
• The ability to directly communicate with Trane’s new Voyager UCP electronic
rooftop unit controls
Trane introduced the second generation of VariTrac in 1995. This generation
featured the central control panel as the functional replacement for Comfort
Manager. The new panel consisted of a resin enclosure, optional relay board for
24 VAC unit control, and a move to static pressure for bypass control. Improved
changeover control was added to the operating system, and the zone damper
controls were upgraded to UCM Version 3.
Trane introduced a new generation of VariTrac controls in 2002. This generation
kept all the great features of the original VariTrac system, plus added new features
and enhancements. The enhancements were designed to make the 2002
generation of VariTrac the simplest changeover-bypass zoning system to install,
commission, and service of any light commercial controls system available today.
VAV-SVU01A-EN 3
VariTrac History
VAV-SVU01A-EN4
Chapter 3
Feature Summary
New Features
CCP with three-piece enclosure design and optional operator display
Quick snap-in optional relay board with easy-to-wire terminal strip
Communicating sensor assembly including a UCM 4 with integral temperature
and pressure sensor, and output to the bypass damper(s)
Bypass damper with factory-installed wiring harness for plug-in connection to
the communicating sensor assembly
Zone dampers with UCM 4 boards and:
– Zone occupancy sensor input
– Zone (carbon dioxide) CO2 sensor input
New rectangular zone dampers (sizes given in inches):
– 8×12, 8×14, 8×16
– 10×16, 10×20
– 14×18
Same Comm4 communications to the zone dampers for reliable operation and
backward compatibility
Supports Comm5 communications to the new Tracker Version 10 panel
Optional touch-screen operator display with built in 7-day time clock
Windows®-based PC software program for system interface
Digital display zone temperature sensor
Pressure-independent box capability
Local heat capability
VAV-SVP01A-EN 5
Feature Summary
Functional Enhancements
Increased Zone Count
The new VariTrac system now supports 24 zones instead of 16. The
zones may be VariTrac dampers, or any type of VariTrane VAV box
including fan-powered boxes or boxes with factory-installed local heat.
Discharge Air Control
VariTrac now does discharge air control. When there is demand for
heating or cooling from a zone, the CCP controls the discharge air
temperature to the discharge air setpoint (default 55°F cooling, 110°F
heating), using as many stages as necessary.
Supply Air Tempering
It is now possible to enable the supply air tempering function in a
Voyager via the CCP. This allows the Voyager to cycle a stage of heat on
and off to warm up the supply air stream and better manage the load
created by increased ventilation air requirements.
CO2-Based Demand-Controlled Ventilation
CO2 sensors can now be connected to VariTrac zone UCMs. The CCP
demand control ventilation will reset the ventilation damper position for
the Voyager/Precedent unit based on the CO2 level.
Zone Occupied Standby Function
A VariTrac UCM can now have an occupancy sensor connected to it. It
can be configured to perform an occupied standby function at the zone
level during the system occupied mode.
System Balance Mode
A VariTrac system can be placed in the balance mode from the operator
display or the PC software using a single button selection. In this mode,
the CCP automatically prepares the VariTrac system for balancing by
starting the supply fan, disabling heating and cooling, closing the bypass
damper, and opening all zone dampers to their maximum position.
Global Sensor Setpoint Limit Setup
The VariTrac CCP allows you to create a single set of limits for the zone
sensor setpoint thumbwheels and broadcasts them to all the zones on
the system at one time by pushing a single button.
VAV-SVP01A-EN6
Chapter 4
Software Change History
New software versions add capabilities and improve existing operation. Each new
software version includes the features of previous versions. Only the latest
software version is shipped in new VariTrac CCP units. Existing units may contain
a previous version.
The following information states the history of VariTrac CCP embedded software
version changes:
Version 4.0.284. Pre-release version of VariTrac (3) central control panel.
Version 4.0.290. First release of VariTrac (3) central control panel.
Version 4.1.296. Second release version of VariTrac (3) central control panel.
Corrected CCP to Voyager Commercial occupancy state sync issue when
power was cycled at the unit but not at the CCP
Corrected CCP to Voyager II slave state sync issue when power was cycled at
the unit but not at the CCP
VAV-SVU01A-EN 7
Software Change History
VAV-SVU01A-EN8
Chapter 5
General Information
The VariTrac comfort control system brings individual temperature control
to each comfort zone in a building while using the same single-zone airconditioning unit. VariTrac varies the flow of supply air to each zone,
providing the heating and cooling capacity required. The VariTrac
changeover-bypass VAV system includes the following components:
• VariTrac central control panel (CCP)
• Communicating sensor–bypass control assembly
• Main supply duct bypass damper(s)
• VariTrac zone dampers with unit control module (UCM) and zone
temperature sensor
Central Control Panel
The CCP provides coordination, monitoring, and diagnostics for the
VariTrac zone-control system. It is responsible for communicating with
the zone dampers to determine space heating and cooling requirements,
and selecting the mode and number of stages for the heating and cooling
unit to meet those needs.
The VariTrac CCP is designed to provide coordinated control of up to 24
VAV zones and one air-handling unit. The CCP can be controlled and
monitored from an upper level system such as a Tracker Version 10.
VariTrac can also function as a stand-alone device with its occupied/
unoccupied function initiated by the time clock built into the CCP
operator display, or by a binary input from an external time clock or other
contact closure.
Communicating Sensor–Bypass
Control Assembly
The communicating duct sensor assembly consists of a static-pressure
sensor, supply-air-temperature sensor, and communicating zone UCM
board combined into one enclosure. This device performs the following
functions:
• Measures the air pressure in the main supply duct
• Monitors the temperature of the air in the main supply duct
• Controls the position of the bypass damper
• Communicates all this information to the CCP
VAV-SVU01A-EN 9
General Information
Bypass Damper(s)
The main supply-duct bypass damper(s) are modulated by the CCP via
the communicating sensor–bypass control assembly to maintain
consistent supply duct static pressure.
Zone Damper with UCM and
Zone Temperature Sensor
The zone damper UCM compares the space temperature to the active
setpoint to determine space requirements, and to the supply air
temperature to determine available heating or cooling. It modulates the
damper to provide the proper amount of heating or cooling air to meet
comfort conditions.
The zone UCM also provides the VariTrac CCP with information about the
current comfort conditions and heating or cooling requirements of the
space.
VAV-SVU01A-EN10
Chapter 6
Sequence of Operation
Central Control Panel
CCP Start-up
The VariTrac CCP executes the following sequence of events on power up:
1 Reads the type of rooftop and automatically configures the panel to control
the unit.
2 Calibrates the bypass control loop. (See Bypass Control, p. 12)
3 Scans all UCMs and collects zone information.
4 Determines the system operating mode (occupied or unoccupied) and
communicates it to all zones (occupied/unoccupied mode).
5 Begins normal operation.
Bypass System Calibration
Upon power-up or a change from the occupied to the unoccupied mode, the
bypass system goes through its calibration procedure. If there are no schedules
(24-hour operation) in the CCP, the system calibrates approximately once every
seven days. During calibration the system performs the following sequence:
1 All zones perform a self-calibration function (UCM reset). This calibrates the
position of the damper blade, and also does a zero-flow pressure transducer
calibration in VariTrane VAV boxes.
2 When zone calibration is complete, all zone dampers modulate to their
maximum-open position.
3 The bypass damper modulates closed; the zero static pressure reading is
taken with the fan off.
4 The system fan turns on. After 45 seconds, the reference static pressure
reading is taken and stored.
5 The bypass damper then modulates to 50 percent, and the zones are re-
leased from their maximum position.
Note: The calibration procedure can be manually started by pushing the
Now
button available on the operator display or via PC software.
Note: During the transition from the occupied to unoccupied mode, the CCP
checks to see if calibration has been performed for any reason during the last 23
hours. If calibration has already occurred, the previously stored values are used.
Calibrate
VAV-SVU01A-EN 11
Sequence of Operation
Static Pressure Bypass
The VariTrac CCP controls the bypass damper(s) using measured duct static
pressure. The central control panel compares the measured static pressure to the
setpoint. This setpoint is determined by taking the reference static determined
during calibration, and multiplying it by the static-pressure-setpoint multiplier
percent edited in CCP Setup.
If the measured static is
percent, the bypass damper is driven towards the closed position.
If the measured static pressure is
bypass damper is driven towards the open position.
The bypass damper remains stationary if the static pressure is in the
The deadband is the area between the static pressure setpoint and the static
pressure setpoint, minus 10 percent.
The bypass damper can be repositioned up to four times per minute. When the
bypass damper is repositioned open, it moves 8 percent each time. When the
bypass damper is repositioned closed it moves 5 percent each time.
If the
static sensor fails
percent and the system continues to operate.
When the zone is
lower
than the static pressure setpoint minus 10
greater
than the static pressure setpoint, the
deadband
, the bypass damper is driven to the fail-safe position of 50
unoccupied,
the bypass damper is driven to 50 percent.
.
Heat/Cool Mode Decision for Zones
The heat/cool control mode for the individual zones is determined by the zone
damper UCM. The central control panel sends the current supply air temperature
to all the zone UCMs approximately once every 15 seconds. The zone UCM
compares the supply air temperature of the system to the individual zone
temperature and the zone setpoint.
If the supply air temperature is:
• less than or equal to the zone temperature, the control action is
• greater than or equal to the zone temperature plus 10°F, the control action is
cool.
heat.
If the supply air temperature is between the zone temperature and zone
temperature plus 10°F, and the zone temperature is:
• above the cooling setpoint, the control action is
• below the heating setpoint, the control action is
• between the heating and the cooling setpoints, the control action remains
unchanged
.
heat.
cool.
VAV-SVU01A-EN12
Zone Voting for System Heat or Cool
Each zone attached to the VariTrac CCP can “vote” for heating or cooling. A zone
is eligible to vote if it:
is in communication with the central control panel.
has a valid zone temperature reading.
is edited to be a voter in the UCM setup.
is not tagged by the central control panel. (See UCM Zone Tagging below.)
Each zone gets one vote. Occupied and unoccupied zones have the same voting
rights.
UCM Zone Tagging for No Vote
A UCM zone is tagged and excluded from the voting decision if the:
VariTrac system is not in morning warm-up or precool.
zone is receiving its desired supply air (heating/cooling).
zone temperature is furthest away from setpoint of all voting zones receiving
the desired supply air.
zone temperature remains three or more degrees away from setpoint for 60
minutes.
A tagged zone continues to operate and communicate normally but cannot vote
for heat or cool. This prevents one zone from driving the comfort of all other
zones if its setpoints or load cannot be satisfied.
The zone becomes an eligible voter when:
it returns to within 1°F of its active setpoint.
the system becomes unoccupied
UCM tagging is disabled.
Tagged zones are displayed in the service summary of the PC software.
VAV-SVU01A-EN 13
Sequence of Operation
Zone Heat/Cool Call Strength
After the heat/cool mode of the zone is decided, the strength of its heating or
cooling call is determined.
• Cool caller. A UCM becomes a “cool caller” if it is a voting UCM and its zone
temperature is more than 1°F above the active cooling setpoint. A UCM loses
its cool caller status if it becomes a non-voter or if its zone temperature is less
than the active cooling setpoint plus 0.5°F.
• Strong cool caller. A UCM becomes a “strong cool caller” if it is a voting UCM
and its zone temperature is more than 2°F above the active cooling setpoint. A
UCM loses its strong cool caller status if it becomes a non-voter or if its zone
temperature is less than the active cooling setpoint plus 1°F.
• Heat caller on a UCM with no local heat or Priority Local Heat edited to
Off. A UCM becomes a “heat caller” if it is a voting UCM and its zone
temperature is more than 1°F below the active heating setpoint. A UCM loses
its heat caller status if it becomes a non-voter or if its zone temperature is
greater than the active heating setpoint minus 0.5°F.
• Strong heat caller on a UCM with no local heat or priority local heat
edited to off. A UCM becomes a “strong heat caller” if it is a voting UCM and
its zone temperature is more than 2°F below the active heating setpoint. A
UCM loses its strong heat caller status if it becomes a non-voter or if its zone
temperature is greater than the active heating setpoint minus 1°F.
• Heat caller on a UCM with local heat and Priority Local Heat edited to On.
A UCM becomes a heat caller if it is a voting UCM, its local heat has not been
disabled by the CCP, and its zone temperature is more than 2°F below the
active heating setpoint. A UCM loses its heat caller status if it becomes a nonvoter or if its zone temperature is greater than the active heating setpoint
minus 1.5°F.
• Strong heat caller on a UCM with local heat and Priority Local Heat edited
to On. A UCM becomes a strong heat caller if it is a voting UCM, its local heat
has not been disabled by the CCP, and its zone temperature is more than 3°F
below the active heating setpoint. A UCM loses its strong heat caller status if it
becomes a non-voter or if its zone temperature is greater than the active
heating setpoint minus 2°F.
Heat/Cool Decision for the CCP
The central control panel scans all zones continuously (once every 10 to 20
seconds) and determines the quantity and the strength of all heating and cooling
calls. At power-up and on transition from unoccupied to occupied, the greater
number of heat or cool calls determines the mode of the CCP and the airconditioning system. If the votes are tied, the system defaults to heat.
VAV-SVU01A-EN14
Heat/Cool Changeover for the CCP
After the heating/cooling decision is determined, the VariTrac CCP requires a
minimum number of opposite calls to change over. This is an editable setup
parameter with a range of 1 to 4 (factory default is 2). All current callers must be
satisfied before the system is allowed to change over. A minimum time between
changeovers is enforced. (The editable setup parameter has a range of 10 to 60
minutes; the factory default is 15 minutes.) The counter begins running
immediately after a changeover occurs and must expire before changeover is
allowed. The time remaining on the counter is displayed in the operator display
and PC software.
Example:
is in the heating mode and three zones are calling for heat, all three zones must
be satisfied. The system changes over if two or more zones are calling for cooling
and the changeover timer and all minimum-on/off times are satisfied.
The Minimum Opposite Calls to Changeover is set to 2. If the system
Note: During the unoccupied mode (all groups unoccupied), the Minimum
Opposite Calls to Changeover functions the same as in the occupied mode.
Heat/Cool Changeover from Opposite Strong Callers
A heat/cool changeover also occurs if enough opposite strong callers exist. (See
Zone Heat/Cool Call Strength, p. 14.) Minimum Opposite Strong Calls to
Changeover is an editable setup parameter with a range of 1 to 4 (factory default
is 2). All current mode callers
to changeover and all minimum on/off timers must expire before changeover is
allowed.
do not
have to be satisfied, but the minimum time
Note: During the unoccupied mode (all groups unoccupied) the minimum
opposite calls to changeover automatically changes to one (1), so any opposite
strong caller can initiate a mode change.
Heat/Cool Staging and Discharge Air Control
If all zones are satisfied, the CCP operates the HVAC unit in the fan-only mode.
With a call for heating or cooling from one of the zones, the CCP activates stages
of heating or cooling to satisfy the requirement. (See Zone Heat/Cool Call
Strength and Heat/Cool Decision for the CCP, p. 14.)
The VariTrac CCP controls supply air temperature using a discharge air control
algorithm. The CCP controls to separate cooling (55°F default) and heating (110°F
default) discharge air setpoints.
The control algorithm is both deviation- and time-based. During operation, the
CCP monitors not only the supply air temperature deviation from setpoint, but
also how quickly deviation occurs when a stage is turned off, and how quickly
deviation is recovered when a stage is turned on. This allows the CCP to adjust
the number of stages required and the stage cycle rate for the most consistent
supply air temperature control. The control algorithm always meets the
minimum-on and -off time requirements when adjusting stages.
VAV-SVU01A-EN 15
Sequence of Operation
Table 1: Minimum On and Off Times (in minutes)
2 Heat / 2 Cool Heat Pump
Binary Output Min On / Min Off Binary Output Min On/Min Off
Cool 1 3 min / 3 min Stage 1 3 min / 3 min
Cool 2 3 min / 3 min Stage 2 3 min / 3 min
Heat 1 3 min / 3 min Reversing Valve 4 min / 4 min
Heat 2 3 min / 3 min Auxiliary Heat 2 min / 1 min
After it is energized, a stage must remain on until its minimum-on time is
satisfied. After a stage is turned off, it cannot be turned on again until its
minimum-off time is satisfied.
Morning Warm-Up/Precool Mode
When the first CCP group becomes occupied, the central control panel enters
the morning warm-up/precool mode. This mode holds the ventilation air damper
closed on the HVAC unit until the system restores the zone temperatures to their
occupied setpoints.
On a Voyager/Reliatel unit, the ventilation damper is commanded closed via the
comm link. On noncommunicating HVAC systems (relay board control), the
ventilation damper is controlled by Spare Output Relay 6.
The mode terminates when half of the occupied voting zones are satisfied or
become opposite callers. Morning warm-up also terminates after two hours or if
the system heat/cool mode changes. The spare output is energized during
morning warm-up and de-energized when morning warm-up terminates.
Manual Heat/Cool Mode Control
The CCP allows manual heat/cool mode selection via the operator display or PC
software. The VariTrac system normally operates in the autochangeover mode. If
manual selection of the mode is required, the operator may manually place the
system in the heat, cool, off, or auto mode. The system remains in the selected
mode until it is manually returned to the auto mode.
VAV-SVU01A-EN16
Priority Shutdown
Priority shutdown is initiated by:
a priority shutdown command from Tracker.
closing the CCP priority shutdown input.
failure to detect any communicating zone UCMs.
failure to detect a communicating sensor–bypass control assembly at Address
33 (changeover bypass mode only).
failure of the communicating sensor–bypass control assembly discharge air
temperature sensor (changeover-bypass mode only).
a high temperature input alarm from the Voyager high temperature switch input
or Reliatel options module.
failure to detect any voting zones (all zones tagged as “no vote”).
The VariTrac CCP returns to normal operation when the priority shutdown
condition is corrected.
Priority shutdown forces the following control actions:
• Turns off the main supply air fan (minimum-on time not enforced)
• Disables all stages of heating and cooling (minimum-on time not enforced)
• Disables all VAV local heat, if present
• Disables all VAV parallel fans, if present
• Drives all VAV dampers to the maximum open position
• Drives the bypass damper(s) to 50-percent open
Voyager/Reliatel Rooftop Operation versus Binary
Output Control
The VariTrac CCP automatically recognizes and communicates directly with a
Voyager or Reliatel unit on the communications link. The relay board in the central
control panel is not required.
The VariTrac CCP controls Reliatel or Voyager rooftops directly via a Trane
communications interface (TCI) mounted in the rooftop unit. The CCP
automatically senses whether the Voyager or Reliatel unit is a heat pump.
The VariTrac CCP uses an optional relay board with six binary output relays to
control the stages of heating and cooling, and the supply fan on non-Voyager/
Reliatel air-conditioning units. The same relay board is used for heat-pump and 2heat/2-cool operation. When controlling the HVAC unit with the relay board, the
unit type (heat pump or 2 heat/2 cool) must be selected using the PC software or
operator display. The default is 2 heat/2 cool.
VAV-SVU01A-EN 17
Sequence of Operation
2 Heat/2 Cool versus Heat Pump Operation
The VariTrac CCP automatically determines if it is controlling a Reliatel/Voyager 2
heat/2 cool or heat pump unit and configures the operating parameters (such as
staging and supply air setpoints). Generic units controlled with the optional relay
board must be configured as 2 heat/2 cool or heat pump through the operator
display or PC software. This configures the binary outputs to control in the
appropriate sequence. Proper relay function by mode is identified in the VariTrac
CCP wiring schematic. The system default is 2 heat/2 cool.
Spare Binary Output Control
The sixth binary output on the optional relay board is an SPDT unpowered spare
output relay. An entry in the PC software allows you to choose how the relay is
controlled:
• Ventilation. The spare output controls the outdoor air damper control. The
output is energized when the CCP (all groups) is unoccupied. When the first
group becomes occupied, the CCP enters the morning warm-up/precool mode
and the spare output remains energized. The mode terminates when half of the
occupied voting zones are satisfied or become opposite callers. Morning warmup also terminates after two hours or if the system’s heat/cool mode changes
over. The spare output is de-energized when morning warm-up terminates.
• H/C. The spare output is
energized
•ICS. The state of the relay is controlled by an upper-level system, such as
Tracker or Tracer (currently not supported).
•CO2. The relay is controlled by the CCP demand-controlled ventilation program
and energizes when the CO2 alarm point is reached. This relay function can be
used to reset the position of a ventilation damper on a noncommunicating
HVAC unit based on the zone CO2 level.
when it is in heating.
energized
when the CCP is in cooling and
de-
Auxiliary Heat Lockout
Auxiliary heat on heat pump units can be disabled via PC software. When
disabled, any stages of auxiliary heat are turned off (minimum-on times are
enforced).
Occupied Priority Local Heat
Occupied priority local heat is controlled via a PC software entry. If occupied
priority local heat is enabled, each zone controls the local heat to the heating
setpoint for that zone during the occupied mode. In this mode, the zone heats to
setpoint with local heat first. The zone becomes a heat caller if the space temperature falls more than 2°F below the zone heating setpoint.
If occupied priority local heat is disabled, each zone controls the local heat to the
heating setpoint minus 2°F for that zone during the occupied mode. In this mode,
the zone becomes a heat caller when the space temperature falls more than 1°F
below the zone heating setpoint. If the space temperature falls to more than 2°F
below the zone heating setpoint, the zone heats to setpoint with local heat.
VAV-SVU01A-EN18
Unoccupied Priority Local Heat
Unoccupied priority local heat allows the operator to select a different local heat
function during the unoccupied mode. Although priority local heat control may be
desirable for better comfort control during the occupied mode, it may be
desirable for the HVAC unit to have heating priority to save energy when comfort
is not as critical during the unoccupied mode.
Unoccupied priority local heat is controlled via an entry in the PC software. If
unoccupied priority local heat is enabled during the unoccupied mode, each zone
controls the local heat to the unoccupied heating setpoint for that zone. In this
mode, the zone heats to setpoint with local heat first. If the space temperature
falls more than 2°F below the unoccupied zone heating setpoint, it becomes a
heat caller. Only fan-powered VAV boxes operate their local heat with the main
supply fan off. Unoccupied local heat calls at the zone level will not energize the
main supply fan.
If unoccupied priority local heat is disabled during the unoccupied mode, each
zones controls the local heat to the unoccupied heating setpoint minus 2°F for
that zone. In this mode, the zone becomes a heat caller when the space
temperature falls more than 1°F below the unoccupied zone heating setpoint. If
the space temperature falls to more than 2°F below the unoccupied zone heating
setpoint, the zone heats to setpoint with local heat.
Unoccupied Control
The occupancy of the VariTrac system can be determined one of three ways
(listed in order of priority, high to low):
Tracker Version 10 control
Scheduling via the CCP time clock
Binary input control
When the VariTrac system is scheduled by Tracker or the CCP operator display,
the group scheduling function is available. (See Group Occupied/Unoccupied,
p. 20.)
When all groups are in the unoccupied mode, the CCP begins unoccupied
control.
When the occupancy mode is determined by the occupied/unoccupied binary
input, group scheduling functions are not available. All groups follow the state of
the binary occupied/unoccupied input. When a contact closure is made across
terminals TB2-8 and -9, the unoccupied mode is initiated for all groups and
connected zones.
VAV-SVU01A-EN 19
Sequence of Operation
During unoccupied control, the CCP:
• begins intermittent fan operation. During the unoccupied mode, the fan
operates only on a demand for heating or cooling. This minimizes the fan
operation to save energy.
• changes the minimum number of strong callers for changeover to one.
During the unoccupied mode, the minimum opposite strong calls for
changeover goes to one so any strong caller can change the system over. All
other system setup parameters remain the same during the unoccupied mode.
• disables energy saver and ventilation modes. The energy saver and
ventilation modes require continuous fan operation and are disabled in the
unoccupied mode.
• disables local heat capability at all zones when the fan is off. During the
unoccupied mode local heat is disabled at all zones when the fan in the air
handler is off. When the fan is energized local heat is enabled (unless edited to
disabled in the PC software).
• disables the outdoor air damper with the spare binary output (if the
VariTrac CCP has the optional relay board). Many systems require the outsideair
damper to remain closed during unoccupied operation. The spare binary output
on the optional relay board can disable the outside air damper during the
unoccupied mode.
VariTrac CCP Group Functions
The VariTrac CCP allows four groups of zones to be controlled and monitored
independently. Each group can have up to 24 members. Any zone can be
assigned to any group, but a zone can only be a member of one group at a time.
By default, all 24 zones are assigned to Group 1.
Group Occupied/Unoccupied
Group occupied/unoccupied performs time-of-day scheduling for the VariTrac CCP.
This allows zones serving a specific area to be grouped and scheduled together.
Each air conditioning system controlled by a central control panel can have up to
four separate time-of-day schedules, one for each of the four groups.
If any group is occupied, the central control panel will operate the supply fan and
handle zone voting according to occupied parameters.
All four groups must be unoccupied for the CCP to operate using unoccupied
parameters. Zones that are members of occupied groups control to occupied
setpoints. Zones that are members of unoccupied groups control to unoccupied
setpoints.
VAV-SVU01A-EN20
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