Installation and
Operation
Tracer™ ZN521 Zone Controller
SAFETY WARNING
Only qualified personnel should install and service the equipment. The installation, starting up, and servicing
of heating, ventilating, and air-conditioning equipment can be hazardous and requires specific knowledge and
training. Improperly installed, adjusted or altered equipment by an unqualified person could result in death or
serious injury. When working on the equipment, observe all precautions in the literature and on the tags,
stickers, and labels that are attached to the equipment.
November 2010 CNT-SVX07D-EN
Copyright
© 2010 Trane All rights reserved
This document and the information in it are the property of Trane and may not be used
or reproduced in whole or in part, without the written permission of Trane. 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.
Trademarks
Trane and its logo are trademarks of Trane in the United States and other countries. All
trademarks referenced in this document are the trademarks of their respective owners.
Warnings, Cautions, and Notices
Warnings, cautions, and notices are provided in appropriate places throughout this
document:
WARNING: Indicates a potentially hazardous situation which, if not avoided,
could result in death or serious injury.
CAUTION: Indicates a potentially hazardous situation which, if not avoided,
could result in minor or moderate injury. It could also be used to alert against
unsafe practices.
NOTICE: Indicates a situation that could result in equipment or property-
damage-only accidents.
2 Doc Number (Variable)
Table of Contents
Overview and specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Product description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Storage environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Clearances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Agency listing/compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Additional components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
General wiring information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Input/output terminal wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
AC power wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Communication-link wiring and addressing . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Mounting the controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Location recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Operating environment requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Mounting recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Input/output functions and wiring for typical applications . . . . . . . . . . . . . . . . . 13
Binary inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
BI1: Low-coil-temperature detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
BI2: Condensate overflow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
BI3: Occupancy or generic binary input . . . . . . . . . . . . . . . . . . . . . . . . . . 14
BI4: Fan status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Analog inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
GND: Ground terminals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
ZN: Zone temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
SET: Local setpoint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
FAN: Fan mode input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
AI1: Entering water temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
AI2: Discharge air temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
AI3: Outdoor air temperature or generic temperature . . . . . . . . . . . . . . . 16
AI4: Universal 4–20 mA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Binary outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Generic binary output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Overriding binary outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Wiring requirements and options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Sequence of operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Power-up sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Random start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Occupancy modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Occupied mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
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Unoccupied mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Occupied standby mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Occupied bypass mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Timed override control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Zone temperature control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Cascade zone control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Simplified zone control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Discharge air tempering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Morning warm-up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Morning cool-down . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Heating or cooling mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Entering water temperature sampling function . . . . . . . . . . . . . . . . . . . . . . . 35
Fan operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Exhaust control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Valve operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Modulating valve operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Modulating valve calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Two-position valve operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Isolation-valve operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Two-pipe operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Four-pipe operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Modulating outdoor/return air dampers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
ASHRAE Cycle 1 conformance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
ASHRAE Cycle 2 conformance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Economizing (free cooling) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Two-position control of a modulating outdoor air damper . . . . . . . . . . . . . 39
Face-and-bypass damper operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Face-and-bypass, isolation-valve operation . . . . . . . . . . . . . . . . . . . . . . . 39
DX cooling operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Electric heat operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Baseboard heat operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Dehumidification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Peer-to-peer communication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Unit protection strategies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Smart reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Low-coil-temperature protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Condensate overflow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Fan status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Fan off delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Filter-maintenance timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Freeze avoidance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Freeze protection (discharge air temperature low limit) . . . . . . . . . . . . . 42
4 CNT-SVX07D-EN
Status indicators for operation and communication . . . . . . . . . . . . . . . . . . . . . . 43
Test button . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Manual output test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Service pin button . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Interpreting LEDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Types of diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Table of diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
CNT-SVX07D-EN 5
Overview and specifications
This guide provides installation and configuration information for the Tracer ZN521 zone controller,
as well as a description of its operations. The overview includes a product description,
specifications, and descriptions of ancillary products that may be necessary.
Product description
The Tracer ZN521 is an application-specific controller that provides direct-digital zone temperature
control. The controller can operate as a stand-alone device or as part of a building automation
system (BAS). Communication between the controller and a BAS occurs by means of a LonTalk
communication link, which complies with the LonTalk protocol.
The Tracer ZN521 supports the following equipment:
• Fan coils
• Unit ventilators
• Blower coils
The Tracer ZN521 can be configured to control:
• Tri-state modulating or two-position valves
• Tri-state modulating dampers:
outdoor/return air, and face-and-bypass
• DX cooling (single stage)
• Electric heat (two stages)
It is designed to be field-installed and is sent from the factory unconfigured. Use the PC-based
Rover service tool to configure the controller for specific applications.
Note: For information about using the Rover service tool, see the current version of the Rover
Installation/Operation/Programming guide (EMTX-SVX01).
Storage environment
If a Tracer ZN521 zone controller is to be stored for a substantial amount of time, store it in an indoor
environment that meets the following requirements:
• Temperature: –40° to 185°F (–40° to 85°C)
• Relative humidity: 5–95%, noncondensing
Dimensions
Plastic-cover model dimensions
For complete dimensional drawing, see Figure 1 on page 7.
• Height: 5.375 in. (137 mm)
• Width: 6.875 in. (175 mm)
• Depth: 2 in. (51 mm)
Metal-cover model dimensions
For complete dimensional drawing, see Figure 2 on page 8.
• Height: 9.0 in (25 mm)
• Width: 10.37in. (263 mm)
• Depth: 2.25 in. (58 mm)
6 CNT-SVX07D-EN
Clearances
4 in.
(102 mm)
5.625 in (143 mm)
1 in
(25 mm)
6.875 in
(175 mm)
1 in
(25 mm)
4 in
(102 mm)
4 in
(102 mm)
6.31
(160 mm)
2 in. (51 mm)
5.625 in.
(143 mm)
Overview and specifications
Plastic-cover model (see Figure 1 on page 7)
• Front: 4.0 in. (102 mm)
• Each side: 1.0 in. (25 mm)
• Top and bottom: 4.0 in. (102 mm)
Metal-cover model (see Figure 2 on page 8)
• Front: 24.0 in. (610 mm)
• Each side: 2.0 in. (51 mm)
• Top and bottom: 1.0 in. (25 mm)
Figure 1. Plastic-cover model dimensions and clearances
CNT-SVX07D-EN 7
Overview and specifications
9 in.
(229 mm)
2.25in.
(58 mm)
1 in.
(25 mm)
1 in.
(25 mm)
9 in.
(229 mm)
24 in.
(610 mm)
2 in.
(51 mm)
Clearances
Dimensions
2 in.
(51 mm)
1 in.
(25 mm)
7 in.
(178 mm)
1.875 in.
(48 mm)
0.28 in.
(7 mm)
6.5 in.
(165 mm)
10.25 in.
(260 mm)
width without cover
10. 3 7 i n .
(263 mm)
width with cover
Figure 2. Metal-cover model dimensions and clearances
Agency listing/compliance
CE—Immunity: EN 50082-1:1997; EN 50082-2:1995
CE—Emissions: EN 50081-1:1992 (CISPR 22) Class B
UL and C-UL 916 listed: Energy management system
UL 94-5V (UL flammability rating for plenum use)
FCC Part 15, Class A
ASHRAE Cycle 1 & Cycle 2 control sequences
Additional components
The Tracer ZN521 zone controller requires the use of additional components for monitoring and
proper control of the associated equipment. The use of specific components depends on the
application. These components are not included with the Tracer ZN521 zone controller.
8 CNT-SVX07D-EN
Power transformer
Use a UL-listed Class 2 power transformer supplying a nominal 24 Vac (19–30 Vac) to power both
the Tracer ZN521 zone controller (14
actuators, to a maximum of 12
Water, duct, and outdoor-air temperature sensors
Temperature sensors must be Trane 10 kΩ (at 25°C) thermistors. Entering water and discharge air
inputs may use a sealed temperature sensor (part number 4190 1100).
VA) and its associated output devices, including relays and
VA per output utilized.
Overview and specifications
Binary input switching devices
Occupancy, condensate overflow, low-coil-temperature, and fan status inputs accept switching
devices that may have normally open or normally closed dry contacts.
Output devices
Output devices connected to the Tracer ZN521 binary outputs cannot exceed 12 VA (0. 5 A) current
draw at 24 Vac.
Zone temperature sensors
Ta bl e 1 shows the Trane zone temperature sensors that are supported by the Tracer ZN521 zone
controller.
Table 1. Tracer zone temperature sensor options
Timed
override
Fan Zone
BAS
order
number
4190 1087 Any x
4190 1088 Any x x x x
4190 1090 Any x x x x x
4190 1094 Any x x x
4190 1095
4190 1115 Fan coil x x x x x x x x x x
4190 1116
4190 1117 Any x x x x x x x
Use
Unit
ventilator
Unit
ventilator
High Med Low Auto Off
x x x x x x x x
x x x x x x x x x
Setpoint
thumb-
wheel
Temperature
sensor
buttons
On Cancel
Comm
jack
Valve actuators
Valve actuators cannot exceed 12 VA draw at 24 Vac. For two-position valves, use actuators with
on/off action, and with a spring action that returns the valve to normally open or closed (dependent
on the desired default position). For modulating valve control, use tri-state modulating actuators
with or without a spring return, as required by the application.
Damper actuators
Damper actuators cannot exceed 12 VA draw at 24 Vac. For control of outdoor/return air dampers,
use tri-state modulating actuators that incorporate a spring return.
Zone humidity sensor
For measurement of relative humidity (RH), the Tracer ZN521 requires a zone humidity sensor with
mA output, where 4 mA is 0% RH a nd 20 mA is 100% RH. The controller provides 20 Vdc to
a 4–20
power the zone humidity sensor.
CO2 sensor
For CO2 measurement, the Tracer ZN521 requires a CO2 sensor with a 4–20 mA output, where 4 mA
ppm and 20 mA = 2000 ppm.
= 0
CNT-SVX07D-EN 9
General wiring information
This chapter provides specifications and general information about wiring the Tracer ZN521 zone
controller. The controller requires wiring for:
• Input/output terminals
• AC power to the controller
• Communication-link wiring, if the controller is to communicate with a building automation
system (BAS)
Input/output terminal wiring
All input/output terminal wiring for the Tracer ZN521 zone controller is application specific and
dependant on the configuration of the controller. Input/output terminal wiring must meet the
following requirements:
• All wiring must comply with the National Electrical Code and local codes.
• Use only 18 AWG, twisted-pair wire with stranded, tinned-copper conductors. (Shielded wire
is recommended.)
• Binary input and output wiring must not exceed 1000 ft (300 m).
• Analog input wiring must not exceed 300 ft (100 m).
• Do not run input/output wires in the same wire bundle with any ac power wires.
For application-specific wiring information and diagrams, see “Input/output functions and wiring
for typical applications,” p. 13
AC power wiring
WARNIN G
Hazardous Voltage!
Before making line voltage electrical connections, lock open the supply-power disconnect
switch. Failure to do so may cause death or serious injury.
CAUTION
Proper Grounding Required!
Make sure that the 24 Vac transformer is properly grounded. Failure to do so may result in
personal injury or equipment damage.
Notice:
Avoid damage to the controller!
Complete input/output wiring before applying power to the Tracer ZN521 zone controller.
Failure to do so may cause damage to the controller or power transformer due to inadvertent
connections to power circuits.
Important: Do not share 24 Vac between controllers.
All wiring must comply with National Electrical Code and local codes.
The ac power connections are in the top left corner of the Tracer ZN521 zone controller (see
3).
Figure
10 CNT-SVX07D-EN
General wiring information
24 Vac
transformer
H
N
Figure 3. Connecting ac power wires to the controller
The Tracer ZN521 may be powered by an existing transformer integral to the controlled equipment,
provided the transformer has adequate power available and proper grounding is observed. If you
are providing a new transformer for power, use a UL-listed Class 2 power transformer supplying
a nominal 24 Vac (19–30
the Tracer ZN521 zone controller (14 VA) and its associated output devices, including relays and
actuators, to a maximum of 12
Vac). The transformer must be sized to provide adequate power to both
VA per output utilized.
Communication-link wiring and addressing
The Tracer ZN521 zone controller communicates with the BAS and with other LonTalk controllers
by means of a LonTalk communication link.
Important: For important instructions on network wiring, refer to the Tracer Summit Hardware
and Software Installation guide (BMTX-SVN01A-EN).
Wiring for the communication link must meet the following requirements:
• All wiring must comply with the National Electrical Code and local codes.
• 22 AWG Level 4 unshielded communications wire recommended for most Comm5
installations.
• Termination resistors are required for wiring LonTalk devices communicating on a network. For
specific information about using termination resistors for LonTalk applications, refer to the
Tracer Summit Hardware and Software Installation guide (BMTX-SVN01A-EN).
Each Tracer ZN521 zone controller has a unique 12-character alphanumeric device address for
communicating on a BAS network. This address, referred to as a Neuron ID, is assigned in the
factory before the product is shipped and cannot be changed. Each controller can be identified by
viewing its unique Neuron ID, which is on a printed label attached to the circuit board of the
controller. Additional adhesive-backed, peel-off Neuron ID labels are tethered to the controller for
placing on mechanical prints or unit location worksheets. The Neuron ID will appear when
communication is established with the Rover service tool or a BAS. An example Neuron ID is 0001-64-1C-2B-00.
CNT-SVX07D-EN 11
Mounting the controller
This chapter gives recommendations and requirements for mounting a Tracer ZN521 zone
controller.
Location recommendations
Trane recommends locating the Tracer ZN521 zone controller:
• Near the controlled piece of equipment to reduce wiring costs
• Where it is easily accessible for service personnel
• Where public access is restricted to minimize the possibility of tampering or vandalism
The controller can often be mounted inside the wiring enclosure of the associated mechanical
equipment.
Operating environment requirements
Operate a Tracer ZN521 zone controller in an indoor environment that meets the following
requirements:
• Temperature: from 32°F to 140°F (from 0°C to 60°C)
• Relative humidity: 5–95%, noncondensing
Mounting recommendations
Mounting recommendations are as follows:
Notice:
Leave Controller Cover On
Mount the Tracer ZN521 zone controller with the cover on to avoid the possibility of damaging
the circuit board during installation.
• Mount the controller in any position, other than with the front of the cover facing downward.
• Mount using the two 3/16 in. (4.8 mm) radius mounting holes provided (see Figure 4). Mounting
fasteners are not included.
• Attach the controller securely so it can withstand vibrations of associated HVAC equipment.
• When the controller is mounted in a small enclosed compartment, complete all wiring
connections before securing the controller in the compartment.
Figure 4. Mounting the Tracer ZN521 zone controller
12 CNT-SVX07D-EN
Input/output functions and wiring for typical applications
This chapter provides information about the function of inputs and outputs and examples of wiring
for typical applications. Applications supported by the Tracer ZN521 zone controller are shown in
Ta bl e 2.
Table 2. Typical applications for the Tracer ZN521 zone controller
Application
Multiple fan speed
2-pipe hydronic cooling only x x x x x x
2-pipe hydronic heating only x x x x x x
2-pipe changeover x x x x x x x x
2-pipe steam only x x x x x x
4-pipe hydronic heating and cooling x x x x x x x
4-pipe changeover x x x x x x x
4-pipe steam/chilled water x x x x x
Electric heat only (single- and two-stage) x x ×
DX/hydronic heating x x x x x
DX/steam heating x x x x x
DX cooling only x x x
Figures Step 7 through Step 17 (pages 20 through 30) show typical wiring diagrams that include
all required and all optional components for typical applications.
Dehumidification
Auto minimum
damper adjust
Face and bypass damper
Valve control
Economizing
Auxiliary (baseboard) heat
Binary inputs
The Tracer ZN521 controller includes four binary inputs. Each binary input associates an input
signal of 0
tool to configure each of the inputs as normally open or normally closed. If an application does not
warrant the use of a particular input, configure the input as Not Used. This will disable the
generation of diagnostics for this function.
Ta bl e 3 gives the function of each binary input.
Vac with open contacts and 24 Vac with closed contacts. You can use the Rover service
Electric heat
Table 3. Binary inputs
Binary input
terminal label
BI1
BI2
CNT-SVX07D-EN 13
Low-coil-temperature detection
Condensate overflow
Function
Input/output functions and wiring for typical applications
Table 3. Binary inputs (continued)
Binary input
terminal label
BI3
BI4
Each function is explained in the following paragraphs. For an explanation of the diagnostics
generated by each binary input, see “Diagnostics,” p. 48. For more information about how the
controller operates, see “Sequence of operations,” p. 31
Occupancy or generic binary input
Fan status
Function
BI1: Low-coil-temperature detection
Note: BI1 applies to hydronic/steam coils only.
The function of low-coil-temperature detection is to protect the coil from freezing. If BI1 is wired
to a binary low-coil-temperature detection device (freeze-protection switch) and a low-coiltemperature condition exists, the Tracer ZN521 will detect the condition and generate a Low Coil
Temp Detection diagnostic.
BI2: Condensate overflow
The function of condensate overflow is to prevent the condensate drain pan from overflowing and
causing water damage to the building. If BI2 is wired to a condensate overflow switch and the level
of condensate reaches the trip point, the Tracer ZN521 will detect the condition and generate a
Condensate Overflow diagnostic.
BI3: Occupancy or generic binary input
The BI3 binary input can function as either:
• The occupancy input
• A generic binary input
The function of occupancy is to save energy by spreading zone setpoints when the zone is
unoccupied. As the occupancy input, BI3 can be used for two related functions. For stand-alone
controllers, BI3 can be hard-wired to a binary switch or timeclock to determine the occupancy
mode—either occupied or unoccupied. For controllers receiving a BAS-communicated occupancy
request, the function of BI3 is to change the mode from occupied to occupied standby. (For more
information on occupancy-related functions, see
BI3 is the only binary input that can be configured as generic. If configured as a generic binary input,
it can be monitored by a BAS and has no direct effect on Tracer ZN521 operation.
BI4: Fan status
The fan status input provides feedback to the controller regarding the fan’s operating status. If BI4
is wired to a fan status switch and the input indicates that the fan is not operating when the
controller has the fan controlled to on, the controller will generate a Low AirFlow—Fan Failure
diagnostic. (For more information, see
Analog inputs
The Tracer ZN521 controller includes seven analog inputs. Ta b l e 4 describes their functions. Each
function is explained in the following paragraphs. For an explanation of the diagnostics generated
“Occupancy modes,” p. 31.)
“Fan status,” p. 41.)
14 CNT-SVX07D-EN
by each analog input, see “Diagnostics,” p. 48. For more information about how the controller
operates, see
Table 4. Analog inputs
Analog input
terminal label
GND: Ground terminals
Use a GND terminal as the common ground for all zone sensor analog inputs.
Input/output functions and wiring for typical applications
“Sequence of operations,” p. 31
ZN
GND
SET
FAN
GND
AI1
AI2
AI3
AI4
Zone temperature
Zone sensor common ground
Local setpoint
Fan mode inpu t
Auxiliary ground
Entering water temperature
Discharge air temperature
Outdoor air temperature or generic temperature
Universal 4–20 mA
Function
ZN: Zone temperature
The ZN analog input functions as the local (hard-wired) zone temperature input. The controller
receives the temperature as a resistance signal from a 10
sensor wired to analog input ZN. A zone temperature value communicated by means of a LonTalk
link can also be used for controllers operating on a BAS. When both a hard-wired and
communicated zone temperature value is present, the controller uses the communicated value. If
neither a hard-wired nor a communicated zone temperature value is present, the controller
generates a Zone Temp Failure diagnostic.
The ZN analog input is also used to communicate timed override requests and cancel requests to
the controller for applications using a Trane zone sensor with
SET: Local setpoint
The SET analog input functions as the local (hard-wired) temperature setpoint input for
applications utilizing a Trane zone sensor with a temperature setpoint thumbwheel. The local
setpoint input is configurable (as enabled or disabled) using the Rover service tool. A setpoint value
communicated by means of a LonTalk link can also be used for controllers operating on a BAS. If
both hard-wired and communicated setpoint values are present, the controller uses the
communicated value. If neither a hard-wired nor a communicated setpoint value is present, the
controller uses the stored default setpoints (configurable using the Rover service tool). If a valid
hard-wired or communicated setpoint value is established and then is no longer present, the
controller generates a Setpoint Failure diagnostic.
FAN: Fan mode input
The FAN analog input functions as the local (hard-wired) fan mode switch input for applications
using the Trane zone sensor with a fan mode switch option. The various fan mode switch positions
(off, low, medium, high, auto) provide different resistances that are interpreted by the Tracer ZN521.
The local fan mode switch input is configurable (as enabled or disabled) using the Rover service
tool. A communicated fan mode request via the LonTalk communications link can also be used for
controllers operating on a BAS. If both hard-wired and communicated fan mode values are present,
the controller uses the communicated value. If neither a hard-wired nor a communicated fan mode
value is present, the controller recognizes the fan mode value as auto and operates according to
kΩ thermistor in a standard Trane zone
ON and CANCEL buttons.
CNT-SVX07D-EN 15
Input/output functions and wiring for typical applications
the default configuration. If a valid hard-wired or communicated fan mode value is established and
then is no longer present, the controller generates a Fan Mode Failure diagnostic.
AI1: Entering water temperature
The AI1 analog input functions as the local (hard-wired) entering water temperature input. An
entering water temperature communicated via the LonTalk communications link can also be used
for controllers operating on a BAS. If both hard-wired and communicated entering water
temperature values are present, the controller uses the communicated value. If a valid hard-wired
or communicated entering water temperature value is established and then is no longer present,
the controller generates an Entering Water Temp Failure diagnostic.
For units configured as 2-pipe or 4-pipe changeover units, the entering water temperature is used
to make heating/cooling operation decisions. If neither a hard-wired nor a communicated entering
water temperature value is present on changeover units, the controller will always operate in
heating mode.
For units not configured as changeover units, the entering water temperature value is used for
information and troubleshooting only and does not affect the operation of the controller.
Note: AI1 is not polarity sensitive; you can connect either terminal to either sensor lead.
AI2: Discharge air temperature
The AI2 analog input functions as the local discharge air temperature input.
Important: The Tracer ZN521 cannot operate without a valid discharge air temperature value.
The controller receives the temperature as a resistance signal from a 10 kΩ thermistor wired to
analog input AI2. The thermistor is typically located downstream from all unit heating and cooling
coils at the unit discharge area.
If a discharge air temperature value is invalid or is not present, the controller generates a Discharge
Air Temp Failure diagnostic and shuts down the equipment. When the thermistor returns to a valid
temperature, the controller automatically allows the equipment to resume normal operation.
Note: AI2 is not polarity sensitive; you can connect either terminal to either sensor lead.
AI3: Outdoor air temperature or generic temperature
The AI3 analog input can function as either:
• An outdoor air temperature input
• A generic temperature input
If AI3 is configured as the local (hard-wired) outdoor air temperature input, the controller receives
the temperature as a resistance signal from a 10
outdoor air temperature value communicated by means of a LonTalk link can also be used for
controllers operating on a BAS. If both hard-wired and communicated outdoor air temperature
values are present, the controller uses the communicated value. If a valid hard-wired or
communicated outdoor air temperature value is established and then is no longer present, the
controller generates an Outdoor Air Temp Failure diagnostic.
Economizing (free cooling) is a function whereby outdoor air is used as a source of cooling before
hydronic or DX cooling is used. The Tracer ZN521 uses the outdoor air temperature value to
determine whether economizing is feasible. Economizing is not possible without a valid outdoor
air temperature. (For more information, see “Economizing (free cooling),” p.
The outdoor air temperature value is also used for the freeze avoidance function. This function is
used for low-coil-temperature protection when the fan is off. The controller enters the freeze
avoidance mode when the outdoor air temperature is below the freeze avoidance setpoint
(configurable using the Rover service tool). (For more information, see
If AI3 is configured as a generic temperature input, it can be monitored by a BAS. The controller
receives the temperature as a resistance signal from a 10
16 CNT-SVX07D-EN
kΩ thermistor wired to analog input AI3. An
38.)
“Freeze avoidance,” p. 41.)
kΩ thermistor wired to analog input AI3.
The generic temperature input can be used with any Trane 10 kΩ thermistor. The thermistor can be
Tracer ZN521
24 Vac
CO
2
sensor
(Trane 5010 0828 shown)
24 Vac
GND
Signal
placed in any location and has no effect on the operation of the controller. The controller will
generate a Generic Temperature Failure diagnostic if the input becomes invalid or goes out of
range.
Note: AI3 is not polarity sensitive; you can connect either terminal to either sensor lead.
AI4: Universal 4–20 mA
The AI4 analog input can be configured in one of the three ways shown in Ta b l e 5.
Table 5. AI4 configuration options and associated measurement ranges
Generic 4–20 mA input 0–100% (4 mA=0%; 20 mA=100%)
CO2 measurement 0–2000 ppm (4 mA=0 ppm; 20 mA=2000 ppm)
Relative humidity (RH) measurement 0–100% (4 mA=0% RH; 20 mA=100% RH)
If this input is not needed for an application, configure it as Not Used. This will disable the
generation of diagnostics.
Note: AI4 is polarity sensitive.
For the generic input configuration, a 4–20 mA sensor must be hard-wired to the AI4 terminal.
(Wiring is dependent on the specific application.) The sensor communicates a value of 0–100% to
the BAS. This configuration has no direct effect on Tracer ZN521 operation. If a valid value is
established and then is no longer present, the controller generates a Generic AIP Failure diagnostic.
For the CO2 measurement configuration, a 4–20 mA sensor must be hard-wired to the AI4 terminal
as shown in
has no direct effect on Tracer ZN521 operation. If a valid value is established and then is no longer
present, the controller generates a CO2 Sensor Failure diagnostic.
Input/output functions and wiring for typical applications
Configuration Measurement range
Figure 5. The sensor will transmit a 0–2000 ppm value to the BAS. This configuration
Figure 5. AI4 terminal wiring: CO2 measurement
For the RH measurement configuration, either a hard-wired 4–20 mA zone humidity sensor (see
Figure 2) must provide a value to the controller or a BAS communicates a value to the controller.
The controller uses this value to support the dehumidification function. (For more information, see
“Dehumidification,” p. 40.) If a valid hard-wired or communicated relative humidity value is
established and then is no longer present, the controller generates a Humidity Input Failure
diagnostic and disables the dehumidification function.
CNT-SVX07D-EN 17
Input/output functions and wiring for typical applications
Tracer ZN521
RH sensor
Figure 6. AI4 terminal wiring: RH measurement
Binary outputs
The ZN521 zone controller supports fan coil, blower coil, and unit ventilator applications that may
include the following components:
• Supply fan with up to three speeds
• Hydronic cooling and/or heating coils with two-position or tri-state modulating control valve
• DX cooling (single stage)
• Electric heat (single stage or two stage)
• Baseboard heat (single stage)
• Tri-state modulating outdoor/return air damper
• Tri-state modulating face-and-bypass damper
The Tracer ZN521 controller includes ten binary outputs. Each binary output is a triac with a rating
of 12 VA at 24 Vac. Ta bl e 6 describes the function of each output.
Table 6. Binary output functions
Binary output Functions
• Fan high
• Fan medium
• Exhaust fan or damper
• Fan low
• Modulating cooling/changeover valve, open
• Two-position cooling/changeover valve
• DX cooling
• Modulating cooling/changeover valve, close
• Face-and-bypass damper, open to face
• Modulating heating valve, open
• Two-position heating valve
• Electric heat, stage 1
• Modulating heating valve, close
• Face-and-bypass damper, close (bypass)
• Electric heat, stage 2
• Outdoor air damper, open (return air da mper, close)
• Outdoor air damper, close (return air damper, open )
• Baseboard heat
• Generic
1
2
3
4
5
6
7
8
9
10
18 CNT-SVX07D-EN
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