Trane Tracer ZN521 Installation And Operation Manual

Page 1

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

Page 2

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)

Page 3

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

CNT-SVX07D-EN 3

Page 4

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

Page 5

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

Page 6

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

Page 7

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)

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

Page 8

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.

Page 9

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

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

Page 10

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

Page 11

General wiring information

24 Vac transformer

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

Page 12

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

Page 13

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

Page 14

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

Page 15

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

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

Page 16

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.

Page 17

The generic temperature input can be used with any Trane 10 kΩ thermistor. The thermistor can be

Tracer ZN521

24 Vac

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

Page 18

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

18 CNT-SVX07D-EN

Page 19

Input/output functions and wiring for typical applications

Generic binary output

Binary output 10 is the only output that can be configured as a generic binary output. When configured as a generic binary output, it can be controlled only by a BAS, and has no direct effect on Tracer ZN521 operation.

Overriding binary outputs

The Tracer ZN521 controller includes a manual output test and a water valve override feature. Use the manual output test to manually control the outputs in a defined sequence. For information, see

“Manual output test,” p. 43.

The water valve override feature is a procedure used for water balancing. Using the Rover service tool or a BAS, a user can specify that a Tracer ZN521 override the state of water valves to:

• Open all valves

• Close all valves

The controller resets itself to normal operation after two hours.

Wiring requirements and options

Ta bl e 7 shows required controller inputs for minimal proper operation of all applications.

Table 7. Required controller inputs for proper operation

Function Input source

24 Vac power Terminals: GND, 24 V “AC power wiring,” p. 10

Zone temperature

Discharge air temperature Terminals: AI2

Entering water temperature— required only for units with auto changeover

Outdoor air temperature— required only for economizing

Relative humidity—required only for dehumidification

Terminals: ZN, GND or communicated

Terminal: AI1 or communicated

Terminals: AI3 or communicated

Terminals: AI4

For more information,

see:

“ZN: Zone temperature,” p. 15

“AI2: Discharge air temperature,” p. 16

“AI1: Entering water temperature,” p. 16

“AI3: Outdoor air temperature or generic temperature,” p. 16

“AI4: Universal 4–20 mA,” p.

Figure 7, p . 20 through Figure 17, p. 30 show typical applications that include all required and all

optional components.

CNT-SVX07D-EN 19

Page 20

Input/output functions and wiring for typical applications

LonTalk

Entering water temperature

Outdoor air or generic temperature

24 V

†

Exhaust (or fan, medium speed)

24 V

†

Fan, low speed

24 V

†

Cooling valve

24 V

†

Fan, high speed

Low-coil-temperature detection (closed=normal)*

Condensate overflow (closed=normal)*

Occupancy (open=occupied)*

LonTalk

H N

24 Vac

24 V

†

Generic/baseboard heat

24 V

†

Electric heat, stage 1 (optional)

out

Fan status (closed=on)*

24 V

†

Electric heat, stage 2 (optional)

24 V

†

Outdoor air damper actuator

AI4 input: See Figures Step 5 and Step 6 on

p. 18 for wiring

options

Discharge air temperature

Open

* All binary inputs are configurable.

†

Connect 24 V to an AC POWER (24V) terminal.

Figure 7. Two-pipe hydronic-cooling unit

20 CNT-SVX07D-EN

Page 21

Figure 8. Two-pipe hydronic-heating unit

Entering water temperature

Outdoor air or generic temperature

24 V

†

Exhaust (or fan, medium speed)

24 V

†

Fan, low speed

24 V

†

Fan, high speed

Condensate overflow (closed=normal)*

Occupancy (open=occupied)*

LonTalk

H N

24 Vac

24 V

†

Generic/baseboard heat

24 V

†

Heating valve

out

Fan status (closed=on)*

24 V

†

Outdoor air damper actuator

Discharge air temperature

Open

Low-coil-temperature detection (closed=normal)*

LonTalk

* All binary inputs are configurable.

†

Connect 24 V to an AC POWER (24V) terminal.

AI4 input: See Figures Step 5 and Step 6 on

p. 18 for wiring

options

Input/output functions and wiring for typical applications

CNT-SVX07D-EN 21

Page 22

Input/output functions and wiring for typical applications

LonTalk

Entering water temperature

Outdoor air or generic temperature

24 V

†

Exhaust (or fan, medium speed)

24 V

†

Fan, low speed

24 V

†

Fan, high speed

Low-coil-temperature detection (closed=normal)*

Condensate overflow (closed=normal)*

Occupancy (open=occupied)*

LonTalk

H N

24 Vac

24 V

†

Generic/baseboard heat

24 V

†

Heating/cooling changeover valve

* All binary inputs are configurable.

†

Connect 24 V to an AC POWER (24V) terminal.

Fan status (closed=on)

24 V

†

Outdoor air damper actuator

Discharge air temperature

24 V

†

Electric heat, stage 1 (optional)

24 V

†

Electric heat, stage 2 (optional)

Open

out

AI4 input: See

Figures Step 5

and Step 6 on

p. 18 for wiring

options

Figure 9. Two-pipe hydronic heating/cooling unit with auto changeover

22 CNT-SVX07D-EN

Page 23

LonTalk

Entering water temperature

Outdoor air or generic temperature

24 V

†

Exhaust (or fan, medium speed)

24 V

†

Fan, low speed

24 V

†

Fan, high speed

Low-coil-temperature detection

(open=normal)*

Condensate overflow (closed=normal)*

Occupancy (open=occupied)*

LonTalk

H N

24 Vac

24 V

†

Generic/baseboard heat

24 V

†

Cooling valve

out

Fan status (closed=on)*

24 V

†

Outdoor air damper actuator

Discharge air temperature

24 V

†

Heating valve

Open

* All binary inputs are configurable.

†

Connect 24 V to an AC POWER (24V) terminal.

AI4 input: See Figures Step 5 and Step 6 on

p. 18 for wiring

options

Input/output functions and wiring for typical applications

Figure 10. Four-pipe hydronic heating/cooling unit

CNT-SVX07D-EN 23

Page 24

Input/output functions and wiring for typical applications

LonTalk

Outdoor air or generic temperature

24 V

†

Exhaust (or fan, medium speed)

24 V

†

Fan, low speed

24 V

†

Fan, high speed

Low-coil-temperature detection (closed=normal)*

Condensate overflow (closed=normal)*

Occupancy (open=occupied)*

LonTalk

H N

24 Vac

24 V

†

Generic/baseboard heat

24 V

†

Heating/cooling changeover valve

out

Fan status (closed=on)*

24 V

†

Outdoor air damper actuator

Discharge air temperature

24 V

†

Auxiliary heating valve

Open

Entering water temperature

Open

* All binary inputs are configurable.

†

Connect 24 V to an AC POWER (24V) terminal.

AI4 input: See Figures Step 5

and Step 6 on

p. 18 for wiring

options

Figure 11. Four-pipe heating/cooling unit with auto changeover

24 CNT-SVX07D-EN

Page 25

Figure 12. Two-pipe heating unit with DX cooling

LED

A BBA

AI4+20 GND

AI2 AI3FAN GND AI1

GND

LED

SET

ZONE SENSOR

SERVICE

ANALOG INPUTS COMM5

COMM5

AC POWER

24V24V

GND

24V

BINARY INPUTS

BI3BI1 BI2 BI4

BINARY OUTPUTS

21 43 765 8 9

LED

STATUS10

Cancel

}

LonTalk

Entering water temperature

Outdoor air or generic temperature

24 V

†

Exhaust (or fan, medium speed)

24 V

†

Fan, low speed

24 V

†

Fan, high speed

Low-coil-temperature detection (closed=normal)*

Condensate overflow (closed=normal)*

Occupancy (open=occupied)*

LonTalk

H N

24 Vac

24 V

†

Generic/baseboard heat

24 V

†

DX cooling

out

Fan status (closed=on)*

24 V

†

Outdoor air damper actuator

Discharge air temperature

24 V

†

Heating valve

Open

* All binary inputs are configurable.

†

Connect 24 V to an AC POWER (24V) terminal.

AI4 input: See

Figures Step 5

and Step 6 on

p. 18 for wiring

options

Input/output functions and wiring for typical applications

CNT-SVX07D-EN 25

Page 26

Input/output functions and wiring for typical applications

LED

A BBA

AI4+20 GND

AI2 AI3FAN GND AI1

GND

LED

SET

ZONE SENSOR

SERVICE

ANALOG INPUTS COMM5

COMM5

AC POWER

24V24V

GND

24V

BINARY INPUTS

BI3BI1 BI2 BI4

BINARY OUTPUTS

21 43 765 8 9

LED

STATUS10

Cancel

}

LonTalk

Entering water temperature

Outdoor air or generic temperature

24 V

†

Exhaust

24 V

†

Fan, high speed

Low-coil-temperature detection (closed=normal)*

Condensate overflow (closed=normal)*

Occupancy (open=occupied)*

LonTalk

H N

24 Vac

24 V

†

Generic/baseboard heat

24 V

†

DX cooling

out

Fan status (closed=on)*

24 V

†

Outdoor air damper actuator

Discharge air temperature

24 V

†

Electric heat, stage 2 (optional)

Open

24 V

†

Electric heat, stage 1 (optional)

AI4 input: See

Figures Step 5

and Step 6 on

p. 18 for wiring

options

* All binary inputs are configurable.

†

Connect 24 V to an AC POWER (24V) terminal.

Figure 13. Electric heat unit with DX cooling

26 CNT-SVX07D-EN

Page 27

Figure 14. Electric heat unit

LonTalk

Entering water temperature

Outdoor air or generic temperature

24 V

†

Exhaust

24 V

†

Fan, high speed

Low-coil-temperature detection (closed=normal)*

Condensate overflow (closed=normal)*

Occupancy (open=occupied)*

LonTalk

H N

24 Vac

24 V

†

Generic/baseboard heat

24 V

†

Electric heat, stage 1

out

Fan status (closed=on)*

24 V

†

Outdoor air damper actuator

Discharge air temperature

24 V

†

Electric heat, stage 2

Open

* All binary inputs are configurable.

†

Connect 24 V to an AC POWER (24V) terminal.

AI4 input: See

Figures Step 5

and Step 6 on

p. 18 for wiring

options

Input/output functions and wiring for typical applications

CNT-SVX07D-EN 27

Page 28

Input/output functions and wiring for typical applications

LonTalk

Entering water temperature

Outdoor air or generic temperature

24 V

†

Exhaust (or fan, medium speed)

24 V

†

Fan, low speed

24 V

†

Fan, high speed

Low-coil-temperature detection (closed=normal)*

Condensate overflow (closed=normal)*

Occupancy (open=occupied)*

LonTalk

H N

24 Vac

24 V

†

Generic/baseboard heat

out

Fan status (closed=on)*

24 V

†

Outdoor air damper actuator

Discharge air temperature

24 V

†

Face & bypass damper actuator

Open

24 V

†

Heat isolation valve, open/close

* All binary inputs are configurable.

†

Connect 24 V to an AC POWER (24V) terminal.

AI4 input: See

Figures Step 5

and Step 6 on

p. 18 for wiring

options

Figure 15. Two-pipe heating unit with face-and-bypass damper

28 CNT-SVX07D-EN

Page 29

LonTalk

Entering water temperature

Outdoor air or generic temperature

24 V

†

Exhaust (or fan, medium speed)

24 V

†

Fan, low speed

24 V

†

Fan, high speed

Low-coil-temperature detection (closed=normal)*

Condensate overflow (closed=normal)*

Occupancy (open=occupied)*

LonTalk

H N

24 Vac

24 V

†

Generic/baseboard heat

24 V

†

Heating/cooling isolation valve, open/close

out

Fan status (closed=on)*

24 V

†

Outdoor air damper actuator

Discharge air temperature

24 V

†

Face-and-bypass damper actuator

Open

* All binary inputs are configurable.

†

Connect 24 V to an AC POWER (24V) terminal.

AI4 input: See

Figures Step 5

and Step 6 on

p. 18 for wiring

options

Input/output functions and wiring for typical applications

Figure 16. Two-pipe heating/cooling unit with face-and-bypass damper

CNT-SVX07D-EN 29

Page 30

Input/output functions and wiring for typical applications

LonTalk

Entering water temperature

Outdoor air or generic temperature

24 V

†

Exhaust (or fan, medium speed)

24 V

†

Fan, low speed

24 V

†

Fan, high speed

Low-coil-temperature detection (closed=normal)*

Condensate overflow (closed=normal)*

Occupancy (open=occupied)*

LonTalk

H N

24 Vac

24 V

†

Generic/baseboard heat

24 V

†

Face and bypass damper actuator

out

Fan status (closed=on)*

24 V

†

Outdoor air damper actuator

Discharge air temperature

24 V

†

Heating isolation valve, open/close

Open

24 V

†

Cooling isolation valve, open/close

* All binary inputs are configurable.

†

Connect 24 V to an AC POWER (24V) terminal.

AI4 input: See

Figures Step 5

and Step 6 on

p. 18 for wiring

options

Figure 17. Four-pipe heating/cooling unit with face-and-bypass damper

30 CNT-SVX07D-EN

Page 31

Sequence of operations

The Tracer ZN521 zone controller will operate to maintain the zone temperature setpoint. This chapter discusses many of the operational sequences used by the controller to accomplish this goal.

Power-up sequence

When 24 Vac power is initially applied to the Tracer ZN521 zone controller, the following sequence occurs:

1. The green status indicator LED turns on (see “Interpreting LEDs,” p. 47).

2. All outputs are controlled off. All modulating valves and dampers close, and the face-andbypass damper calibrates to bypass (when present).

3. The controller reads all input local values to determine initial values.

4. The random-start timer begins (see “Random start,” p. 31).

5. If a hard-wired zone-temperature value is not detected, the controller begins to wait for a communicated value. (This can take several minutes [15-minute default] and occurs concurrently with the remainder of the power-up sequence.)

6. The random-start timer expires.

7. The power-up control wait function begins automatically if the configured power-up control wait time is greater than 0 seconds. When this function is enabled, the controller waits for the configured amount of time (from 0 to 120 seconds) to allow a communicated occupancy request to arrive. If a communicated occupancy request arrives, normal operation can begin. If a communicated occupancy request does not arrive, the controller assumes stand-alone operation.

8. Normal operation begins assuming no diagnostics have been generated.

Random start

Random start is intended to prevent all units in a building from energizing at the same time. The random-start timer delays the fan and any heating or cooling start-up from 5 to 30 seconds. If neither heating nor cooling is initiated, or if fan operation is not required during the delay, the random-start timer will time-out.

Occupancy modes

Occupancy modes can be controlled by any of the following:

• The state of the local (hard-wired) occupancy binary input BI3 (see “BI3: Occupancy or generic

binary input,” p. 14)

• A timed override request from a Trane zone sensor (see “Timed override control,” p. 32)

• A communicated signal from a peer device (see “Peer-to-peer communication,” p. 40)

• A communicated signal from a BAS

A communicated request, either from a BAS or a peer controller, takes precedence over local requests. If a communicated occupancy request has been established and is no longer present, the controller reverts to the default (occupied) occupancy mode after 15 minutes (if no hard-wired occupancy request exists). The Tracer ZN521 has the following occupancy mode options:

• Occupied

• Unoccupied

• Occupied standby

• Occupied bypass

CNT-SVX07D-EN 31

Page 32

Sequence of operations

Occupied mode

In occupied mode, the controller maintains the zone temperature based on the occupied heating or cooling setpoints. The controller uses the occupied mode as a default mode when other forms of occupancy request are not present. The fan will run continuously. The outdoor air damper will close when the fan is off. The temperature setpoints can be local (hard-wired), communicated, or stored default values (configurable using the Rover service tool).

Unoccupied mode

In unoccupied mode, the controller attempts to maintain the zone temperature based on the unoccupied heating or cooling setpoint. The fan will cycle between high speed and off. The outdoor air damper will remain closed, unless economizing. The controller always uses the stored default setpoint values (configurable using the Rover service tool), regardless of the presence of a hardwired or communicated setpoint value.

Occupied standby mode

The controller is placed in occupied standby mode only when a communicated occupied request is combined with an unoccupied request from occupancy binary input BI3. In occupied standby mode, the controller maintains the zone temperature based on the occupied standby heating or cooling setpoints. Because the occupied standby setpoints are typically spread 2°F (1.1°C) in either direction and the outdoor air damper is closed, this mode reduces the demand for heating and cooling the space. The fan will run as configured (continuous or cycling) for occupied mode. The controller always uses the stored default setpoint values (configurable using the Rover service tool), regardless of hard-wired or communicated setpoint values. In addition, the outdoor air damper uses the Economizer Occupied Standby Minimum Position setpoint to reduce the ventilation rate.

Occupied bypass mode

The controller is placed in occupied bypass mode when the controller is operating in the unoccupied mode and either the timed override ON button on the Trane zone sensor is pressed or the controller receives a communicated occupied bypass signal from a BAS. In occupied bypass mode, the controller maintains the zone temperature based on the occupied heating or cooling setpoints. The fan will run as configured (continuous or cycling). The outdoor air damper will close when the fan is off. The controller will remain in occupied bypass mode until either the button is pressed on the Trane zone sensor or the occupied bypass time (configurable using the Rover service tool) expires. The temperature setpoints can be local (hard-wired), communicated, or stored default values (also configurable using the Rover service tool).

Timed override control

If the zone sensor has a timed override option (ON/CANCEL buttons), pushing the ON button initiates a timed override on request. A timed override on request changes the occupancy mode from unoccupied mode to occupied bypass mode. In occupied bypass mode, the controller controls the zone temperature based on the occupied heating or cooling setpoints. The occupied bypass time, which resides in the Tracer ZN521 and defines the duration of the override, is configurable from 0 to 240 minutes (default value of 120 minutes). When the occupied bypass time expires, the unit transitions from occupied bypass mode to unoccupied mode. Pushing the the timed override request. A timed override cancel request will end the timed override before the occupied bypass time has expired and will transition the unit from occupied bypass mode to unoccupied mode.

If the controller is in any mode other than unoccupied when the ON button is pressed, the controller still starts the occupied bypass timer without changing the mode to occupied bypass. If the controller is placed in unoccupied mode before the occupied bypass timer expires, the controller

CANCEL

CANCEL button cancels

32 CNT-SVX07D-EN

Page 33

will be placed in occupied bypass mode and remain in that mode until either the CANCEL button is

Active zone temperature setpoint

Diffe rence

Calculated discharge air temperature setpoint

Calculated unit heating/cooling capacity

Measured

zone

temperature

Measured discharge air temperature

Difference

pressed on the Trane zone sensor or the occupied bypass time expires.

Zone temperature control

The Tracer ZN521 zone controller uses two methods of zone temperature control:

• Cascade zone control—used in the occupied, occupied bypass, and occupied standby modes

• Simplified zone control—used in the unoccupied mode

Cascade zone control

Cascade zone control maintains zone temperature by controlling the discharge air temperature to control the zone temperature. The controller uses the difference between the measured zone temperature and the active zone temperature setpoint to produce a discharge air temperature setpoint. The controller compares the discharge air temperature setpoint with the discharge air temperature and calculates a unit heating/cooling capacity accordingly (see devices (outdoor air damper, valves, etc.) operate in sequence based on the unit heating/cooling capacity (0–100%).

Figure 18. Cascade zone control

Sequence of operations

Figure 1). The end

If the discharge air temperature falls below the Discharge Air Control Point Low Limit (configurable using the Rover service tool) and cooling capacity is at a minimum, available heating capacity will be used to raise the discharge air temperature to the low limit (see

p. 33).

“Discharge air tempering,”

Simplified zone control

In the unoccupied mode, the controller maintains the zone temperature by calculating the required heating or cooling capacity (0–100%) according to the measured zone temperature and the active zone temperature setpoint. The active zone temperature setpoint is determined by the current operating modes, which include occupancy and heat/cool modes.

Discharge air tempering

If the controller is in cooling mode, cascade zone control initiates a discharge air tempering function when the discharge air temperature falls below the Discharge Air Control Point Low Limit (configurable using the Rover service tool) and all cooling capacity is at a minimum. The discharge air tempering function allows the controller to provide heating capacity (if available) to raise the discharge air temperature to the Discharge Air Control Point Low Limit.

The discharge air tempering function is often initiated under the following circumstances: Cold outdoor air is brought in through the outdoor air damper when the damper is at (a high) minimum

CNT-SVX07D-EN 33

Page 34

Sequence of operations

position, causing the discharge air temperature to fall below the Discharge Air Control Point Low Limit.

Morning warm-up

Morning warm-up can occur any time the controller is in the occupied mode. The controller supply fan always runs in the occupied mode.

Morning warm-up is initiated when the zone temperature is more than 2°F (1.1°C) below the occupied heating setpoint. Morning warm-up is terminated when the zone temperature is less than 2°F (1.1°C) below the occupied heating setpoint.

When morning warm-up is terminated, the ZN520 runs in occupied heat mode. The outdoor air damper will be closed when the zone temperature is 3°F (1.7°C) or more below the occupied heating setpoint. The outdoor air damper will be at the minimum position when the zone temperature is 2°F (1.1°C) or less below the occupied heating setpoint. The outdoor air damper modulates between the minimum position and closed as the zone temperature goes from 2°F (1.1°C) below the occupied heating setpoint to 3°F (1.7°C) below the occupied heating setpoint.

Morning cool-down

Morning cool-down is initiated when the controller transitions from unoccupied to occupied and the zone temperature is 3°F (1.7°C) above the occupied cooling setpoint. The fan will turn on and the outdoor air damper will remain closed. The damper modulates between closed and the minimum position as the zone temperature cools down toward the occupied cooling setpoint.

The damper will be closed when the zone temperature is more than 3°F (1.7°C) above the occupied cooling setpoint. The damper will be at the minimum position when the zone temperature is less than 2°F (1.1°C) above the occupied cooling setpoint. If economizing is possible, the damper will open up above the minimum position. Cool down can only happen once.

When the outdoor air damper gets to its minimum position, morning cool-down is over and cannot happen again until the next transition from unoccupied to occupied.

The controller will be in the occupied cooling mode when morning cool-down is over.

Heating or cooling mode

The heating or cooling mode can be determined in one of two ways:

• By a communicated signal from a BAS or a peer controller

• Automatically, as determined by the controller

A communicated heating signal permits the controller to heat only. A communicated cooling signal permits the controller to cool only. A communicated auto signal allows the controller to automatically change from heating to cooling and vice versa.

In heating and cooling mode, the controller maintains the zone temperature based on the active heating setpoint and the active cooling setpoint, respectively. The active heating and cooling setpoints are determined by the occupancy mode of the controller.

For two-pipe and four-pipe changeover units, normal heat/cool operation will not begin until the ability to conduct the desired heating or cooling operation is verified. This is done using the entering water temperature sampling function, for which a valid entering water temperature is required. When neither a hard-wired nor a communicated entering water temperature value is present on changeover units, the controller will operate in heating mode only and assume the coil water is hot. The sampling function is not used.

The entering water temperature sampling function is used only for changeover applications. It is used for information and troubleshooting only and does not affect the operation of the controller. (For more information, see

34 CNT-SVX07D-EN

“Entering water temperature sampling function,” p. 35.)

Page 35

Entering water temperature sampling function

The entering water temperature sampling function is used with two-pipe and four-pipe changeover units and requires a valid entering water temperature value. If the entering water temperature value is less than 5°F (2.8°C) above a valid zone temperature value for hydronic heating and greater than 5°F (2.8°C) below a valid zone temperature value for hydronic cooling, the sampling function is enabled. When the sampling function is enabled, the controller opens the main hydronic valve to allow the water temperature to stabilize. After 3 minutes, the controller again compares the entering water temperature value to the zone temperature value to determine if the desired heating or cooling function can be accomplished. If the entering water temperature value remains out of range to accomplish the desired heating/cooling function, the controller closes the main hydronic valve and waits 60 minutes to attempt another sampling. If the entering water temperature value falls within the required range, it resumes normal heating/cooling operation and disables the sampling function.

Fan operation

The Tracer ZN521 supports up to three fan speeds. Every time the fan is enabled, the fan will begin operation and run on high speed for a period of time (0.5 seconds for fan coils and 3 seconds for unit ventilators and blower coils) before changing to any other speed. This is done to provide adequate torque to start the fan motor from the off position. The fan will always operate continuously while either heating or cooling during occupied, occupied standby, and occupied bypass operation. During unoccupied operation, the fan will cycle between off and high regardless of the fan configuration. The controller can be configured to auto, to a specific fan speed, or to off. If both a communicated and hard-wired value (fan-speed switch) is present, the communicated value has priority.

Note: In occupied mode, The Tracer ZN521 zone controller requires continuous fan operation

because of cascade zone control. In unoccupied mode, the fan cycles.

When the controller receives a communicated auto signal (or the associated fan-speed switch is

AUTO with no communicated value present), the fan will operate in the auto mode. In the auto

set to mode, the fan will operate according to the fan default (configurable using the Rover service tool). The fan speed can be configured to default to auto, a specific speed, or off for both heating and cooling operation.

Configured as auto and with multiple speeds available, the fan will automatically switch speeds depending on the difference between the zone temperature and the active zone temperature setpoint. The fan speed will increase as the difference increases and decrease as the difference decreases.

When the controller receives a communicated fan-speed signal (high, medium, low) or the associated fan-speed switch is set to a specific fan speed, the fan will run continuously at the desired fan speed during occupied, occupied standby, and occupied bypass operation. During unoccupied operation, the fan will cycle between off and high regardless of the communicated fanspeed signal or fan-speed switch setting (unless either of these is off, which will control the fan off).

The fan will turn off when the controller receives a communicated off signal, when the fan-speed switch is set to to off and the fan is operating in the auto mode.

The ability to enable or disable the controller’s associated fan speed switch is configurable.

OFF, when specific diagnostics are generated, or when the default fan speed is set

Sequence of operations

Exhaust control

Exhaust control is accomplished by a single-speed exhaust fan or a two-position exhaust damper. BOP2 controls this function. To enable exhaust control, configure the controller by selecting Exhaust Fan/Damper Present and by selecting the number of fan speeds as either One or Tw o.

The exhaust function is coordinated with the supply fan and outdoor/return air dampers as follows:

CNT-SVX07D-EN 35

Page 36

Sequence of operations

• The exhaust output is energized only when the supply fan is operating and the outdoor air damper position (%) is greater than or equal to the Exhaust Fan/Damper Enable Setpoint (configurable using the Rover service tool).

• The exhaust output is de-energized if the outdoor air damper position drops 10% below the Exhaust Fan/Damper Enable Setpoint.

• If the Exhaust Fan/Damper Enable Setpoint is less than 10%, the exhaust output is energized if the outdoor air damper position is at the setpoint and de-energized at 0.

Valve operation

The Tracer ZN521 zone controller supports one or two tri-state modulating or two-position valves, depending on the application (see Tab l e 8). The controller opens and closes the appropriate valve(s) to maintain the active zone temperature setpoint at the heating setpoint in heating mode or the cooling setpoint in cooling mode (see “Cascade zone control,” p. 33). For face-and-bypass applications, one or two isolation valves are controlled.

Table 8. Valve control options

Application

Hydronic/steam fan coils and blower coils Unit ventilators with valve control Face-and-bypass unit ventilators

Tri-state

modulating

× ×

Two-position

Isolation

(two-position)

Modulating valve operation

The Tracer ZN521 supports tri-state modulating valve control. Two binary outputs control each valve: one to drive the valve open and one to drive the valve closed. The stroke time for each valve is configurable using the Rover service tool. The controller supports heating, cooling, or heat/cool changeover with a single valve/coil for two-pipe applications. The controller supports cooling or heat/cool changeover with the main valve/coil and heating only with the auxiliary valve/coil for four-pipe applications. The controller moves the modulating valve to the desired positions based on heating or cooling requirements.

Modulating valve calibration

Calibration of modulating valves is done automatically. During normal operation, the controller overdrives the actuator (135% of the stroke time) whenever a position of 0% or 100% is requested. as part of Tracer ZN521 normal operation. At power-up or after a power outage, the controller first drives all modulating valves (and dampers) to the closed position. The controller calibrates to the fully closed position by overdriving the actuator (135% of the stroke time). Then, the controller resumes normal operation.

Two-position valve operation

The Tracer ZN521 supports two-position valves with a single binary output for each valve. Controllers used for two-pipe applications support heating, cooling, or heat/cool changeover with a single valve/coil. Controller used for four-pipe applications support cooling or heat/cool changeover with a main valve/coil, and heating only with an auxiliary valve/coil.

Isolation-valve operation

See “Face-and-bypass damper operation,” p. 39.

36 CNT-SVX07D-EN

Page 37

Two-pipe operation

For two-pipe applications, the Tracer ZN521 can be configured as heating only, cooling only, or heat/cool changeover. The coil can be used as the primary heating source and/or the primary cooling source. If present, an electric heating element can be used only as the primary heating source (instead of hydronic or steam heating). A changeover unit requires a valid entering water temperature value—either communicated or hard-wired—to operate properly (see

water temperature,” p. 16 and “Entering water temperature sampling function,” p. 35).

Four-pipe operation

For four-pipe applications, the Tracer ZN521 can be configured as heat/cool or heat/cool changeover. The main coil can be used as the primary cooling source or the primary heating/ cooling source. The auxiliary coil can be used only as the primary heating source, not as a second stage of heating. During normal operation, the controller never uses the main coil and auxiliary coil simultaneously. A changeover unit requires a valid entering water temperature value—either communicated or hard-wired—to operate properly (see and “Entering water temperature sampling function,” p. 35). Electric heat control is not available on four-pipe applications.

Modulating outdoor/return air dampers

The Tracer ZN521 operates the modulating outdoor/return air dampers according to the following factors:

• Occupancy mode

• Outdoor air temperature (communicated or hard-wired sensor)

• Zone temperature

•Setpoint

• Discharge air temperature

• Discharge air temperature setpoint

The minimum position for an outdoor air damper is configurable using the Rover service tool for occupied and occupied standby modes and for low-speed fan operation. A controller can also receive a BAS-communicated outdoor air damper minimum position.

A BAS-communicated minimum position setpoint has priority over all locally configured setpoints. When a communicated minimum position setpoint is not present, the controller uses the configured minimum position for low fan speed whenever the fan is running at low speed, regardless of the occupancy state. See controller determines the position of the modulating outdoor air damper.

Ta bl e 9 and Tab l e 10 for more information about how the

Sequence of operations

“AI1: Entering

“AI1: Entering water temperature,” p. 16

Table 9. Modulating outdoor air damper position setpoint determination

BAS-communicated

Occupancy

Unoccupied Any value Any value 0% (closed) Occupied

Occupied bypass Occupied standby

Occupied Occupied bypass Occupied standby

Occupied Occupied bypass

Occupied standby Invalid Medium/high Occupied standby minimum

CNT-SVX07D-EN 37

setpoint

Valid Any value BAS-communicated

Invalid Low Occupied low fan minimum

Invalid Medium/high Occupied minimum

Fan speed Active minimum setpoint

Page 38

Sequence of operations

Table 10. Relationship between outdoor temperature sensors and damper position

Modulating outdoor air damper position

Occupied or occupied

Outdoor air temperature

No or invalid outdoor air temperature

Failed outdoor air sensor

Outdoor air temperature presen t and economizing possible

Outdoor air temperature presen t and economizing not possible

For an explanation of the economizing feature, see “Economizing (free cooling),” p. 38.

Open to occupied minimum position

Economizing; damper controlled between occupied minimum position and 100%

Open to occupied minimum

position

bypass

Occupied standby Unoccupied

Open to occupied standby minimum position

Economizing; damper controlled between occupied standby minimum position and 100%

Open to occupied standby minimum position

ASHRAE Cycle 1 conformance

Tracer ZN521 applications with an outside air damper support ASHRAE Cycle 1 conformance. ASHRAE Cycle 1 operation admits 100% outdoor air at all times except during a warm-up cycle. A tri-state modulating damper actuator is required for this operation. For Tracer ZN521 ASHRAE Cycle 1 conformance, configure the minimum position of the economizer setpoint to 100% open during occupied periods. If the zone temperature drops 3°F (1.7°C) below the active zone temperature setpoint, the Tracer ZN521 closes the outdoor air damper regardless of the minimum position setpoint.

Closed

Open and economizing during unit operation; otherwise closed

Closed

ASHRAE Cycle 2 conformance

Tracer ZN521 controller applications with modulating outside air damper support ASHRAE Cycle 2 conformance. ASHRAE Cycle 2 operation allows the modulating outdoor air damper to completely close when the zone temperature drops 3°F (1.7°C) or more below the active zone temperature setpoint. If the zone temperature rises to within 2°F (1.2°C) of the active setpoint, the damper opens to the occupied or occupied standby minimum damper positions. If the zone temperature is between 2°F and 3°F (1.2°C and 1.7°C) below the active zone temperature setpoint, the damper modulates between the minimum position and closed.

If the discharge air temperature is between the discharge air temperature low limit and the discharge air temperature low setpoint, the damper modulates between the minimum position and closed. If this situation is concurrent with ASHRAE Cycle 2 operation, the lesser of the two setpoints will determine the actual damper position.

Economizing (free cooling)

Cooling with outdoor air, when the temperature is low enough to make this possible, is referred to as economizing or free cooling. Tracer ZN521 controller applications with modulating outside air damper support economizing. The modulating outdoor air damper provides the first source of cooling for the Tracer ZN521. The controller initiates economizing if the outdoor air temperature is below the economizer enable point (configurable using the Rover service tool). If economizing is initiated, the controller modulates the outdoor air damper (between the active minimum damper position and 100%) to control the amount of outdoor air cooling capacity. When the outdoor air temperature rises 5°F (2.8°C) above the economizer enable point, the controller disables economizing and moves the outdoor air damper back to its predetermined minimum position based on the current occupancy mode or communicated minimum outdoor air damper position. If an outdoor air temperature value is not present, economizing is disabled.

38 CNT-SVX07D-EN

Page 39

Sequence of operations

Two-position control of a modulating outdoor air damper

The Tracer ZN521 does not support a two-position outdoor air damper actuator. However, a modulating outdoor/return air damper actuator can be used for two-position control. Two-position control can be accomplished by not providing an outdoor air temperature (neither hard-wired nor communicated) to the controller, and by setting the damper minimum position (using the Rover service tool) to the desired value (typically, 100%).

Face-and-bypass damper operation

The Tracer ZN521 can control a face-and-bypass damper to modulate a percentage of air to the face of the coil(s) and around (bypass) the coil(s) to maintain zone comfort. For two-pipe changeover applications, if the controller requests heating and hot water is available, the face-and-bypass damper modulates to the face position. If the controller requests heating and hot water is not available, the face-and-bypass damper remains in the bypass position, and water sampling may be initiated (see applications, both heat and cool capacity are assumed to be available.

Face-and-bypass, isolation-valve operation

A Tracer ZN521 with a face-and-bypass damper controls on/off isolation valve(s) to prevent unwanted water flow through the coil(s) when no airflow is passing over the coil (100% bypass). In two-pipe applications, the isolation valve stops water flow, preventing radiant heat (heating mode) and excessive condensate (cooling mode) from the coil. In four-pipe applications, the isolation valves are used to prevent simultaneous heating and cooling.

The heating or cooling isolation valve opens whenever capacity is requested (>0%) as the face-andbypass damper begins to modulate toward the coil face. The isolation valve closes when capacity returns to 0%.

“Entering water temperature sampling function,” p. 35). For four-pipe changeover

DX cooling operation

The Tracer ZN521 supports one stage of direct expansion (DX) compressor operation for cooling only.

Note: The controller does not use the DX compressor and economizing simultaneously. Not doing

so prevents short cycling from occurring if the entering air temperature is too low for the evaporator coil to operate as designed.

Electric heat operation

The Tracer ZN521 supports both single-stage and two-stage electric heat. Electric heat is cycled on and off to maintain the discharge air temperature at the active heating setpoint. Two-pipe changeover units with electric heat use the electric heat only when hot water is not available. The use of both electric and hydronic heat is not supported.

Baseboard heat operation

When configured for baseboard heat output, the controller turns on baseboard heat at 2.2°F (1.2°C) below the active heating setpoint, and turns off baseboard heat at 0.8°F (0.4°C) below the active heating setpoint. The range for activating the baseboard heat cannot be adjusted; however, the heating setpoint is configurable using the Rover service tool.

Baseboard heating is used most effectively when the discharge air temperature control high limit is set below 100°F (56°C). If this is done, the unit heat will maintain the temperature on light load days and the baseboard heat will be enabled to maintain the temperature on heavier load days.

CNT-SVX07D-EN 39

Page 40

Sequence of operations

Dehumidification

The Tracer ZN521 supports a dehumidification feature. Dehumidification is possible if the following are present:

• Mechanical cooling is available

• The heating capacity is located in the reheat position

• A zone humidity sensor is connected at AI4, or a relative humidity (RH) value is transmitted to the controller by a BAS.

• The Space RH Setpoint is valid (configurable using the Rover service tool)

• Dehumidification is enabled using the Rover service tool

The controller initiates dehumidification if the zone humidity exceeds the humidity setpoint. The controller continues to dehumidify until the sensed humidity falls below the setpoint minus the relative humidity offset.

The controller uses cooling and heating capacities simultaneously to dehumidify the space. While dehumidifying, the controller maintains the zone temperature at the active setpoint.

Note: Dehumidification is not available for face-and-bypass applications, and cannot be used if

the unit is in the unoccupied mode. Dehumidification disables the economizing function.

Peer-to-peer communication

Tracer ZN521 zone controllers have the ability to share data with other LonTalk-based controllers. Multiple controllers can be bound as peers, using the Rover service tool, to share:

•Setpoint

• Zone temperature

• Heating/cooling mode

•Fan status

• Unit capacity control

Shared data is communicated from one controller to any other controller that is bound to it as a peer. Applications having more than one unit serving a single zone can benefit by using this feature; it allows multiple units to share a single zone temperature sensor and prevents multiple units from simultaneously heating and cooling.

Unit protection strategies

The following strategies are initiated when specific conditions exist in order to protect the unit or building from damage:

• Smart reset

• Low-coil-temperature protection

• Condensate overflow

•Fan status

• Fan off delay

• Filter-maintenance timer

• Freeze avoidance

• Freeze protection (discharge air temperature low limit)

40 CNT-SVX07D-EN

Page 41

Smart reset

The Tracer ZN521 will automatically restart a unit that is locked-out as a result of a Low Coil Temp Detection (BI1) diagnostic. Referred to as “smart reset,” this automatic restart will occur 30 minutes after the diagnostic occurs. If the unit is successfully restarted, the diagnostic is cleared. If the unit undergoes another Low Coil Temp Detection diagnostic within a 24-hour period, the unit will be locked out until it is manually reset. (For more information on manual resetting, see

(latching) diagnostics,” p. 48).

Low-coil-temperature protection

See “BI1: Low-coil-temperature detection,” p. 14 and “Smart reset” in the current section.

Condensate overflow

See “BI2: Condensate overflow,” p. 14.

Fan status

The fan status is based on the status of the binary output(s) dedicated to fan control. The fan status is reported as high, medium, or low whenever the corresponding binary output is energized. The fan status is reported as off whenever none of the fan binary outputs are energized.

Additionally, a fan-status switch can be connected to BI4 to monitor the status of the fan for beltdriven or direct-driven units. The fan status switch provides feedback to the controller. If the fan is not operating when the controller has the fan controlled to on, the controller will generate a Low AirFlow—Fan Failure diagnostic.

If the controller energizes the fan output for 1 minute, and the fan status switch indicates no fan operation, the controller performs a unit shutdown and generates a Low AirFlow—Fan Failure diagnostic. If the fan has been operating normally for one minute, but the fan status switch indicates no fan operation, the same diagnostic is generated. This manual diagnostic discontinues unit operation until the diagnostic has been cleared from the controller. If a diagnostic reset is sent to the controller and the fan condition still exists, the controller attempts to run the fan for 1 minutes before generating another diagnostic and performing a unit shutdown.

Sequence of operations

“Manual

Fan off delay

After heating has been controlled off, the Tracer ZN521 keeps the fan energized for an additional 30 seconds. The purpose of this feature is to remove residual heat from the heating source.

Filter-maintenance timer

The filter-maintenance timer tracks the amount of time (in hours) that the fan is enabled. The Maintenance Required Timer Setpoint (configurable using the Rover service tool) is used to set the amount of time until maintenance (typically, a filter change) is needed. If the setpoint is configured to zero, the filter-maintenance timer is disabled.

The controller compares the fan-run time to Maintenance Required Timer Setpoint. Once the setpoint is reached, the controller generates a Maintenance Required diagnostic. When the diagnostic is cleared, the controller resets the filter-maintenance timer to zero, and the timer begins accumulating fan-run time again.

Freeze avoidance

Freeze avoidance is used for low ambient temperature protection. It is initiated only 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). The controller disables freeze avoidance when the outdoor air temperature rises 3°F (1.7°C) above the Freeze Avoidance Setpoint.

When the controller is in freeze-avoidance mode:

CNT-SVX07D-EN 41

Page 42

Sequence of operations

• Valves are driven open to allow water to flow through the coil

• Fan is off

• Face-and-bypass damper (when present) is at full bypass

• Economizing is disabled

• The outdoor/return air damper is closed

• DX cooling is off

• Electric heat stages are off

Freeze protection (discharge air temperature low limit)

The controller monitors the discharge air temperature with a 10 kΩ thermistor wired to analog input AI2. The freeze-protection operation is initiated whenever the discharge air temperature falls below the Discharge Air Temperature Low Limit. The Discharge Air Temperature Low Limit is configurable using the Rover service tool. During freeze protection, the controller increases the heating capacity or decreases the cooling capacity in order to raise the discharge air temperature above the low limit. If the discharge air temperature remains below the low limit for 3 minutes, the controller generates a Discharge Air Temp Limit diagnostic. See diagnostic on outputs.

Ta bl e 16, p. 49 for the effects of this

42 CNT-SVX07D-EN

Page 43

Status indicators for operation and communication

Green (status) LED

Tes t b ut t o n

Neuron ID label

Ye l l o w (communication) LED

Red (service) LED

Service pin button

This chapter describes the operation and communication status indicators on the Tracer ZN521 controller, including:

• A description of the location and function of the Test button and Service pin button and the lightemitting diodes (LEDs) located on the controller

• A complete list of the diagnostics that can occur, their effect on controller outputs, and an explanation of how diagnostics are cleared and the device restored to normal operation

Test button

The Test button is used to perform the manual output test (see “Manual output test” on page 43), which verifies that the controller output devices are operating properly. It is located on the Tracer ZN521 circuit board as shown in

Figure 19. Tracer ZN521 zone controller circuit board

Figure 19. You must remove the cover to access the Test button.

Manual output test

The manual output test sequentially turns on and off all binary outputs to verify their operation. The test overrides normal operation of the controller, which is suspended while the test is being performed.

Use the manual output test to:

• Verify output wiring and operation

• Force the water valve(s) open to balance the hydronic system

• Clear diagnostics and restore normal operation (although not a primary function of the manual output test)

The manual output test is performed either by repeatedly pressing the Test button to proceed through the test sequence or by using the Rover service tool. for non-face-and-bypass unit configurations in the sequence in which they are verified; Tab l e 12 on page 46 lists the outputs for face-and-bypass unit configurations in the sequence in which they are verified.

CNT-SVX07D-EN 43

Ta bl e 11 on page 45 lists the outputs

Page 44

Status indicators for operation and communication

The procedure is as follows:

1. Press and hold the Test button for 3 to 4 seconds, then release it to start the test mode. The green (status) LED goes off when you press the Test button, and then it blinks (as described in on page 47) when the Test button is released to indicate that the controller is in manual test mode.

2. Press the Test button (no more than once per second) to advance through the test sequence.

Ta bl e 11 and Ta b l e 12 show the resulting activities of the binary outputs.

Note: The outputs are not subject to minimum on or off times during the test sequence.

Ta bl e 14

44 CNT-SVX07D-EN

Page 45

CNT-SVX07D-EN 45

Table 11. Manual output test sequence for non-face-and-bypass configurations

Step Result BOP1 BOP2 BOP3 BOP4 BOP5 BOP6 BOP7 BOP8 BOP9 BOP10

Number of times

Test button is pressed

in sequence)

1 Begins test

2 Fan high2On/High Off Off Off Off Off Off Off Off Off 3 Fan

4 Fan low 5 Main open,

6 Main close,

7 Aux open,

8 Aux close,

9 Damper

10 Generic/

11: Exit

mode

medium

DX on

DX off, aux open, EH1 on

EH1 on, exhaust

fan

EH1 off, EH2 on, damper open

baseboard heat energized

The controller turns off all fan and electric heat outputs and drives all dampers and valves closed.

The controller attempts to clear all diagnostics.

If configured for a 3-speed fan, the medium fan speed output will energize at step 3. If configured for a 2-speed fan, the fan remains on high speed at step 3.

If configured for a 3-spe ed f an, the me dium fan sp eed outp ut en erg izes at st ep 4. If co nfi gur ed fo r a 2-spe ed fa n, th e l ow fa n speed output energizes at step 4. If configured for a 1-speed fan, the fan remains on high speed at step 4.

If the unit is configured for a 1- or 2-speed fan, the exhaust fan output energizes on step 7. The exhaust fan output is shared with medium fan speed.

After step 10, the manual output test performs an exit, which initiates a reset to restore the controller to normal operation.

Off Off Off Off On/Close Off 1) On/Close

Off 1) On/Med

Off Off On/Low Off Off Off Off Off Off Off On/High Off Off On/Open Off Off Off Off Off Off

On/High Off Off Off On/Close On/Open Off Off Off Off

On/High 1) Off

On/High Off Off Off Off Off On/Close On/Open Off Off

On/High Off Off Off Off Off Off Off On/Close Off

On/High Off Off Off Off Off Off Off Off On

Fan high

2) Off

2) On

1)Fan medium

2)Exhaust

Off Off Off Off Off Off Off Off

Off Off Off On/Open Off Off Off Off

Fan low

1)Cooling/changeover

valve, open

2)Two-position cooling/

changeover valve

3)DX compressor

Cooling/changeover

valve, close

1)Heating valve, open

2)Two-position heat valve

3)Electric heat, stage 1

2) Off

1)Heating valve, close

2)Electric heat, stage 2

Off On/Close Off

Outdoor air damper, open

Outdoor air damper, close

1)Generic

2)Baseboard heat

Status indicators for operation and communication

Page 46

46 CNT-SVX07D-EN

Table 12. Manual output test sequence for face-and-bypass configurations (two-position isolation valves only)

Step Result BOP1 BOP2 BOP3 BOP4 BOP5 BOP6 BOP7 BOP8 BOP9 BOP10

Number of times

Test button is pressed

in sequence)

1Begins test

mode 2Fan high 3Fan

medium 4Fan low 5 Main open,

Off Off Off Off Off Off On/Close Off On/Close Off

On/High Off Off Off On/Open Off Off Off Off Off Off 1) On/Med

Off Off On/Low Off On/Open Off Off Off Off Off On/High Off Off On/Open On/Open Off Off Off Off Off

DX on 6 Main close,

DX off, aux

open 7Aux open,

EH1 on,

exhaust

fan 8 Aux close,

damper

open 9Outdoor air

damper

close 10 Generic/

11: Exit

baseboard

heat

energized

The controller turns off all fan and electric heat outputs and drives all dampers and valves closed.

The controller attempts to clear all diagnostics.

If configured for a 3-speed fan, the medium fan speed output will energize at step 3. If configured for a 2-speed fan, the fan remains on high speed at step 3.

If configured for a 3-speed fan, the medium fan speed output energizes at step 4. If configured for a 2-speed fan, the low fan speed output energizes at step 4. If configured for a 1-speed fan, the fan remains on high speed at step 4.

If the unit is configured for a 1- or 2-speed fan, the exhaust fan output energizes on step 7. The exhaust fan output is shared with medium fan speed.

After step 10, the manual output test performs an exit, which initiates a reset to restore the controller to normal operation.

On/High Off Off Off On/Open On/Open Off Off Off Off

On/High 1) Off

On/High Off Off Off Off Off On/Close On/Open Off Off

On/High Off Off Off Off Off On/Close Off On/Close Off

On/High Off Off Off Off Off On/Close Off Off On

Fan high

2) Off

2) On

1)Fan medium

2)Exhaust fan

Fan low

Two-position cool/

changeover valve

Face and bypass damper,

open to face

Two-position heat valve

Face and bypass damper,

close (bypass)

Outdoor air damper, open

Off Off On/Open Off Off Off Off Off

Off Off On/Open On/Open Off Off Off Off

Outdoor air damper, close

1)Generic

Status indicators for operation and communication

2)Baseboard heat

Page 47

Service pin button

The Service pin button is located as shown in Figure 19 on page 43. The Service pin button is used to:

• Identify a device (see “Identifying a device” in the Rover Installation/Operation/Programming guide (EMTX-SVX01A-EN)

• Add a device to the active group (see “Adding a device” in EMTX-SVX01A-EN)

• Verify PCMCIA communications (see “Verifying PCMCIA communications” in EMTX-SVX01AEN)

• Make the green (status) LED “wink” to verify that the controller is communicating on the link (see Ta bl e 14 on page 47 and “Setting the Auto-wink option” in EMTX-SVX01A-EN)

Interpreting LEDs

The red (service) LED on the Tracer ZN521 controller (see Figure 19 on page 43) indicates whether the controller is capable of operating normally (see Ta b le 13).

Table 13. Red LED: Service indicator

LED is off continuously when power is applied to the controller.

LED is on continuously when power is applied to the controller.

LED flashes once every second. The controller is not executing the application

Restore the controller to normal operati on us ing the Rover service tool. Refer to EMTX-SVX01AEN for more information.

Status indicators for operation and communication

LED activity Explanation

The controller is operating normally.

The controller is not working properly, or someone is pressing the Service pin button.

software because the network connections and addressing have been removed.

The green (status) LED on the Tracer ZN521 controller (see Figure 19 on page 43) indicates whether the controller has power applied to it and if the controller is in manual test mode (see Tab le 14).

Table 14. Green LED: Status indicator

LED activity Explanation

LED is on continuously. Power is on (normal operation). LED blinks (one recurring blink). Manual output test mode is being performed

LED blinks (blinks twice as a recurring sequence).

LED blinks (1/4 second on, 1/4 second off for 10 seconds).

LED is off continuously. Either the power is off,

By sending a request from th e Rove r s ervic e to ol, you can r equ est the co nt roll er’s gre en LED to blink (“wink”), a notification that the controller received the signal and is communicating.

and no diagnostics are present. Manual output test mode is being performed

and one or more diagnostics are present. The Auto-wink option is activated, and the

controller is communicating.

the controller has malfunctioned, or the Test button is being pressed.

CNT-SVX07D-EN 47

Page 48

Status indicators for operation and communication

The yellow (communications) LED on the Tracer ZN521 controller (see Figure 19 on page 43) indicate the controller’s communication status (see Ta bl e 15).

Table 15. Yellow LED: Communications indicator

LED activity Explanation

LED is off continuously The controller is not detecting any

LED blinks. The controller detects communication (normal

LED is on continuously. Problem with communication link wiring

Diagnostics

Diagnostics are informational messages that indicate the operational status of the controller. In response to most diagnostics, the controller attempts to protect the equipment by enabling or disabling, or opening or closing, specific outputs. Other diagnostics provide information about the status of the controller, but have no effect on outputs. Diagnostics are reported in the order in which they occur. Multiple diagnostics can be present simultaneously. Diagnostic messages are viewed using the Rover service tool or through a BAS.

communication (normal for stand-alone applications).

for communicating applications, including data sharing).

(possible need for termination resistor), or controller failure (caused by power surge, lightning strike, etc.)

Types of diagnostics

Diagnostics are categorized according to the type of clearing method each uses and the type of information each provides.

The four categories are:

• Manual (latching)

• Automatic (nonlatching)

•Smart reset

• Informational

Note: Clearing diagnostics refers to deleting diagnostics from the software; it does not affect the

Manual (latching) diagnostics

Manual diagnostics (also referred to as latching) cause the unit to shut down. Manual diagnostics can be cleared from the controller in one of the following ways:

• By using the Rover service tool (see “Resetting a diagnostic” in EMTX-SVX01A-EN, Rover

• Through a building automation system (see product literature)

• By initiating a manual output test at the controller (see “Manual output test” on page 43)

• By cycling power to the controller. When the 24 Vac power to the controller is cycled off and then

• By turning the zone sensor fan switch to OFF and then back to any other setting. (This feature

problem that generated the message. For help with diagnosing a problem, see

“Troubleshooting,” p. 51.

Installation/Operation/and Programming guide).

on again, a power-up sequence occurs.

will be available beginning with controller software version 2.10.)

Automatic (nonlatching) diagnostics

Automatic diagnostics clear automatically when the problem that generated the diagnostic is solved.

48 CNT-SVX07D-EN

Page 49

Status indicators for operation and communication

Smart reset diagnostics

After the controller detects the first smart reset diagnostic, the unit waits 30 minutes before initiating the smart reset function. If another diagnostic of this type occurs again within 24 hours after an automatic clearing, you must clear the diagnostic manually by using any of the ways shown

“Manual (latching) diagnostics.”

for

Informational diagnostics

Informational diagnostics provide information about the status of the controller. They do not affect machine operation. They can be cleared from the controller using any of the ways shown for “Manual (latching) diagnostics.”

Table of diagnostics

Ta bl e 16 presents each diagnostic that can be generated by the Tracer ZN521, its effect on outputs

(consequences), and its type.

Note: The generic binary output is unaffected by diagnostics.

Table 16. Diagnostics

Diagnostic Probable cause Consequences

Maintenance Required Fan run hours exceed the time set

Condensate Overflow The drain pan is full of water Fan off

Low Coil Temp Detection The leaving fluid temperature

Low Airflow—Fan Failure The fan drive belt, contactor, or

Space Temperature Failure Invalid or missing value for zone

Entering Water Temp Failure Invalid or missing value for z one

Discharge Air Temp Limit Discharge air temperature has

to indicate filter change

may be close to freezing

motor has failed.

temperature

fallen below the Discharge Air Temperature Low Limit

Fan unaffected Valves unaffected Electric heat unaffected Face and bypass damper unaffected

Valves closed Outdoor air damper closed Face and bypass damper bypass DX/electric heat off Baseboard heat off

Fan off Valves open Outdoor air damper closed Face and bypass damper bypass DX/electric heat off Baseboard heat off

Fan off Valves closed Outdoor air damper closed Face and bypass damper bypass DX/electric heat off Baseboard heat off

Fan unaffected (enabled) Valves unaffected Outdoor air damper unaffected Face and bypass damper unaffected DX/electric heat unaffected Baseboard heat off

Fan off Valves open Outdoor air damper closed Face and bypass damper bypass DX/electric heat off Baseboard heat off

Diagnostic

type

Informational

Manual

Smart reset/ Manual

Manual

Automatic

CNT-SVX07D-EN 49

Page 50

Status indicators for operation and communication

Table 16. Diagnostics (continued)

Diagnostic Probable cause Consequences

Discharge Air Temp Failure Invalid or missing value for

Outdoor Air Temp Failure Invalid or missing value for

Humidity Input Failure Invalid or missing value for

CO2 Sensor Failure Invalid or missing value for CO2 Fan unaffected

Generic AIP Failure Invalid or missing value for

Local Fan Mode Failure Invalid or missing fan-speed

Local Setpoint Failure Invalid or missing value for zone

Generic Temperature Failure Invalid or missing generic

Invalid Unit Configuration Software is configured

Normal On start-up Fan unaffected

discharge air temperature

outdoor air temperature

relative humidity

generic analog input

switch (reverts to default fan speed)

temperature setpoint (reverts to default setpoint)

temperature value

improperly

Fan off Valves closed Outdoor air damper closed Face and bypass damper bypass DX cooling/electric heat off Baseboard heat off

Fan unaffected Valved unaffected Outdoor air damper minimum

position

Face and bypass damper unaffected DX cooling/electric heat unaffected Baseboard heat unaffected

Fan unaffected Valves unaffected Outdoor air damper unaffected Face and bypass damper unaffected DX cooling/electric heat unaffected Baseboard heat unaffected Dehumidification sequence off

Valves unaffected Outdoor air damper unaffected Face and bypass damper unaffected DX cooling/electric heat unaffected Baseboard heat unaffected

Fan unaffected Valves unaffected Outdoor air damper unaffected Face and bypass damper unaffected DX cooling/electric heat unaffected Baseboard heat unaffected

Fan off Valves off Outdoor air damper closed Face and bypass damper closed DX cooling/electric heat off Baseboard heat off

Valves unaffected Electric heat unaffected Compressors unaffected Damper unaffected

Diagnostic

type

Automatic

Informational

Automatic

Informational

Manual

Automatic

50 CNT-SVX07D-EN

Page 51

Troubleshooting

Use Ta bl e 17 through Ta bl e 22 to assist you in diagnosing any of the following operational problems that you might encounter with the Tracer ZN521 zone controller:

• Fan does not energize (Ta bl e 17)

• Valves remain closed (Table 18 on page 52)

• Valves remain open (Table 19 on page 52)

• Compressors are not running (Table 20 on page 53)

• Electric heat does not energize (Table 20 on page 53)

• An outdoor air damper stays closed (Table 21 on page 53)

• An outdoor air damper stays open (Table 22 on page 54)

Table 17. Fan does not energize

Probable cause Explanation

Unit wiring The wiring between the controller outputs and the fan relays and contacts must be pres-

ent and correct for normal fan operation. Refer to applicable wiring diagram.

Failed end device The fan motor and relay must be checked to ensure proper operation.

Normal operation The fan will turn off when the controller receives a communicated off signal, when the

fan-speed switch is set to OFF, when specific diagnostics are generated, or when the default fan speed is set to Off and the fan is operating in the Auto mode. If the controller is in unoccupied mode, the fan cycles between off and the highest fan speed.

No power to the controller

Power-up control-wait If power-up control-wait is enabled (non-zero time), the controller remains off until one of

Diagnostic present Several diagnostics affect fan operation. For information about these diagnostics, see

Unit configuration The controller must be properly configured based on the actual installed end devices and

Manual output test The controller includes a manual output test sequence you can use to verify output oper-

Random start observed

Cycling fan operation/ continuous

Unoccupied operation Even if the controller is configured for continuous fan operation, the fan normally cycles

Fan mode off If a local fan mode switch determines the fan operation, the off position controls the fan

Requested mode off You can communicate a desired operating mode (such as off, heat, and cool) to the con-

If the controller does not have power, the unit fan does not operate. For the Tracer ZN521 controller to operate normally, it must have an input voltage of 24 Vac. If the green LED is off continuously, the controller does not have sufficient power or has failed.

two conditions occurs:

1) The controller exits power-up control-wait after it receives communicated information.

2) The controller exits power-up control-wait after the power-up control-wait time expires.

Ta bl e 16, p. 49.

application. If the unit configuration does not match the actual end device, the fans may not work correctly.

ation and associated output wiring. However, based on the current step in the test sequence, the unit fan may not be on. Refer to the

After power-up, the controller always observes a random start from 5 to 30 seconds. The controller remains off until the random start time expires.

The controller operates the fan continuously when in the occupied, occupied standby, or occupied bypass mode. When the controller is in the unoccupied mode, the fan is cycled between high speed and off with capacity.

with capacity during unoccupied mode. While unoccupied, the fan cycles on or off with heating/cooling to provide varying amounts of heating or cooling to the space.

off.

troller. If off is communicated to the controller, the unit controls the fan off. There is no heating or cooling.

“Manual output test,” p. 43.

CNT-SVX07D-EN 51

Page 52

Troubleshooting

Table 18. Valves remain closed

Probable cause Explanation

Unit wiring The wiring between the controller outputs and the valve(s) must be present and correct

for normal valve operation. Refer to applicable wiring diagram.

Failed end device The valves must be checked to ensure proper operation.

No power to the controller

Power-up control-wait If power-up control-wait is enabled (non-zero time), the controller remains off until one of

Diagnostic present Several diagnostics affect valve operation. For information about these diagnostics, see

Normal operation The controller opens and closes the valves to meet the unit capacity requirements.

Unit configuration The controller must be properly configured based on the actual installed end devices and

Manual output test The controller includes a manual output test sequence you can use to verify output oper-

Random start observed

Requested mode off You can communicate a desired operating mode (such as off, heat, and cool) to the con-

Entering water temperature sampling logic

Valve configuration Make sure the valves are correctly configured, using the Rover service tool, as normally

If the controller does not have power, the unit valve(s) will not operate. For the Tracer ZN521 controller to operate normally, you must apply an input voltage of 24 Vac. If t h e green LED is off continuously, the controller does not have sufficient power or has failed.

two conditions occurs:

1) The controller exits power-up control-wait after it receives communicated information.

2) The controller exits power-up control-wait after the power-up control-wait time expires.

Ta bl e 16, p. 49.

application. If the unit configuration does not match the actual end device, the valves may not work correctly.

ation and associated output wiring. However, based on the current step in the test sequence, the valves may not be open. Refer to the “Manual output test,” p. 43.

After power-up, the controller always observes a random start from 5 to 30 seconds. The controller remains off until the random start time expires.

troller. If off is communicated to the controller, the unit controls the fan off. There is no heating or cooling.

The controller includes entering water temperature sampling logic, which is automatically initiated during 2-pipe and 4-pipe changeover if the entering water temperature is either too cool or too hot for the desired heating or cooling. (See

“AI1: Entering water

temperature,” p. 16.)

open or normally closed as dictated by the application.

Table 19. Valves remain open

Probable cause Explanation

Unit wiring The wiring between the controller outputs and the valve(s) must be present and correct

for normal valve operation. Refer to applicable wiring diagram.

Failed end device The valves must be checked to ensure proper operations.

Normal operation The controller opens and closes the valves to meet the unit capacity requirements.

Manual output test The controller includes a manual output test sequence you can use to verify output oper-

ation and associated output wiring. However, based on the current step in the test sequence, the values may not be open. refer to the

“Manual output test,” p. 43.

Diagnostic present Several diagnostics affect valve operation. For information about these diagnostics, see

Ta bl e 16, p. 49.

Unit configuration The controller must be properly configured based on the actual installed end devices and

application. If the unit configuration does not match the actual end device, the valves may not work correctly.

52 CNT-SVX07D-EN

Page 53

Troubleshooting

Table 19. Valves remain open (continued)

Probable cause Explanation

Entering water temperature sampling logic

Valve configuration Make sure the valves are correctly configured, using the Rover service tool, as normally

Freeze avoidance When the fan is off with no demand for capacity (0%) and the outdoor air temperature is

Table 20. DX or electric heat does not energize

Probable cause Explanation

Unit wiring The wiring between the controller outputs and the end devices must be present and cor-

Failed end device Check the control contactors or the electric heat element, including any auxiliary safety

No power to the controller

Diagnostic present Several diagnostics affect DX and electric heat operation. For information about these

Normal operation The controller controls compressor or electric heat outputs as needed to meet the unit

Unit configuration

Manual output test The controller includes a manual output test sequence you can use to verify output oper-

Requested mode off You can communicate a desired operating mode (such as off, heat, and cool) to the con-

Freeze avoidance When the fan is off with no demand for capacity (0%) and the outdoor air temperature is

ture,” p. 16.)

open or normally closed as dictated by the application.

below the freeze avoidance setpoint, the controller opens the water valves (100%) to prevent coil freezing. This includes unoccupied mode when there is no call for capacity or any other time the fan is off.

rect for normal operation. Refer to applicable wiring diagram.

interlocks, to ensure proper operation.

If the controller does not have power, heat outputs do not operate. For the Tracer ZN521 controller to operate normally, you must apply an input voltage of 24 Vac. If the green LED is off continuously, the controller does not have sufficient power or has failed.

diagnostics, see Ta b le 16, p. 49.

capacity requirements.

The controller must be properly configured based on the actual installed end devices and application. If the unit configuration does not match the actual end device, DX or electric heat may not operate correctly.

ation and associated output wiring. However, based on the current step in the test sequence, the DX or electric heat outputs may be off. Refer to the

“Manual output test,”

p. 43.

troller. If off is communicated to the controller, the unit shuts off the compressor or electric heat.

below the freeze avoidance setpoint, the controller disables compressors and electric heat outputs (100%) to prevent coil freezing. This includes unoccupied mode when there is no call for capacity or any other time the fan is off.

Table 21. Outdoor air damper remains closed

Probable cause Explanation

Unit wiring The wiring between the controller outputs and the outdoor air damper must be present

and correct for normal outdoor air damper operation. Refer to applicable wiring diagram.

Failed end device Check damper actuator to ensure proper operation.

CNT-SVX07D-EN 53

Page 54

Troubleshooting

Table 21. Outdoor air damper remains closed (continued)

Probable cause Explanation

No power to the controller

Diagnostic present Several diagnostics affect outdoor air damper operation. For information about these

Normal operation

Unit configuration The controller must be properly configured based on the actual installed end devices and

Manual output test The controller includes a manual output test sequence you can use to verify output oper-

Warm-up and cooldown sequence

Requested mode off You can communicate a desired operating mode (such as off, heat, or cool) to the control-

If the controller does not have power, the outdoor air damper does not operate. For the Tracer ZN521 controller to operate normally, you must apply an input voltage of 24 Vac. If the green LED is off continuously, the controller does not have sufficient power or has failed.

diagnostics, see Ta b le 16, p. 49.

The controller opens and closes the outdoor air damper based on the controller’s occupancy mode and fan status. Normally, the outdoor air damper is open during occupied mode when the fan is running and closed during unoccupied mode.

application. If the unit configuration does not match the actual end device, the outdoor air damper may not work correctly.

ation and associated output wiring. However, based on the current step in the test sequence, the outdoor air damper may not be open. Refer to the “Manual output test,”

p. 43.

The controller includes both a morning warm-up and cool-down sequence to keep the outdoor air damper closed during the transition from unoccupied to occupied. This is an attempt to bring the space under control as quickly as possible.

ler. If off is communicated to the controller, the unit closes the outdoor air damper.

Table 22. Outdoor air damper remains open

Probable cause Explanation

Unit wiring The wiring between the controller outputs and the outdoor air damper must be present

and correct for normal outdoor air damper operation. Refer to applicable wiring diagram.

Failed end device Check damper actuator to ensure proper operation.

Normal operation

“Modulating

outdoor/return air dampers,” p. 37.

Unit configuration

The controller must be properly configured based on the actual installed end devices and application. If the unit configuration does not match the actual end device, the outdoor air damper may not work correctly.

Manual output test The controller includes a manual output test sequence you can use to verify output oper-

ation and associated output wiring. However, based on the current step in the test sequence, the outdoor air damper may be open. Refer to the

“Manual output test,” p. 43.

54 CNT-SVX07D-EN

Page 55

Index

Numerics

24 Vac wiring 10

AC-power wiring 10 Actuators

Damper 9, 39 Valve 9

Additional application-dependent

components

Addressing

LonTalk communication 11 Neuron IDs 11

Agency listing/compliance 7 Analog inputs

AI1 (Entering water

temperature)

AI2 (Discharge air

temperature)

AI3 (Outdoor air

temperature)

AI3 configuration options 16 AI4 (Universal 4–20 mA) 17 AI4 configuration options 17 AI4 configured for CO2

measurement

AI4 configured for RH

measurement

AI4 generic configuration 17 FAN (Fan mode input) 15 Generic temperature 16 SET (Local setpoint) 15 ZN (Zone temperature) 15

Applications 6, 13–30 Applications table ASHRAE Cycle 1

Agency listing/compliance 8 Operation 38

ASHRAE Cycle 2

Agency listing/compliance 8 Operation 38

8–9

14–17

BAS communication 6, 11 Baseboard heat

Operation 39 Supported application 18

Binary inputs 13–14

BI1 (Low-coil-temperature

detection)

BI2 (Condensate overflow) 14 BI3 (Occupancy or generic) 14

BI3 configuration options 14 BI4 (Fan status) 14 Switching devices 9

Binary outputs 18–19

Generic 19 Manual output test 43 Output devices 9 Overriding 19 Table of supported options 18

Blower coils 6, 18 Building automation system

communication

6, 11

CE, <Emphasis>see Agency listing/

compliance Circuit board Clearances Clearing diagnostics CO2

Measurement input 17 Sensor 9, 17 Sensor failure diagnostic 50

Condensate overflow

Diagnostic 49 Input 14 Switch 9, 14

Configuration options

AI3 (Outdoor air temperature or

AI4 (Generic, CO2 measurement,

BI3 (Occupancy or generic) 14 DX cooling 6 Electric heat 6 Face-and-bypass dampers 6 Outdoor/return air dampers 6 Rover service tool 6 Tri-state modulating dampers 6 Tri-state modulating valves 6 Two-position valves 6

Current-sensing switches 9

generic)

or RH measurement)

Dampers

Actuators 9 Exhaust 35 Face-and-bypass 6, 18, 39 Modulating outdoor/return

air

37, 39

Outdoor/return air 6, 18, 35, 37 Supported applications 6, 18

Tri-state modulating 6 Two-position control 39

Data sharing 40 Dehumidification Device addressing for BAS

communication

Diagnosing operational

problems

Diagnostics

Automatic 48 Clearing 48 CO2 Sensor Failure 50 Condensate Overflow 49 Discharge Air Temp Failure 50 Discharge Air Temp Limit 49 Entering Water Temp Failure 49 Freeze protection 49 Generic AIP Failure 50 Generic Temperature Failure 50 Humidity Input Failure 50 Informational 49 Invalid Unit Configuration 50 Latching 48 Local Fan Mode Failure 50 Local Setpoint Failure 50 Low Coil Temp Detection 49 Maintenance (filter change) 49 Manual 48 Nonlatching 48 Normal 50 Outdoor Air Temp Failure 50 Smart reset 49 Table 49 Types 48 Zone Temp Failure 49

Dimensional diagram 7 Dimensions Discharge air temperature

Failure diagnostic 50 Low limit diagnostic 49

Discharge air temperature input 16 Discharge air temperature low

limit

Discharge air tempering DX cooling

Operation 39 Supported application 18 Troubleshooting 53

51–54

Economizing 16, 38

CNT-SVX07D-EN 55

Page 56

Index

Electric heat

Operation 39 Supported application 18 Troubleshooting 53

Entering water temperature

Diagnostic 49 Input 16 Sampling function 35

Equipment supported 6, 13, 18 Exhaust control

Fan

Exhaust 35 Mode input 15 Operation 35 Supply 35 Troubleshooting 51

Fan coils 6, 18 Fan off delay Fan status

Input 14 Switching devices 9 Unit protection 41

Filter-maintenance timer 41 Four-pipe operation Free cooling, <Emphasis>see

Economizing Freeze avoidance Freeze protection Freeze-protection switch

16, 41 42

9, 14

Generic

Binary input 14 Binary output 49 Temperature input 16

Generic AIP failure diagnostic 50 Generic binary input Generic binary output Generic temperature failure

diagnostic

Heating or cooling mode 34 Humidity

Input failure diagnostic 50 Measurement input 17 Zone sensor 17

Hydronic cooling 18

Informational diagnostics 49

Input/output functions Input/output terminal wiring Invalid unit configuration

diagnostic

Isolation valve operation

13–30

LEDs

General 43 Interpreting green (status) 47 Interpreting red (service) 47 Interpreting yellow

(communications)

Location 43

Local fan mode input failure

diagnostic Local setpoint failure diagnostic Local setpoint input LonTalk communication

Description 6 Termination resistors 11 Wiring and addressing 11

LonTalk protocol, <Emphasis>see

LonTalk communication Low-coil-temperature detection

Diagnostic 14, 49 Input 14

Manual output test 43 Modulating outdoor/return air

dampers Modulating valves

Morning cool-down 34 Morning warm-up Mounting

Calibration 36 Operation 36

Cover 12 Diagram 12 Location 12 Operating environment 12 Procedures 12

National Electrical Code 10, 11 Neuron IDs

Description 11 Location of label 43

Occupancy

Switch 14

Switching devices 9

Occupancy input 14 Occupancy modes

General 31 Occupied 32 Occupied bypass 32 Occupied standby 32 Unoccupied 32

Operating environment 12 Outdoor air damper

Troubleshooting 53

Outdoor air temperature

Failure diagnostic 50 Input 16

Outdoor air temperature input 16 Outdoor/return air dampers Output devices Overriding binary outputs

General 43

Peer-to-peer communication 40 Power transformers Power wiring Power-up sequence Product description Protection strategies, <Emphasis>see

Unit protection strategies

8, 10

Random start 31 Rover service tool

Adding a device 47 Configuring the controller 6 Identifying a device 47 User guide 6 Verifying LonTalk

communication

Verifying PCMCIA

communications

Sensor

Humidity 40

Sensors

Application-specific 17 CO2 9, 17 Table of options 9 Water and duct temperature 8 Zone humidity 9, 17 Zone temperature 9

Sequence of operations 31–42

56 CNT-SVX07D-EN

Page 57

Index

ASHRAE Cycle 1 38 ASHRAE Cycle 2 38 Baseboard heat 39 Dehumidification 40 Discharge air temperature low

limit

DX cooling 39 Economizing 38 Electric heat 39 Exhaust control 35 Face-and-bypass damper 39 Fan off delay 41 Fan operation 35 Fan status 41 Filter-maintenance timer 41 Four-pipe operation 37 Freeze avoidance 41 Freeze protection 42 Heating/cooling mode 34 Isolation valve 39 Modulating-valve calibration 36 Modulating-valve operation 36 Morning cool-down 34 Morning warm-up 34 Occupancy modes 31 Outdoor/return air 37 Peer-to-peer communication 40 Power-up sequence 31 Random start 31 Smart reset 41 Timed override control 32 Two-pipe operation 37 Two-position damper

control

Two-position valve

operation

Unit protection strategies 40 Valves 36 Zone temperature control 33

Service pin button 43, 47 Smart reset

Diagnostic 41, 49 Unit protection 41

Specifications

AC power wiring 10 Agency listing/compliance 7 Clearances 7 Dimensional diagram 7 Dimensions 6 Input/output terminal wiring 10 LonTalk communication wiring

and addressing

Storage environment 6 Transformers 11

Status indicators for operation and

communication

Diagnostics 48 General 43 Green (status) LEDs 47 LEDs 43 Manual output test 43 Red (service) LEDs 47 Service pin button 47 Test button 43 Yellow (communication)

LEDs

Storage environment 6 Switching devices

Condensate overflow 9, 14 Current sensing 9 Fan status 9 Freeze protection 9, 14 Low-coil-temperature 9 Occupancy 9, 14

Temperature sensors

Table of options 9 Water and duct 8 Zone 9

Termination resistors 11 Test button Timeclock Timed override control Transformers Troubleshooting

Two-pipe operation 37 Two-position damper control Two-position valve operation Types of diagnostics

43–44

8, 10, 11

DX cooling 53 Electric heat failure 53 Fans 51 Outdoor air damper 53 Valves 52

UL, <Emphasis>see Agency listing/

compliance Unit protection strategies

Condensate overflow 41 Discharge air temperature low

limit

Fan off delay 41

Fan status 41 Filter-maintenance timer 41 Freeze avoidance 41 Freeze protection 42 Low-coil-temperature

protection

Smart reset 41

Unit ventilators 6, 18 Universal 4–20 mA

Valves

Actuators 9 Calibration of modulating 36 Four-pipe operation 37 General operation 36 Isolation-valve operation 36 Operation of modulating 36 Operation of two-position 36 Supported applications 6, 18,

Tri-state modulating 6, 18, 36 Troubleshooting 52 Two-pipe operation 37 Two-position 6, 18

Water and duct temperature

sensors

Wiring

Wiring diagrams 19–30

BAS communication 11 Compliance with National

Electrical Code

Input/output terminals 10 LonTalk communication 11 Minimum requirements 19 Requirements and options 19–

Electric heat unit 27 Electric heat unit with DX

cooling

Four-pipe heating/cooling unit

with auto changeover

Four-pipe heating/cooling unit

with face-and-bypass damper

Four-pipe hydronic heating/

cooling unit

Two-pipe heating unit with DX

cooling

Two-pipe heating/cooling unit

with face-and-bypass damper 29

10, 11

CNT-SVX07D-EN 57

Page 58

Index

Two-pipe hydronic heating/

cooling unit with auto changeover

Two-pipe hydronic-cooling

unit

Two-pipe hydronic-heating

unit

Zone humidity

Sensor 9

Zone temperature

Input 15 Sensors 9

Zone temperature control 33 Zone temperature failure

diagnostic 49

58 CNT-SVX07D-EN

Page 59

Page 60

Trane optimizes the performance of homes and buildings around the world. A business of Ingersoll Rand, the leader in creating and sustaining safe, comfortable and energy efficient environments, Trane offers a broad portfolio of advanced controls and HVAC systems, comprehensive building services, and parts. For more information, visit www.Trane.com.

Trane has a policy of continuous product and product data improvement and reserves the right to change design and specifications without notice.

CNT-SVX07D-EN 08 Nov 2010

Supersedes CNT-SVX07C-EN (01 Apr 2005)

Trane Tracer ZN521 Installation And Operation Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

Tracer™ ZN521 Zone Controller

Overview and specifications

Product description

Storage environment

Dimensions

Plastic-cover model dimensions

Metal-cover model dimensions

Clearances

Plastic-cover model (see Figure 1 on page 7)

Metal-cover model (see Figure 2 on page 8)

Agency listing/compliance

Additional components

Power transformer

Water, duct, and outdoor-air temperature sensors

Binary input switching devices

Output devices

Zone temperature sensors

Valve actuators

Damper actuators

Zone humidity sensor

CO2 sensor

General wiring information

Input/output terminal wiring

AC power wiring

Communication-link wiring and addressing

Mounting the controller

Location recommendations

Operating environment requirements

Mounting recommendations

Input/output functions and wiring for typical applications

Binary inputs

BI1: Low-coil-temperature detection

BI2: Condensate overflow

BI3: Occupancy or generic binary input

BI4: Fan status

Analog inputs

GND: Ground terminals

ZN: Zone temperature

SET: Local setpoint

FAN: Fan mode input

AI1: Entering water temperature

AI2: Discharge air temperature

AI3: Outdoor air temperature or generic temperature

AI4: Universal 4–20 mA

Binary outputs

Generic binary output

Overriding binary outputs

Wiring requirements and options

Sequence of operations

Power-up sequence

Random start

Occupancy modes

Occupied mode

Unoccupied mode

Occupied standby mode

Occupied bypass mode

Timed override control

Zone temperature control

Cascade zone control

Simplified zone control

Discharge air tempering

Morning warm-up

Morning cool-down

Heating or cooling mode

Entering water temperature sampling function

Fan operation

Exhaust control

Valve operation

Modulating valve operation

Modulating valve calibration

Two-position valve operation

Isolation-valve operation

Two-pipe operation

Four-pipe operation

Modulating outdoor/return air dampers

ASHRAE Cycle 1 conformance