Trane ZN521 Zone Controller Installation and Operation Manual

Below you will find brief information for Zone Controller ZN521. This manual provides installation and operational details for the Trane Tracer ZN521 zone controller, a device for direct-digital zone temperature control. It can function independently or within a building automation system (BAS) via a LonTalk communication link. The ZN521 controls various HVAC components such as fan coils, unit ventilators, and blower coils, managing valves, dampers, DX cooling, and electric heat.

PDF

Document

Installation and

Operation

Tracer

™

ZN521

Zone Controller

CNT-SVX07C-EN

Installation and

Operation

Tracer

™

ZN521

Zone Controller

CNT-SVX07C-EN

April 2005

CNT-SVX07C-EN

Tracer ZN521 Zone Controller Installation and Operation

This guide and the information in it are the property of American Standard Inc. and may not be used or reproduced in whole or in part, without the written permission of American Standard Inc. Trane, a business of American Standard, Inc., has a policy of continuous product and product data improvement and reserves the right to change design and specification without notice.

Although Trane has tested the hardware and software described in this guide, no guarantee is offered that the hardware and software are error free.

Trane reserves the right to revise this publication at any time and to make changes to its content without obligation to notify any person of such revision or change.

Trane may have patents or patent applications covering items in this publication. By providing this document, Trane does not imply giving license to these patents.

™

The following are trademarks or registered trademarks of American Standard Inc.: Trane, Tracer, Rover.

™

The following are trademarks or registered trademarks of their respective companies or organizations: BACnet from

ASHRAE; Neuron, LonMark, LonTalk, and LonWorks from Echelon Corporation; National Electrical Code form the National

Fire Proctection Association, Inc.

Printed in the U.S.A.

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NOTICE:

Warnings and Cautions appear at appropriate sections throughout this manual. Read these carefully:



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, may result in minor or moderate injury.

It may also be used to alert against unsafe practices.

CAUTION

Indicates a situation that may result in equipment damage or property damage.

The following format and symbol conventions appear at appropriate sections throughout this manual:

IMPORTANT

Alerts installer, servicer, or operator to potential actions that could cause the product or system to operate improperly but will not likely result in potential for damage.

Note:

A note may be used to make the reader aware of useful information, to clarify a point, or to describe options or alternatives.

◆ This symbol precedes a procedure that consists of only a single step.

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Chapter 1 Overview and specifications . . . . . . . . . . . . . . . . . . 1

Product description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Storage environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Clearances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Agency listing/compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Additional components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Power transformer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Water, duct, and outdoor-air temperature sensors . . . . . . . . . . . . . . 4

Binary input switching devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Output devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Zone temperature sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Valve actuators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Damper actuators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Zone humidity sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

CO2 sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Chapter 2 General wiring information . . . . . . . . . . . . . . . . . . . 7

Input/output terminal wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

AC-power wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Communication-link wiring and addressing . . . . . . . . . . . . . . . . . . . . . . 9

Chapter 3 Mounting the controller . . . . . . . . . . . . . . . . . . . . 11

Location recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

Operating environment requirements . . . . . . . . . . . . . . . . . . . . . . . . . . .11

Mounting recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Chapter 4 Input/output functions and wiring for typical applications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Binary inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

BI1: Low-coil-temperature detection . . . . . . . . . . . . . . . . . . . . . . . . 14

BI2: Condensate overflow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

BI3: Occupancy or generic binary input . . . . . . . . . . . . . . . . . . . . . . 15

BI4: Fan status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Contents ii

Analog inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

GND: Ground terminals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

ZN: Zone temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

SET: Local setpoint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

FAN: Fan mode input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

AI1: Entering water temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

AI2: Discharge air temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

AI3: Outdoor air temperature or generic temperature . . . . . . . . . . 18

AI4: Universal 4–20 mA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Binary outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Generic binary output. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Overriding binary outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Wiring requirements and options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Chapter 5 Sequence of operations . . . . . . . . . . . . . . . . . . . . 35

Power-up sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Random start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Occupancy modes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Occupied mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Unoccupied mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Occupied standby mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Occupied bypass mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Timed override control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Zone temperature control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Cascade zone control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Simplified zone control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Discharge air tempering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Morning warm-up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Morning cool-down. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Heating or cooling mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Entering water temperature sampling function . . . . . . . . . . . . . . . . . . . 40

Fan operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Exhaust control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Valve operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Modulating valve operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Modulating valve calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Two-position valve operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Isolation-valve operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Two-pipe operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Four-pipe operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

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Contents

Modulating outdoor/return air dampers. . . . . . . . . . . . . . . . . . . . . . . . . 43

ASHRAE Cycle 1 conformance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

ASHRAE Cycle 2 conformance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Economizing (free cooling) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Two-position control of a modulating outdoor air damper . . . . . . . . . 46

Face-and-bypass damper operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Face-and-bypass, isolation-valve operation . . . . . . . . . . . . . . . . . . 46

DX cooling operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Electric heat operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Baseboard heat operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Dehumidification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Peer-to-peer communication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Unit protection strategies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Smart reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Low-coil-temperature protection . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Condensate overflow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Fan status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Fan off delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Filter-maintenance timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

Freeze avoidance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

Freeze protection (discharge air temperature low limit) . . . . . . . . 50

Chapter 6 Status indicators for operation and communication. . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Test button. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Manual output test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

Service pin button. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

Interpreting LEDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

Types of diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

Manual (latching) diagnostics. . . . . . . . . . . . . . . . . . . . . . . . . . . 58

Automatic (nonlatching) diagnostics . . . . . . . . . . . . . . . . . . . . . 58

Smart reset diagnostics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

Informational diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

Table of diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

iii

Contents

Chapter 7 Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

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Chapter 1

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

Rover Installation/Operation/Programming guide (EMTX-

SVX01A-EN).

Chapter 1 Overview and specifications

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 3.

• 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 3.

• Height: 9.0 in (25 mm)

• Width: 10.37in. (263 mm)

• Depth: 2.25 in. (58 mm)

Clearances

Plastic-cover model

(see Figure 1 on page 3)

• 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 3)

• Front: 24.0 in. (610 mm)

• Each side: 2.0 in. (51 mm)

• Top and bottom: 1.0 in. (25 mm)

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Clearances

Figure 1. Plastic-cover model dimensions and clearances

1 in

(25 mm)

4 in

(102 mm)

4 in.

(102 mm)

5.625 in.

(143 mm)

6.31

(160 mm)

4 in

(102 mm)

6.875 in

(175 mm)

5.625 in (143 mm)

1 in

(25 mm)

Figure 2. Metal-cover model dimensions and clearances

1 in.

(25 mm) 1.875 in.

(48 mm)

6.5 in.

(165 mm)

2 in. (51 mm)

0.28 in.

(7 mm)

9 in.

(229 mm)

9 in.

(229 mm)

2 in.

(51 mm)

24 in.

(610 mm)

10.37 in.

(263 mm) width with cover

Clearances

Dimensions

1 in.

(25 mm)

7 in.

(178 mm)

2 in.

(51 mm)

1 in.

(25 mm)

2.25in.

(58 mm)

10.25 in.

(260 mm) width without cover

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Chapter 1 Overview and specifications

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.

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 VA) and its associated output devices, including relays and actuators, to a maximum of 12 VA per output utilized.

Water, duct, and outdoor-air temperature sensors

Temperature sensors must be Trane 10 k

Ω

(at 25°C) thermistors. Entering water and discharge air inputs may use a sealed temperature sensor

(part number 4190 1100).

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

Table 1 shows the Trane zone temperature sensors that are supported by

the Tracer ZN521 zone controller.

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

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Additional components

Table 1. Tracer zone temperature sensor options

BAS order number

Use

4190 1087 Any

4190 1088 Any

4190 1090 Any

4190 1094 Any

4190 1095 Unit ventilator

4190 1115 Fan coil

4190 1116 Unit ventilator

4190 1117 Any

Fan Zone

High Med Low Auto Off x x x

Setpoint thumbwheel

Temperature sensor

On x x x x x x x x x x x x x x x x x x x x x x x x x x

Timed override buttons

Cancel x x x x x

Comm jack x x x x x x x x x x x x x 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 a 4–20 mA output, where 4 mA is 0% RH and

20 mA is 100% RH. The controller provides 20 Vdc to power the zone humidity sensor.

CO

sensor

For CO

measurement, the Tracer ZN521 requires a CO

sensor with a 4–

20 mA output, where 4 mA = 0 ppm and 20 mA = 2000 ppm.

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Chapter 1 Overview and specifications

6 CNT-SVX07C-EN

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Chapter 2

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 acpower wires.

For application-specific wiring information and diagrams, see Chapter 4,

“Input/output functions and wiring for typical applications”

AC-power wiring



WARNING

HAZARDOUS VOLTAGE!

Before making line voltage electrical connections, lock open the supplypower disconnect switch. Failure to do so may cause death or serious injury.



CAUTION

Make sure that the 24 Vac transformer is properly grounded. Failure to do so may result in damage to equipment and/or personal injury.

Chapter 2 General wiring information

CAUTION

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 Figure 3).

Figure 3. Connecting ac-power wires to the controller

24 Vac transformer

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 Vac). The transformer must be sized to provide adequate power to both the Tracer ZN521 zone controller (14 VA) and its associated output devices, including relays and actuators, to a maximum of 12 VA per output utilized.

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Communication-link wiring and addressing

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 00-01-64-1C-2B-00.

Chapter 2 General wiring information

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Chapter 3

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

Chapter 3 Mounting the controller

Mounting recommendations

Mounting recommendations are as follows:

CAUTION

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-SVX07C-EN

Chapter 4

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 sup-

ported by the Tracer ZN521 zone controller are shown in Table 2.

Table 2. Typical applications for the Tracer ZN521 zone controller

Application

2-pipe hydronic cooling only

2-pipe hydronic heating only

2-pipe changeover

2-pipe steam only

4-pipe hydronic heating and cooling

4-pipe changeover

4-pipe steam/chilled water

Electric heat only (single- and two-stage)

DX/hydronic heating

DX/steam heating

DX cooling only x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x

× x

Figures 7 through 17 (pages 23 through 33) show typical wiring diagrams

that include all required and all optional components for typical applications.

CNT-SVX07C-EN 13

Chapter 4 Input/output functions and wiring for typical applications

Binary inputs

The Tracer ZN521 controller includes four binary inputs. Each binary input associates an input signal of 0 Vac with open contacts and 24 Vac with closed contacts. You can use the Rover service 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.

Table 3 gives the function of each binary input.

Table 3. Binary inputs

Binary input terminal label

BI1

BI2

BI3

BI4

Function

Low-coil-temperature detection

Condensate overflow

Occupancy or generic binary input

Fan status

Each function is explained in the following paragraphs. For an explanation of the diagnostics generated by each binary input, see “Diagnostics” on page 58. For more information about how the controller operates, see

Chapter 5, “Sequence of operations”

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-coil-temperature 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.

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Binary inputs

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 “Occupancy modes” on page 36.)

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 “Fan status” on page 49.)

Chapter 4 Input/output functions and wiring for typical applications

Analog inputs

The Tracer ZN521 controller includes seven analog inputs. Table 4

describes their functions. Each function is explained in the following paragraphs. For an explanation of the diagnostics generated by each analog input, see “Diagnostics” on page 58. For more information about how

the controller operates, see Chapter 5, “Sequence of operations”

Table 4. Analog inputs

Analog input terminal label

GND

SET

FAN

GND

AI1

AI2

AI3

AI4

Function

Zone temperature

Zone sensor common ground

Local setpoint

Fan mode input

Auxiliary ground

Entering water temperature

Discharge air temperature

Outdoor air temperature or generic temperature

Universal 4–20 mA

GND: Ground terminals

Use a GND terminal as the common ground for all zone sensor analog inputs.

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 k

Ω

thermistor in a standard Trane zone 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 hardwired 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 ON and CANCEL buttons.

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Analog inputs

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 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.

Chapter 4 Input/output functions and wiring for typical applications

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 k

Ω

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 k

Ω

thermistor wired to analog input AI3. An 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.

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Analog inputs

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)” on page 45.)

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 (config-

urable using the Rover service tool). (For more information, see “Freeze avoidance” on page 50.)

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 k

Ω

thermistor wired to analog input AI3. The generic temperature input can be used with any Trane 10 k

Ω

thermistor. The thermistor can be 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

Table 5.

Table 5. AI4 configuration options and associated measurement ranges

Configuration Measurement range

Generic 4–20 mA input

measurement

0–100%

(4 mA=0%; 20 mA=100%)

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 hardwired 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

Chapter 4 Input/output functions and wiring for typical applications is established and then is no longer present, the controller generates a

Generic AIP Failure diagnostic.

For the CO

measurement configuration, a 4–20 mA sensor must be hard-

wired to the AI4 terminal as shown in Figure 5. The sensor will transmit

a 0–2000 ppm value 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 CO

Sensor Failure diagnostic.

Figure 5. AI4 terminal wiring: CO

measurement

Tracer ZN521

24 Vac

sensor

(Trane 5010 0828 shown)

24 Vac

GND Signal

For the RH measurement configuration, either a hard-wired 4–20 mA

zone humidity sensor (see Figure 6) 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” on page 47.) If a valid hard-wired or communi-

cated relative humidity value is established and then is no longer present, the controller generates a Humidity Input Failure diagnostic and disables the dehumidification function.

Figure 6. AI4 terminal wiring: RH measurement

Tracer ZN521

RH sensor

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Binary outputs

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. Table 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 damper, close)

• Outdoor air damper, close (return air damper, open)

• Baseboard heat

• Generic

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.

Chapter 4 Input/output functions and wiring for typical applications

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” on page 52.

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

Table 7 shows required controller inputs for minimal proper operation of

all applications.

Table 7. Required controller inputs for proper operation

Function Input source

For more information, see:

24 Vac power

Zone temperature

Terminals: GND, 24 V

“AC-power wiring” on page 7

Terminals: ZN, GND or communicated

“ZN: Zone temperature” on page 16

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

Terminal: AI1 or communicated

Terminals: AI3 or communicated

Terminals: AI4

“AI2: Discharge air temperature” on page 18

“AI1: Entering water temperature” on page 17

“AI3: Outdoor air temperature or generic temperature” on page 18

“AI4: Universal 4–

20 mA” on page 19

Figure 7 on page 23 through Figure 17 on page 33 show typical applica-

tions that include all required and all optional components.

22 CNT-SVX07C-EN

Wiring requirements and options

Figure 7. Two-pipe hydronic-cooling unit

Fan status (closed=on)*

Occupancy (open=occupied)*

Condensate overflow (closed=normal)*

Low-coil-temperature detection

(closed=normal)*

24 Vac

24 V †

Fan, high speed

24 V †

Exhaust (or fan, medium speed)

24 V †

Fan, low speed

24 V †

Cooling valve

24 V †

Electric heat, stage 1 (optional)

24 V †

Electric heat, stage 2 (optional)

24 V †

Outdoor air damper actuator

24 V †

Generic/baseboard heat

CNT-SVX07C-EN

LonTalk

Entering water temperature

Discharge air temperature

AI4 input: See

Figures 5 and 6 on page 20 for

wiring options

LonTalk in out

Outdoor air or generic temperature

* All binary inputs are configurable.

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

Chapter 4 Input/output functions and wiring for typical applications

Figure 8. Two-pipe hydronic-heating unit

24 V †

Fan, high speed

24 V †

Exhaust (or fan, medium speed)

24 V †

Fan, low speed

Fan status (closed=on)*

Occupancy (open=occupied)*

Condensate overflow (closed=normal)*

Low-coil-temperature detection

(closed=normal)*

24 Vac

24 V †

Heating valve

24 V †

Outdoor air damper actuator

24 V †

Generic/baseboard heat

LonTalk

Entering water temperature

Discharge air temperature

AI4 input: See

Figures 5 and 6 on page 20 for

wiring options

Outdoor air or generic temperature

LonTalk in out

* All binary inputs are configurable.

† Connect 24 V to an AC POWER (24V) termi-

CNT-SVX07C-EN

Wiring requirements and options

Low-coil-temperature detection

(closed=normal)*

24 Vac

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

Fan status (closed=on) *

Occupancy (open=occupied)*

Condensate overflow (closed=normal)*

24 V †

Fan, high speed

24 V †

Exhaust (or fan, medium speed)

24 V †

Fan, low speed

24 V †

Heating/cooling changeover valve

24 V †

Electric heat, stage 1 (optional)

24 V †

Electric heat, stage 2 (optional)

24 V †

Outdoor air damper actuator

24 V †

Generic/baseboard heat

CNT-SVX07C-EN

LonTalk

Entering water temperature

Discharge air temperature

AI4 input: See

Figures 5 and 6 on page 20 for

wiring options

Outdoor air or generic temperature

LonTalk in out

* All binary inputs are configurable.

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

Chapter 4 Input/output functions and wiring for typical applications

Figure 10. Four-pipe hydronic heating/cooling unit

24 V †

Fan, high speed

24 V †

Exhaust (or fan, medium speed)

24 V †

Fan, low speed

Fan status (closed=on)*

Occupancy (open=occupied)*

Condensate overflow (closed=normal)*

24 V †

Cooling valve

24 V †

Heating valve

Low-coil-temperature detection

(open=normal)*

24 Vac

24 V †

Outdoor air damper actuator

24 V †

Generic/baseboard heat

LonTalk

Entering water temperature

Discharge air temperature

AI4 input: See

Figures 5 and 6 on page 20 for

wiring options

LonTalk in out

Outdoor air or generic temperature

* All binary inputs are configurable.

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

CNT-SVX07C-EN

Wiring requirements and options

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

24 V †

Fan, high speed

24 V †

Exhaust (or fan, medium speed)

24 V †

Fan, low speed

Fan status (closed=on)*

Occupancy (open=occupied)*

Condensate overflow (closed=normal)*

24 V †

Heating/cooling changeover valve

24 V †

Auxiliary heating valve

Low-coil-temperature detection

(closed=normal)*

24 Vac

24 V †

Outdoor air damper actuator

24 V †

Generic/baseboard heat

CNT-SVX07C-EN

LonTalk

Entering water temperature

Discharge air temperature

AI4 input: See

Figures 5 and 6 on page 20 for

wiring options

LonTalk in out

Outdoor air or generic temperature

* All binary inputs are configurable.

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

Chapter 4 Input/output functions and wiring for typical applications

Figure 12. Two-pipe heating unit with DX cooling

Fan status (closed=on)*

Occupancy (open=occupied)*

Condensate overflow (closed=normal)*

Low-coil-temperature detection

(closed=normal)*

24 Vac

24 V †

Fan, high speed

24 V †

Exhaust (or fan, medium speed)

24 V †

Fan, low speed

24 V †

DX cooling

24 V †

Heating valve

24 V †

Outdoor air damper actuator

24 V †

Generic/baseboard heat

GND 24V 24V 24V

AC POWER

BI1 BI2 BI3

BINARY INPUTS

BI4 1 2 3 4 5 6 7

BINARY OUTPUTS

8 9 10 STATUS

LED

SERVICE

PIN LED

ZONE SENSOR

ZN GND SET FAN GND AI1

ANALOG INPUTS

AI2 AI3 +20 AI4 GND A

COMM5

B A B

COMM5

LED

Cancel

LonTalk

Entering water temperature

Discharge air temperature

AI4 input: See

Figures 5 and 6 on page 20 for

wiring options

LonTalk in out

Outdoor air or generic temperature

* All binary inputs are configurable.

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

CNT-SVX07C-EN

Wiring requirements and options

Figure 13. Electric heat unit with DX cooling

Fan status (closed=on)*

Occupancy (open=occupied)*

Condensate overflow (closed=normal)*

Low-coil-temperature detection

(closed=normal)*

24 Vac

24 V †

Fan, high speed

24 V †

Exhaust

24 V †

DX cooling

24 V †

Electric heat, stage 1 (optional)

24 V †

Electric heat, stage 2 (optional)

24 V †

Outdoor air damper actuator

24 V †

Generic/baseboard heat

GND 24V 24V 24V

AC POWER

BI1 BI2 BI3

BINARY INPUTS

BI4 1 2 3 4 5 6 7

BINARY OUTPUTS

8 9 10 STATUS

LED

CNT-SVX07C-EN

SERVICE

PIN LED

ZONE SENSOR

ZN GND SET FAN GND AI1

ANALOG INPUTS

AI2 AI3 +20 AI4 GND A

COMM5

B A B

COMM5

LED

Cancel

LonTalk

Entering water temperature

Discharge air temperature

AI4 input: See

Figures 5 and 6 on page 20 for

wiring options

LonTalk in out

Outdoor air or generic temperature

* All binary inputs are configurable.

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

Chapter 4 Input/output functions and wiring for typical applications

Figure 14. Electric heat unit

24 V †

Fan, high speed

24 V †

Exhaust

Fan status (closed=on)*

Occupancy (open=occupied)*

Condensate overflow (closed=normal)*

Low-coil-temperature detection

(closed=normal)*

24 Vac

24 V †

Electric heat, stage 1

24 V †

Electric heat, stage 2

24 V †

Outdoor air damper actuator

24 V †

Generic/baseboard heat

LonTalk

Entering water temperature

Discharge air temperature

AI4 input: See

Figures 5 and 6 on page 20 for

wiring options

LonTalk in out

Outdoor air or generic temperature

* All binary inputs are configurable.

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

CNT-SVX07C-EN

Wiring requirements and options

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

Fan status (closed=on)*

Occupancy (open=occupied)*

Condensate overflow (closed=normal)*

Low-coil-temperature detection

(closed=normal)*

24 Vac

24 V †

Fan, high speed

24 V †

Exhaust (or fan, medium speed)

24 V †

Fan, low speed

24 V †

Face & bypass damper actuator

24 V †

Heat isolation valve, open/close

24 V †

Outdoor air damper actuator

24 V †

Generic/baseboard heat

CNT-SVX07C-EN

LonTalk

Entering water temperature

Discharge air temperature

AI4 input: See

Figures 5 and 6 on page 20 for

wiring options

LonTalk in out

Outdoor air or generic temperature

* All binary inputs are configurable.

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

Chapter 4 Input/output functions and wiring for typical applications

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

Fan status (closed=on)*

Occupancy (open=occupied)*

Condensate overflow (closed=normal)*

Low-coil-temperature detection

(closed=normal)*

24 Vac

24 V †

Fan, high speed

24 V †

Exhaust (or fan, medium speed)

24 V †

Fan, low speed

24 V †

Heating/cooling isolation valve, open/close

24 V †

Face-and-bypass damper actuator

24 V †

Outdoor air damper actuator

24 V †

Generic/baseboard heat

LonTalk

Entering water temperature

Discharge air temperature

AI4 input: See

Figures 5 and 6 on page 20 for

wiring options

LonTalk in out

Outdoor air or generic temperature

* All binary inputs are configurable.

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

CNT-SVX07C-EN

Wiring requirements and options

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

24 V †

Fan, high speed

Fan status (closed=on)*

Occupancy (open=occupied)*

Condensate overflow (closed=normal)*

Low-coil-temperature detection

(closed=normal)*

24 Vac

24 V †

Exhaust (or fan, medium speed)

24 V †

Fan, low speed

24 V †

Cooling isolation valve, open/close

24 V †

Face and bypass damper actuator

24 V †

Heating isolation valve, open/close

24 V †

Outdoor air damper actuator

24 V †

Generic/baseboard heat

CNT-SVX07C-EN

LonTalk

Entering water temperature

Discharge air temperature

AI4 input: See

Figures 5 and 6 on page 20 for

wiring options

LonTalk in out

Outdoor air or generic temperature

* All binary inputs are configurable.

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

Chapter 4 Input/output functions and wiring for typical applications

34 CNT-SVX07C-EN

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Chapter 5

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:

The green status indicator LED turns on (see “Interpreting LEDs” on page 56).

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

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

The random-start timer begins (see “Random start” on page 35).

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.)

The random-start timer expires.

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.

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.

Chapter 5 Sequence of operations

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” on page 15)

•

A timed override request from a Trane zone sensor (see “Timed override control” on page 37)

•

A communicated signal from a peer device (see “Peer-to-peer communication” on page 48)

• 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

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 as configured (continuous or cycling). 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 hard-wired 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.

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Timed override control

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 CANCEL 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

CANCEL button cancels 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 will be placed in occupied bypass mode and remain in that mode until either the CANCEL button is pressed on the Trane zone sensor or the occupied bypass time expires.

Chapter 5 Sequence of operations

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 Figure 18). The end devices (outdoor air damper,

valves, etc.) operate in sequence based on the unit heating/cooling capacity (0–100%).

Figure 18. Cascade zone control

Active zone temperature setpoint

Difference

Calculated discharge air temperature setpoint

Difference

Calculated unit heating/cooling capacity

Measured zone temperature

Measured discharge air temperature

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 “Discharge air tempering” on page 39).

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.

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Discharge air tempering

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

Low Limit.

Morning warm-up

The morning warm-up feature is initiated when the controller is in transition from unoccupied to occupied mode and the zone temperature is 3°F

(1.7°C) below the occupied heating setpoint. The fan will be turned on and the outdoor air damper will remain closed. The damper modulates between closed and minimum position when the zone temperature is

2–3°F (1.2–1.7°C) below the active heating setpoint. When the zone temperature reaches the occupied heating setpoint, the controller begins operating in the occupied mode.

Morning cool-down

The morning cool-down feature is initiated when the controller is in transition from unoccupied to occupied and the zone temperature is 3°F

(1.7°C) above the occupied heating setpoint. The fan will be turned on and the outdoor air damper will remain closed. The damper modulates between closed and minimum position when the zone temperature is

2–3°F (1.2–1.7°C) above the active cooling setpoint. When the zone temperature reaches the occupied heating setpoint, the controller begins operating in the occupied mode.

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.

Chapter 5 Sequence of operations

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 informa-

tion, see “Entering water temperature sampling function.”)

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

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Exhaust control 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 (fanspeed 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 set to

AUTO

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

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

Exhaust control

Exhaust control is accomplished by a single-speed exhaust fan or a twoposition 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 Two.

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

• 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).

Chapter 5 Sequence of operations

• 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.

Table 8. Valve control options

Application

Hydronic/steam fan coils and blower coils

Unit ventilators with valve control

Face-and-bypass unit ventilators

Valve operation

The Tracer ZN521 zone controller supports one or two tri-state modulat-

ing or two-position valves, depending on the application (see Table 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” on page 38).

For face-and-bypass applications, one or two isolation valves are controlled.

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.

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Modulating outdoor/return air dampers

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” on page 46.

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 “AI1: Entering water temperature” on page 17

and “Entering water temperature sampling function” on page 40).

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“AI1: Entering water temperature” on page 17

and “Entering water temperature sampling function” on page 40). Elec-

tric 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

Chapter 5 Sequence of operations 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, regard-

less of the occupancy state. See Table 9 and Table 10 for more information

about how the controller determines the position of the modulating outdoor air damper.

Table 9. Modulating outdoor air damper position setpoint determination

Occupancy

BAS-communicated setpoint

Any value

Valid

Fan speed

Any value

Active minimum setpoint

0% (closed)

BAS-communicated

Unoccupied

Occupied

Occupied bypass

Occupied standby

Occupied

Occupied bypass

Occupied standby

Occupied

Occupied bypass

Occupied standby

Invalid

Low

Medium/high

Occupied low fan minimum

Occupied minimum

Occupied standby minimum

Table 10. Relationship between outdoor temperature sensors and damper position

Modulating outdoor air damper position

Outdoor air temperature

Occupied or occupied bypass

Occupied standby Unoccupied

No or invalid outdoor air temperature

Failed outdoor air sensor

Outdoor air temperature present and economizing possible 1

Open to occupied minimum position

Economizing; damper controlled between occupied minimum position and 100%

Open to occupied standby minimum position

Economizing; damper controlled between occupied standby minimum position and

100%

Outdoor air temperature present and economizing not possible 1

Open to occupied minimum position

Open to occupied standby minimum position

For an explanation of the economizing feature, see “Economizing (free cooling)” on page 45.

Closed

Open and economizing during unit operation; otherwise closed

Closed

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Modulating outdoor/return air dampers

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.

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.

Chapter 5 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 “Entering water temperature sampling function” on page 40). For four-pipe

changeover 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-and-bypass damper begins to modulate toward the coil face. The isolation valve closes when capacity returns to

0%.

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.

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Electric heat operation

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.

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.

Chapter 5 Sequence of operations

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)

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Unit protection strategies

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 “Manual (latching) diagnostics” on page 58).

Low-coil-temperature protection

See “BI1: Low-coil-temperature detection” on page 14 and “Smart reset”

above.

Condensate overflow

See “BI2: Condensate overflow” on page 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 belt-driven 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.

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.

Chapter 5 Sequence of operations

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:

• 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 k

Ω

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 Table 16 on page 59 for the effects of this diagnostic on outputs.

50 CNT-SVX07C-EN

Red (service) LED

Service pin button

Chapter 6

Status indicators for operation and communication

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 light-emitting 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 52), which verifies that the controller output devices

are operating properly. It is located on the Tracer ZN521 circuit board as

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

Figure 19. Tracer ZN521 zone controller circuit board

Green (status)

LED

Test button

Neuron ID label

Yellow

(communication)

LED

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Chapter 6 Status indicators for operation and communication

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. Table 11 on page 53 lists the outputs for non-face-and-bypass

unit configurations in the sequence in which they are verified; Table 12 on page 55 lists the outputs for face-and-bypass unit configurations in the

sequence in which they are verified.

The procedure is as follows:

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 Table 14 on page 57) when the Test button is released to indicate that the control-

ler is in manual test mode.

Press the Test button (no more than once per second) to advance

through the test sequence. Table 11 and Table 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.

52 CNT-SVX07C-EN

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CNT-SVX07C-EN

Manual output test

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54 CNT-SVX07C-EN

Manual output test

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 BO

Begins test mode 1

Fan high 2

Fan medium 3

Off

On/High

Off

1) On/Med

2) Off

Off

On/Open

Off

On/Close

Off

On/Close

Off

Fan low 4

Main open,

DX on

Main close,

DX off, aux open

Aux open,

EH1 on, exhaust fan 5

Aux close, damper open

Outdoor air damper close

Generic/ baseboard heat energized 6

Off

On/High

Off

1) Off

2) On

Off

On/Low

Off

On/Open

Off

On/Open

Off

On/Open

Off

On/Close

Off

On/Open

Off

On/Close

Off

11: Exit 5

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 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 en 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

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

CNT-SVX07C-EN 55

Chapter 6 Status indicators for operation and communication

Service pin button

The Service pin button is located as shown in Figure 19 on page 51. 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-SVX01A-EN)

• Make the green (status) LED “wink” to verify that the controller is

communicating on the link (see Table 14 on page 57 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 51) indicates whether the controller is capable of operating normally

(see Table 13).

Table 13. Red LED: Service indicator

LED activity Explanation

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 operating normally.

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

The controller is not executing the application software because the network connections and addressing have been removed.

Restore the controller to normal operation using the Rover service tool. Refer to

EMTX-SVX01A-EN for more information.

56 CNT-SVX07C-EN

CNT-SVX07C-EN

Interpreting LEDs

The green (status) LED on the Tracer ZN521 controller (see Figure 19 on page 51) indicates whether the controller has power applied to it and if

the controller is in manual test mode (see Table 14).

Table 14. Green LED: Status indicator

LED activity Explanation

LED is on continuously.

LED blinks (one recurring blink).

LED blinks (blinks twice as a recurring sequence).

LED blinks (1/4 second on,

1/4 second off for 10 seconds).

Power is on (normal operation).

Manual output test mode is being performed 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.

LED is off continuously.

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

By sending a request from the Rover service tool, you can request the controller’s green LED to blink (“wink”), a notification that the controller received the signal and is communicating.

The yellow (communications) LED on the Tracer ZN521 controller (see

Figure 19 on page 51) indicate the controller’s communication status (see

Table 15).

Table 15. Yellow LED: Communications indicator

LED activity

LED is off continuously

LED blinks.

LED is on continuously.

Explanation

The controller is not detecting any communication (normal for standalone applications).

The controller detects communication (normal for communicating applications, including data sharing).

Problem with communication link wiring (possible need for termination resistor), or controller failure (caused by power surge, lightning strike, etc.)

Chapter 6 Status indicators for operation and communication

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.

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 problem that generated the mes-

sage. For help with diagnosing a problem, see Chapter 7, “Troubleshooting”.

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 Installation/Operation/and Programming guide) .

• Through a building automation system (see product literature)

•

By initiating a manual output test at the controller (see “Manual output test” on page 52)

• By cycling power to the controller. When the 24 Vac power to the controller is cycled off and then on again, a power-up sequence occurs.

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

58 CNT-SVX07C-EN

Diagnostics

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

for “Manual (latching) diagnostics.”

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

Table 16 The tables present 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

Maintenance Required

Condensate Overflow

Low Coil Temp Detection

Low Airflow—Fan Failure

Probable cause Consequences

Diagnostic type

Informational Fan run hours exceed the time set to indicate filter change

The drain pan is full of water

The leaving fluid temperature may be close to freezing

The fan drive belt, contactor, or motor has failed.

Fan unaffected

Valves unaffected

Electric heat unaffected

Face and bypass damper unaffected

Fan off

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

Manual

Smart reset/

Manual

CNT-SVX07C-EN 59

Chapter 6 Status indicators for operation and communication

Table 16. Diagnostics (Continued)

Diagnostic Probable cause Consequences

Diagnostic type

Automatic Space Temperature Failure

Entering Water Temp Failure

Discharge Air Temp Limit

Discharge Air Temp Failure

Outdoor Air Temp Failure

Humidity Input Failure

Sensor Failure

Invalid or missing value for zone temperature

Discharge air temperature has fallen below the

Discharge Air Temperature Low Limit

Invalid or missing value for discharge air temperature

Invalid or missing value for outdoor air temperature

Invalid or missing value for relative humidity

Invalid or missing value for CO

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

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

Fan unaffected

Valves unaffected

Outdoor air damper unaffected

Face and bypass damper unaffected

DX cooling/electric heat unaffected

Baseboard heat unaffected

Automatic

Informational

60 CNT-SVX07C-EN

Diagnostics

Table 16. Diagnostics (Continued)

Diagnostic Probable cause Consequences

Diagnostic type

Informational Generic AIP Failure

Local Fan Mode Failure

Local Setpoint Failure

Generic Temperature Failure

Invalid Unit Configuration

Normal

Invalid or missing value for generic analog input

Invalid or missing fanspeed switch (reverts to default fan speed)

Invalid or missing value for zone temperature setpoint (reverts to default setpoint)

Invalid or missing generic temperature value

Software is configured improperly

On start-up

Fan unaffected

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 unaffected

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

Fan unaffected

Valves unaffected

Electric heat unaffected

Compressors unaffected

Damper unaffected

Automatic

Informational

Manual

Automatic

CNT-SVX07C-EN 61

Chapter 6 Status indicators for operation and communication

62 CNT-SVX07C-EN

Chapter 7

Troubleshooting

Use Table 17 through Table 22 to assist you in diagnosing any of the fol-

lowing operational problems that you might encounter with the Tracer

ZN521 zone controller:

•

Fan does not energize (Table 17)

•

Valves remain closed (Table 18 on page 64)

•

Valves remain open (Table 19 on page 65)

•

Compressors are not running (Table 20 on page 65)

•

Electric heat does not energize (Table 20 on page 65)

•

An outdoor air damper stays closed (Table 21 on page 66)

•

An outdoor air damper stays open (Table 22 on page 66)

Table 17. Fan does not energize

Probable cause Explanation

Unit wiring

Failed end device

Normal operation

The wiring between the controller outputs and the fan relays and contacts must be present and correct for normal fan operation. Refer to applicable wiring diagram.

The fan motor and relay must be checked to ensure proper 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 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.

Diagnostic present

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.

Unit configuration

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

Table 16 on page 59.

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 fans may not work correctly.

Manual output test

Random start observed

The controller includes a manual output test sequence you can use to verify output operation and associated output wiring. However, based on the current step in the test

sequence, the unit fan may not be on. Refer to the “Manual output test” on page 52.

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.

CNT-SVX07C-EN 63

Chapter 7 Troubleshooting

Table 17. Fan does not energize (Continued)

Probable cause Explanation

Cycling fan operation/ continuous

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.

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

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

Requested mode off You can communicate a desired operating mode (such as off, heat, and cool) to the controller. If off is communicated to the controller, the unit controls the fan off. There is no heating or cooling.

Table 18. Valves remain closed

Probable cause Explanation

Unit wiring

Failed end device

No power to the controller

Valve configuration

The wiring between the controller outputs and the valve(s) must be present and correct for normal valve operation. Refer to applicable wiring diagram.

The valves must be checked to ensure proper operation.

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 the green LED is off continuously, the controller does not have sufficient power or has failed.

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

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

Table 16 on page 59.

Normal operation

Unit configuration

Manual output test

Random start observed

Requested mode off

The controller opens and closes the valves to meet the unit 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, the valves may not work correctly.

The controller includes a manual output test sequence you can use to verify output operation 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” on page 52.

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.

You can communicate a desired operating mode (such as off, heat, and cool) to the controller. If off is communicated to the controller, the unit controls the fan off. There is no heating or cooling.

Entering water temperature sampling logic

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” on page 17.)

Make sure the valves are correctly configured, using the Rover service tool, as normally open or normally closed as dictated by the application.

64 CNT-SVX07C-EN

Troubleshooting

Table 19. Valves remain open

Probable cause

Unit wiring

Failed end device

Normal operation

Manual output test

Diagnostic present

Unit configuration

Entering water temperature sampling logic

Valve configuration

Freeze avoidance

Explanation

The wiring between the controller outputs and the valve(s) must be present and correct for normal valve operation. Refer to applicable wiring diagram.

The valves must be checked to ensure proper operations.

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

The controller includes a manual output test sequence you can use to verify output operation 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” on page 52.

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

Table 16 on page 59.

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” on page 17.)

Make sure the valves are correctly configured, using the Rover service tool, as normally open or normally closed as dictated by the application.

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

Table 20. DX or electric heat does not energize

Probable cause

Unit wiring

Failed end device

No power to the controller

Diagnostic present

Normal operation

Unit configuration

Manual output test

Explanation

The wiring between the controller outputs and the end devices must be present and correct for normal operation. Refer to applicable wiring diagram.

Check the control contactors or the electric heat element, including any auxiliary safety 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.

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

diagnostics, see Table 16 on page 59.

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

The controller includes a manual output test sequence you can use to verify output operation 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” on page 52.

CNT-SVX07C-EN 65

Chapter 7 Troubleshooting

Table 20. DX or electric heat does not energize (Continued)

Probable cause

Requested mode off

Freeze avoidance

Explanation

You can communicate a desired operating mode (such as off, heat, and cool) to the controller. If off is communicated to the controller, the unit shuts off the compressor or electric heat.

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

Unit wiring

Failed end device

No power to the controller

Diagnostic present

Normal operation

Unit configuration

Manual output test

Warm-up and cooldown sequence

Requested mode off

Explanation

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.

Check damper actuator to ensure proper operation.

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.

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

diagnostics, see Table 16 on page 59.

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.

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.

The controller includes a manual output test sequence you can use to verify output operation 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” on page 52.

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.

You can communicate a desired operating mode (such as off, heat, or cool) to the controller. If off is communicated to the controller, the unit closes the outdoor air damper.

Table 22. Outdoor air damper remains open

Probable cause

Unit wiring

Failed end device

Explanation

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.

Check damper actuator to ensure proper operation.

66 CNT-SVX07C-EN

Troubleshooting

Table 22. Outdoor air damper remains open (Continued)

Probable cause

Normal operation

Unit configuration

Manual output test

Explanation

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. (See “Modulating outdoor/return air dampers” on page 43.

The controller includes a manual output test sequence you can use to verify output operation 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” on page 52.

CNT-SVX07C-EN 67

Chapter 7 Troubleshooting

68 CNT-SVX07C-EN

CNT-SVX07C-EN

Index

Numerics

24 Vac wiring, 7

A

AC-power wiring, 7

Actuators

Damper, 5, 46

Valve, 4

Additional application-dependent components, 4–5

Addressing

LonTalk communication, 9

Neuron IDs, 9

Agency listing/compliance, 3

Analog inputs, 16–20

AI1 (Entering water temperature),

AI2 (Discharge air temperature), 18

AI3 (Outdoor air temperature), 18

AI3 configuration options, 18

AI4 (Universal 4–20 mA), 19

AI4 configuration options, 19

AI4 configured for CO2 measurement, 20

AI4 configured for RH measurement, 20

AI4 generic configuration, 19

FAN (Fan mode input), 17

Generic temperature, 18

SET (Local setpoint), 17

ZN (Zone temperature), 16

Applications, 1, 13–34

Applications table, 13

ASHRAE Cycle 1

Agency listing/compliance, 4

Operation, 45

ASHRAE Cycle 2

Agency listing/compliance, 4

Operation, 45

B

BAS communication, 1, 9

Baseboard heat

Operation, 47

Supported application, 21

Binary inputs, 14–15

BI1 (Low-coil-temperature detection), 14

BI2 (Condensate overflow), 14

BI3 (Occupancy or generic), 15

BI3 configuration options, 15

BI4 (Fan status), 15

Switching devices, 4

Binary outputs, 21–22

Generic, 21

Manual output test, 52

Output devices, 4

Overriding, 22

Table of supported options, 21

Blower coils, 1, 21

Building automation system communication, 1, 9

C

CE,

see Agency listing/compliance

Circuit board, 51

Clearances, 2

Clearing diagnostics, 58

CO2

Measurement input, 20

Sensor, 5, 20

Sensor failure diagnostic, 60

Condensate overflow

Diagnostic, 59

Input, 14

Switch, 4, 14

Configuration options

AI3 (Outdoor air temperature or generic), 18

AI4 (Generic, CO2 measurement, or

RH measurement), 19

BI3 (Occupancy or generic), 15

DX cooling, 1

Index

Electric heat, 1

Face-and-bypass dampers, 1

Outdoor/return air dampers, 1

Rover service tool, 1

Tri-state modulating dampers, 1

Tri-state modulating valves, 1

Two-position valves, 1

Current-sensing switches, 4

D

Dampers

Actuators, 5

Exhaust, 41

Face-and-bypass, 1, 21, 46

Modulating outdoor/return air,

43, 46

Outdoor/return air, 1, 21, 41, 43

Supported applications, 1, 21

Tri-state modulating, 1

Two-position control, 46

Data sharing, 48

Dehumidification, 47

Device addressing for BAS communication, 9

Diagnosing operational problems,

63–67

Diagnostics

Automatic, 58

Clearing, 58

CO2 Sensor Failure, 60

Condensate Overflow, 59

Discharge Air Temp Failure, 60

Discharge Air Temp Limit, 60

Entering Water Temp Failure, 60

Freeze protection, 60

Generic AIP Failure, 61

Generic Temperature Failure, 61

Humidity Input Failure, 60

Informational, 59

Invalid Unit Configuration, 61

Latching, 58

Local Fan Mode Failure, 61

Local Setpoint Failure, 61

Low Coil Temp Detection, 59

Maintenance (filter change), 59

Manual, 58

Nonlatching, 58

Normal, 61

Outdoor Air Temp Failure, 60

Smart reset, 59

Table, 59

Types, 58

Zone Temp Failure, 59

Dimensional diagram, 3

Dimensions, 2

Discharge air temperature

Failure diagnostic, 60

Low limit diagnostic, 60

Discharge air temperature input, 18

Discharge air temperature low limit,

Discharge air tempering, 39

DX cooling

Operation, 46

Supported application, 21

Troubleshooting, 65

E

Economizing, 19, 45

Electric heat

Operation, 47

Supported application, 21

Troubleshooting, 65

Entering water temperature

Diagnostic, 60

Input, 17

Sampling function, 40

Equipment supported, 1, 13, 21

Exhaust control, 41

F

Fan

Fan status

Filter-maintenance timer, 50

Four-pipe operation, 43

Free cooling,

see Economizing

Freeze avoidance, 19, 50

Freeze protection, 50

Freeze-protection switch, 4, 14

G

Generic

Binary input, 15

Binary output, 59

Temperature input, 18

Generic AIP failure diagnostic, 61

Generic binary input, 15

Generic binary output, 21

Generic temperature failure diagnostic, 61

H

Heating or cooling mode, 39

Humidity

Input failure diagnostic, 60

Measurement input, 20

Zone sensor, 20

Hydronic cooling, 21

I

Informational diagnostics, 59

Input/output functions, 13–34

Input/output terminal wiring, 7

Invalid unit configuration diagnostic, 61

Isolation valve operation, 46

L

LEDs

General, 51

Interpreting green (status), 57

Interpreting red (service), 56

Interpreting yellow

(communications), 57

Location, 51

Local fan mode input failure diagnostic, 61

Local setpoint failure diagnostic, 61

Local setpoint input, 17

LonTalk communication

Description, 1

Termination resistors, 9

Wiring and addressing, 9

LonTalk protocol, see

LonTalk communication

40 CNT-SVX07C-EN

Low-coil-temperature detection

Diagnostic, 14, 59

Input, 14

M

Manual output test, 52

Modulating outdoor/return air dampers, 43

Modulating valves

Calibration, 42

Operation, 42

Morning cool-down, 39

Mounting

Operating environment, 11

Procedures, 12

N

National Electrical Code, 7, 8, 9

Neuron IDs

Description, 9

Location of label, 51

O

Occupancy

Operating environment, 11

Outdoor air damper

Troubleshooting, 66

Outdoor air temperature

Failure diagnostic, 60

Input, 18

Outdoor air temperature input, 18

Outdoor/return air dampers, 43

Output devices, 4

Index

Overriding binary outputs, 22

General, 52

P

Peer-to-peer communication, 48

Power transformers, 4, 7

Power wiring, 7

Power-up sequence, 35

Product description, 1

Protection strategies, see

Unit protection strategies

R

Random start, 35

Rover service tool

Adding a device, 56

Configuring the controller, 1

Identifying a device, 56

User guide, 1

Verifying LonTalk communication, 56

Verifying PCMCIA communications, 56

S

Sensor

Humidity, 47

Sensors

Application-specific, 19

CO2, 5, 20

Table of options, 5

Water and duct temperature, 4

Zone humidity, 5, 20

Zone temperature, 4

Sequence of operations, 35–50

Discharge air temperature low limit, 50

Face-and-bypass damper, 46

Fan off delay, 49

Fan operation, 40

Fan status, 49

Filter-maintenance timer, 50

Four-pipe operation, 43

Freeze avoidance, 50

Freeze protection, 50

Heating/cooling mode, 39

Isolation valve, 46

Modulating-valve calibration, 42

Modulating-valve operation, 42

Morning cool-down, 39

Morning warm-up, 39

Occupancy modes, 36

Outdoor/return air, 43

Peer-to-peer communication, 48

Power-up sequence, 35

Random start, 35

Smart reset, 49

Timed override control, 37

Two-pipe operation, 43

Two-position damper control,

Two-position valve operation,

Unit protection strategies, 48

Valves, 42

Zone temperature control, 38

Service pin button, 51, 56

Smart reset

Diagnostic, 49, 59

Unit protection, 49

Specifications

AC power wiring, 7

Agency listing/compliance, 3

Clearances, 2

Dimensional diagram, 3

Dimensions, 2

Input/output terminal wiring, 7

LonTalk communication wiring and addressing, 9

Storage environment, 2

Transformers, 8

Status indicators for operation and communication

Diagnostics, 58

General, 51

Green (status) LEDs, 57

LEDs, 51

Manual output test, 52

Red (service) LEDs, 56

Service pin button, 56

Test button, 51

Yellow (communication) LEDs,

Storage environment, 2

CNT-SVX07C-EN 41

Index

Switching devices

Condensate overflow, 4, 14

Current sensing, 4

Fan status, 4

Freeze protection, 4, 14

Low-coil-temperature, 4

Occupancy, 4, 15

T

Temperature sensors

Table of options, 5

Water and duct, 4

Zone, 4

Termination resistors, 9

Test button, 51–52

Timeclock, 15

Timed override control, 37

Transformers, 4, 7, 8

Troubleshooting

DX cooling, 65

Electric heat failure, 65

Fans, 63

Outdoor air damper, 66

Valves, 64

Two-pipe operation, 43

Two-position damper control, 46

Two-position valve operation, 43

Types of diagnostics, 58

U

UL,

see Agency listing/compliance

Unit protection strategies

Condensate overflow, 49

Discharge air temperature low limit, 50

Fan off delay, 49

Fan status, 49

Filter-maintenance timer, 50

Freeze avoidance, 50

Freeze protection, 50

Low-coil-temperature protection, 49

Smart reset, 49

Unit ventilators, 1, 21

Universal 4–20 mA, 19

V

Valves

Actuators, 4

Calibration of modulating, 42

Four-pipe operation, 43

General operation, 42

Isolation-valve operation, 43

Operation of modulating, 42

Operation of two-position, 43

Supported applications, 1, 21,

Tri-state modulating, 1, 21, 42

Troubleshooting, 64

Two-pipe operation, 43

Two-position, 1, 21

W

Water and duct temperature sensors, 4

Wiring

BAS communication, 9

Compliance with National

Electrical Code, 7, 8, 9

General, 7–9

Input/output terminals, 7

LonTalk communication, 9

Minimum requirements, 22

Requirements and options,

22–34

Wiring diagrams, 22–34

Electric heat unit, 30

Electric heat unit with DX cooling, 29

Four-pipe heating/cooling unit with auto changeover, 27

Four-pipe heating/cooling unit with face-and-bypass damper,

Four-pipe hydronic heating/ cooling unit, 26

Two-pipe heating unit with DX cooling, 28

Two-pipe heating/cooling unit with face-and-bypass damper,

Two-pipe hydronic heating/ cooling unit with auto changeover, 25

Two-pipe hydronic-cooling unit,

Two-pipe hydronic-heating unit,

Z

Zone humidity

Sensor, 5

Zone temperature

Input, 16

Sensors, 4

Zone temperature control, 38

Zone temperature failure diagnostic, 59

42 CNT-SVX07C-EN

Trane

A business of American Standard Companies www.trane.com

For more information contact your local Trane office or e-mail us at [email protected]

Literature Order Number CNT-SVX07C-EN

File Number

Supersedes

Stocking Location

SV-ES-BAS-CNT-SVX-07C-EN 0405

CNT-SVX07B-EN October 2001

Inland

Trane has a policy of continuous product and product data improvement and reserves the right to change design and specifications without notice. Only qualified technicians should perform the installation and servicing of equipment referred to in this publication.

Key features

Direct-digital zone temperature control
LonTalk communication for BAS integration
Control of valves, dampers, DX cooling, and electric heat
Supports fan coils, unit ventilators, and blower coils
Multiple occupancy modes for energy saving

Frequently asked questions

It controls tri-state modulating or two-position valves and tri-state modulating outdoor/return air, and face-and-bypass dampers.

It uses the LonTalk communication protocol.

It supports Trane 10 kΩ thermistors for temperature and 4-20 mA sensors for humidity and CO2.

Yes, it can operate as a standalone device or as part of a building automation system.