trane_ZN524_1209

Engineering Bulletin
Tracer® ZN524
Unit Controller for water-source heat pumps
December 2009
WSHP-PRB002-EN
Introduction
General
The TracerTM ZN524 water-source heat pump unit controller is a microprocessor-based direct
digital controller that controls a range of water source heat pump equipment including:
•
high-efficiency horizontal and vertical units;
•
premuim-horizontal and vertical units; and
•
console water source heat pumps.
The Tracer ZN524 is designed to provide accurate and reliable zone temperature control through
the use of
pre-engineered control algorithms. Based on the unit type, the controller is a factory installed and
commissioned, resulting in a highly integrated product. Factory commissioning helps to ensure
the highest level of quality and customer satisfaction.
Applications
The ZN524 unit controller may be applied as part of a Trane Tracer Summit® system, as part of a
Trane Tracer Loop controller small building system, a stand-alone device, or as an interoperable
controller. In addition, the unit controller may be applied in a peer-to-peer communication
environment, where data can be exchanged between similar controllers without requiring a master
controller.
Inputs/Outputs
The Tracer ZN524 unit controller is factory configured to control the unit fan, reversing valve, one
or two compressors, and various other end-devices and components. The controller utilizes space
temperature and setpoint inputs; fan mode switch input and entering water temperature to
condition the space. Other optional inputs include condensate overflow, and occupancy.
© 2009 Trane All rights reserved
WSHP-PRB002-EN
Features and Benefits
Factory Installed and Commissioned Controls
All Trane controls are factory-commissioned and installed. The
ZN524 control board, sensors, power transformer, required wiring,
and actuators (when applicable) are installed as part of the normal
construction of the unit.
Upon completion, each unit receives testing via an automated
download/test stand. The computer downloads the proper unit
configuration and location ID and proceeds to test the unit both
mechanically and electrically. The unit must pass all phases of
testing before the automated tester allows the unit to be shipped.
This helps to ensure a high quality product is delivered and
installation time is reduced.
Occupied/Unoccupied
Note: Occupied and unoccupied modes are typically coordinated
by the Trane Tracer Summit or Tracer Loop Controller
The ZN524 unit controller is factory programmed with a set of occupied, occupied standby, and
unoccupied setpoints. During unoccupied conditions, when larger space temperature swings can
be tolerated, the controller significantly reduces unit run-time, saving operating expense.
The controller has a binary input that is configured to be either an input for switching between
occupied and
unoccupied modes or as a generic input. This feature allows the controller to function as a standalone controller, or allows the unit to be put into an occupied standby mode when used with an
occupancy sensor in a building automation system application.
The controller can accept both hardwired and communicating occupancy inputs. This gives the
user ultimate application flexibility for localized or system-wide time-of-day scheduling.
Timed Override
The controller includes a timed override function for after- hours operation. This allows the user
to request unit operation by the touch of a button on the unit’s space temperature sensor.
Additionally, the user can push the cancel button at any time during the override command to place
the unit back into unoccupied mode.
Random Start
The controller inhibits fan and compressor operation for a random period of time at power-up and
on the transition to the occupied mode. This avoids a possible system power surge that may occur
when multiple units start at the same time.
High and Low Pressure Protection
The controller has built-in refrigerant high and low pressure protection capabilities. These safeties
prevent the unit from operating with high/low refrigeration pressure levels that may occur under
abnormal system conditions.
Compressor Minimum Timers
All unit compressors are subjected to minimum on and off timers to prevent short cycling and
therefore maximize compressor life.
Condensate Overflow
When the condensation reaches a trip point in the drain pan, the condensate overflow switch
disables unit operation. This feature prevents water damage to the building.
WSHP-PRB002-EN
3
Features and Benefits
Fan Status
Tracer ZN524 unit controllers provide two methods of monitoring fan status. The first method
monitors the fan output status through the Tracer ZN524 unit controller. This method is not
considered positive proof of airflow, but is typically acceptable on direct drive fan applications.
Tracer ZN524 unit controller also has the ability to accept a binary input from a fan proof switch for
belt driven applications or when proof of flow is required by the customer. When fan operation is
expected by the controller, but not confirmed by the proof switch, unit operation is disabled if the
unit is configured as Fan Status with Diagnostic.
If the unit is configured as Fan Status - No Diagnostic, the status of the fan proof switch will be
passed to the BAS system and does not have any affect on the operation of the unit.
Filter MaintenanceControls
Filter maintenance status for the Tracer ZN524 unit controller is based on
the cumulative run hours of the unit fan. An adjustable and re-settable
timer exists in the controller that, when expired, indicates to the user
through Tracer Summit or Rover service tool, that maintenance is
recommended for that unit. The unit controller complies to ASHRAE 6289 Filtration Section.
Active Dehumidification
The Tracer ZN524 unit controller supports active dehumidification
through the use of a reheat coil and humidity sensor.
This feature allows the user to keep space RH levels within ASHRAE 6289 guidelines to provide comfort as well as minimizing the risk of
microbial growth and damage to the building or its furnishings.
Interoperability
Trane has lead the industry with BACnet interoperability and is now expanding the realm of
interoperable solutions by offering LonMark certified unit controllers. The Tracer ZN524 controller
is certified to the LonMark Space Comfort Controller (SCC) profile. This allows the ZN524 to be used
as a unit controller on other control systems that support LonTalk and the SCC profile (See Table
1, pg. 7). Building owners have more choices and, design engineers have more flexibility to meet
the challenges of building automation.
Waterside economizer
The Tracer ZN524 unit controller supports a two position waterside economizer through the use of
an economizer coil. This feature can help comply with ASHRAE 90.1 guidelines and allows the user
to reduce energy consumption.
Electric/Boilerless Heat
The Tracer ZN524 unit controller supports two types of electric heat, Main heat and Boilerless.
When used as a main heat source the electric heat can operate concurrently with compressor heat
or as the only source of heat. When
configured for boilerless, the electric heat only operates when compressor heat has been disabled,
typically based on entering water temperature.
Manual Output Test
A manual output test function is included to assist in the installation and trouble shooting
processes. This function allows the user to temporarily override normal unit operation and
manually exercise each of the controller’s outputs. This enables the user to quickly verify fan,
reversing valve, compressor, and outdoor air damper operation.
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WSHP-PRB002-EN
Features and Benefits
Generic I/O
Tracer ZN524 unit controller comes equipped with three generic points for use with a Tracer
Summit system:
•
Binary Input (shared with occupancy)
•
Binary Output
•
Analog Input (4-20mA shared with humidity sensor and often used with an optional carbon
dioxide sensor)
The two generic inputs are only for passing information to the BAS system. They do not have any
affect on the operation of the unit. The generic binary output is controlled from the BAS system and
its state is not affected by unit operation, even under a diagnostic shutdown.
WSHP-PRB002-EN
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Specifications
LonMark Space Comfort Controller Profile
The Tracer ZN524 unit controller conforms to the LonMark Space Comfort Controller Profile. It
provides LonTalk communications via an FTT-10A transceiver.
Typical Zone Sensor
Description
•
Space temperature
•
Setpoint
•
Fan switch (off and auto) timed override
and cancel buttons
•
Communication jack for use with laptop
communication tool
•
Vertical case with Trane logo
Specifications
•
Power
•
Dimensions:
– 18 to 32 VAC (24 VAC, 300mA nominal); 50 or 60 Hz
– Height: 5.25” (133.35 mm)
– Width: 5.50” (140 mm)
– Depth: 2.25” (57 mm)
•
Operating Environment Storage
– 32 to 140°F (0 to 60°C)
– 5 to 95% non-condensing
– -40 to 185°F (-40 to 85°C)
•
Environment
5 to 95% non-condensing
•
Agency Listings System
UL and CUL 916 Energy Management
•
Agency Compliance
– IEC 1000-4-2 (ESD)
– IEC 1000-4-4 (EFT)
– IEC 1000-4-5 (Surge)
– FCC Part 15
– Class A
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WSHP-PRB002-EN
Specifications
Table 1.
Input/Output summary
Type
Description
Condensate Overflow
Occupancy(a)
Fan status(b),(c)
Binary Inputs
Low evaporation temperature
Generic (a),(b)
High/Low pressure protect (Circuit 1)
High/Low pressure protect (Circuit 2)
Fan
Reversing Valve
Electric heat(a),(c)
Reheat(a),(c)
Compressor(a)
Binary Outputs
Compressor(b)
Isolation valve(a)
Isolation valve(b)
Waterside economizer (2-position)(c)
Outside Air Damper (2-position)
Generic(b)
Entering water temperature(a)
Outside air temperature (a)
Discharge Air
Leaving Water Temperature (Circuit 1)(c)
Analog Inputs
Space temperature
Space temperature setpoint
Fan switch
Relative humidity(a),(c)
Universal (Generic)(a),(b),(c)
(a) Indicates that two or more features can be associated with this
point (Only one may be used).
(b) Indicates Tracer Summit is required.
(c) Indicates optional feature.
Table 2 provides an input/output listing for the Tracer ZN524 unit controller. Table 3, p. 8 provides
the configuration properties for the unit controller. The content of the lists conforms to both the
LonMark Space Comfort Controller Functional Profile 85.00 and the LonMark node object.
Table 2.
WSHP-PRB002-EN
Input/Output listing
Input
SNVT type
Output
SNVT type
nviRequest
SNVT_obj_request
nvoStatus
SNVT_obj_status
nviSpaceTemp(a)
SNVT_temp_p
nvoFileDirectory
SNVT_address
nviSetpoint
SNVT_temp_p
nvoSpaceTemp(a)
SNVT_temp_p
nviSetptOffset
SNVT_temp_p
nvoUnitStatus(a)
SNVT_hvac_status
nviOccSchedule
SNVT_tod_event
nvoEffectSetpt
SNVT_temp_p
nviOccManCmd
SNVT_occupancy
nvoEffectOccup
SNVT_occupancy
nviOccSensor
SNVT_occupancy
nvoHeatCool
SNVT_hvac_mode
nviApplicMode
SNVT_hvac_mode
nvoSetpoint
SNVT_temp_p
7
Specifications
Table 2.
Input/Output listing (continued)
Input
SNVT type
Output
SNVT type
nviHeatCool
SNVT_hvac_mode
nvoDischAirTemp
SNVT_temp_p
nviFanSpeedCmd
SNVT_switch
nvoLoadAbsK
SNVT_power_kilo
nviComprEnable
SNVT_switch
nvoTerminalLoad
SNVT_lev_percent
nviAuxHeatEnable
SNVT_switch
nvoSpaceRH
SNVT_lev_percent
nviEconEnable
SVNT_switch
nvoOutdoorTemp
SNVT_temp_p
nviEmergOverride
SNVT_hvac_emerg
nvoSpaceCO2
SNVT_ppm
nviSourceTemp
SNVT_temp_p
nvoEnterWaterTemp
SNVT_temp_p
nviSpaceRH
SNVT_lev_percent
nvoLeaveWaterTemp
SNVT_temp_p
nviOutdoorTemp
SNVT_temp_p
nvoOADamper
SNVT_lev_percent
nviValveOverride
SNVT_havac overid
(a) Required points under Space Comfort Controller profile. All other points are optional.
Table 3.
Configuration properties
Configuration
property
SNVT type
nciSndHrtBt(a)
SNVT_time_sec
SCPTmaxSendTime (49)
Send heartbeat
nciSetpoints(a)
SNVT_temp_setpt
SCPTsetPnts (60)
Occupancy temperature setpoint
nciUnitType(a)
SNVT_hvac_type
SCPThvacUnitType (169)
Unit type
nciMinOutTm
SNVT_time_sec
SCPTminSendTime (52)
Minimum send time
nciRcvHrtBt
SNVT_time_sec
SCPTmaxRcvTime (48)
Receive heartbeat
SCPT reference
Description
nciLocation
SNVT_str_asc
SCPTlocation (17)
Location label
nciBypassTime
SNVT_time_min
SCPTbypassTime (34)
Local bypass time
nciRHSpaceSetPt
SNVT_lev_percent
SCPThumSetPt (36)
Space RH setpoint
nciManualTime
SNVT_time_min
SCPTmanOvrTime(35)
Manual Override Duration for Water Valve
(a) Required points under Space Comfort Controller profile. All other points are optional.
Literature Order Number
WSHP-PRB002-EN
Date
December 2009
Supersedes
WSHP-PRB002-EN (April 2002)
www.trane.com
For more information, contact your local Trane
8
office or e-mail us at comfort@trane.com
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
WSHP-PRB002-EN
installation and servicing of equipment referred to in this literature.
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