Trane RLC-PRC006-EN User Manual
™
Air-Cooled Series R
Rotary Liquid Chiller
Model RTAC
140 to 500 Tons (60 Hz)
140 to 400 Tons (50 Hz)
Built For the Industrial and Commercial Markets
RLC-PRC006-ENDecember 2003
Introduction
You…
Like its chillers, Trane wants its
relationships with customers to last.
Trane is interested in maintaining long
term, loyal relationships. This
perspective means the point in time that
a customer purchases a chiller is the
beginning of a relationship, not the end.
Your business is important, but your
satisfaction is paramount.
Designed by Customers….
Trane’s RTAC was designed with the end
user’s requirements in mind. Reliability,
sound, efficiency and physical size were
primary design concerns with this latest
generation machine. New technologies
were applied to literally every major
component. The result is an unparalleled
engineering achievement in chiller
design and manufacturing.
What’s New
The RTAC offers the same high reliability
of Trane’s previous air-cooled helical
rotary design coupled with lowered
sound levels, increased energy
efficiency, reduced physical footprint due
to its advanced design, low speed/direct
drive compressor and proven Series R
performance.
Some of the major advantages of the
Model RTAC are:
• Over 99% reliable
• Lower sound levels
• Higher energy efficiency
• Smaller physical footprint
• HFC-134a optimized design
The Series R Model RTAC is an industrial
grade design built for both the industrial
and commercial markets. It is ideal for
schools, hospitals, retailers, office
buildings, Internet service providers and
manufacturing facilities.
Figure 1. Cutaway of RTAC air-cooled chiller
4
1
2
5
3
5
5
6
1. Flooded Style Evaporator
2. Trane Helical-Rotary Compressor
3. Oil Separator
4. Low Sound Condenser Fans
5. Factory Installed and Tested Unit
Controls and Starter
6. Smaller Physical Footprint
© 2003 American Standard Inc. All rights reserved.
RLC-PRC006-EN
Contents
Introduction
Features and Benefits
World Class Energy Efficiency
Simple Installation
Options
Controls
Application Considerations
Model Number Description
General Data
Selection Procedure
Performance Data
Full Load
Part Load
Adjustment Factors
2
4
8
12
17
18
22
23
RLC-PRC006-EN
Electrical Data and Connection
Wire Size
Typical Wiring Diagram
Field Layout
Dimensions
Weights
Mechanical Specifications
37
63
73
77
3
Features and
Benefits
Table 1. RTAC efficiency vs Ashrae 90.1
Tonnage ASHRAE 90.1 Standard Efficiency High Efficiency ASHRAE 90.1 Standard Efficiency High Efficiency
140 9.6 9.7 10.3 10.4 13.2 13.6
155 9.6 9.8 10.4 10.4 13.5 13.9
170 9.6 9.9 10.5 10.4 13.2 13.7
185 9.6 9.7 10.3 10.4 13.1 13.5
200 9.6 9.6 10.1 10.4 12.9 13.3
225 9.6 9.6 10.2 10.4 13.2 13.6
250 9.6 9.6 10.1 10.4 12.8 13.0
275 9.6 9.7 10.4 10.4 13.3 13.8
300 9.6 9.6 10.1 10.4 13.7 13.8
350 9.6 9.6 10.4 10.4 13.2 14.5
400 9.6 9.6 10.0 10.4 13.7 13.9
450 9.6 9.6 n/a 10.4 14.0 n/a
500 9.6 9.6 n/a 10.4 13.9 n/a
COP = EER/3.414.
Efficiencies given for 60 Hz units
Full Load Efficiency (EER*) Part Load Efficiency (EER*)
RTAC - Exceeding the Efficiency Standard
ASHRAE Standard 90.1 and
RTAC World Class Energy
Efficiency…
The importance of energy efficiency
cannot be understated. Fortunately,
ASHRAE has created a guideline
emphasizing its importance.
Nonetheless, energy is often dismissed
as an operational cost over which the
owner has little control. That perception
results in missed opportunities for
energy efficiency, reduced utility bills,
and higher profits. Lower utility bills
directly affect profitability. Every dollar
saved in energy goes directly to the
bottom line. Trane’s RTAC is one way to
maximize your profits.
ASHRAE Standard 90.1 & Executive
Order - New technology applied to the
design, controls, and manufacturing
have created excellent efficiency levels in
the RTAC that are helping to push
industry minimums to new heights. All
Trane air-cooled chillers meet the new
efficiency levels mandated by ASHRAE
Standard 90.1. This new standard
requires higher efficiencies than past
technologies can deliver. The US Federal
Government has adopted standard 90.1
and, in some cases, requires even higher
efficiencies. Federal Executive Order
mandates energy consuming devices
procured must be in the top 25% of their
class. In the case of chillers, that product
standard is ASHRAE 90.1. Trane’s RTAC
meets and exceeds the efficiency
requirements of 90.1, while the high
efficiency RTAC can meet the “stretch
goals” of Executive Order.
Precise Capacity Control. Trane’s
patented unloading system allows the
compressor to modulate infinitely and
exactly match building loads. At the
same time chilled water temperatures
will be maintained within +/- 1/2ºF
[0.28°C] of setpoint. Reciprocating and
screw chillers with stepped capacity
control do well to maintain chilled water
temperatures within 2ºF [1.1°C] of
setpoint. Stepped control also results in
overcooling your space because rarely
does the capacity of the machine match
the building load. The result can be 10%
higher energy bills. Trane’s RTAC
optimizes the part load performance of
your machine for energy efficiency,
precise control for process applications,
and your personal comfort regardless of
the weather outside.
RLC-PRC006-EN4
Features and
Benefits
Figure 2. Cutaway of a compressor
Excellent Reliability…
A buildings environment is expected to
be comfortable. When it is, no one says
a word. If it’s not… that’s a different
story. The same is true with chillers. No
one ever talks about chillers, yet alone
compressors, until they fail, and tenants
are uncomfortable and productivity is
lost. Trane’s helical rotary compressors
have a first year reliability rate of over
99%, which means our chillers stay
running when you need them.
Fewer moving parts. Trane’s helical
rotary compressors have only two major
rotating parts: the male and female rotor.
A reciprocating compressor can have
more than 15 times that number of
critical parts. Multiples of pistons, valves,
crankshafts, and connecting rods in a
reciprocating unit all represent different
failure paths for the compressor. In fact,
reciprocating compressors can easily
have a failure rate four times of a helical
rotor. Combine that with two to three
reciprocating compressors for each
helical rotary compressor on chillers of
equal tonnage, and statistics tell you it’s
a matter of time before you lose a
reciprocating compressor.
Robust components. Helical rotary
compressors are precisely machined
using state of the art processes from
solid metal bar stock. Tolerances are
maintained within a micron or less than
a tenth of the diameter of a human hair.
The resulting compressor is a robust yet
highly sophisticated assembly capable of
ingesting liquid refrigerant without risk
of damage. Contrast this to a
reciprocating compressor, which can be
destroyed by a single slug of liquid.
Condenser coils. Trane’s condenser
coils are manufactured with the same
philosophy as the compressors; they’re
built to last. Even though manufacturing
processes have allowed thinner and
thinner materials in their assembly, with
obvious material and manufacturing
savings, Trane’s coil material did not
change with the RTAC generation of air
cooled chillers. Substantial condenser
fins, that do not require additional
coating in non-corrosive environments,
contribute to the highest reliability
standards for air-cooled chillers in the
industry.
5RLC-PRC006-EN
Features and
Benefits
Superior Control
The Adaptive Control™ microprocessor
system enhances the air-cooled Series R
chiller by providing the very latest chiller
control technology. With the Adaptive
Control microprocessor, unnecessary
service calls and unhappy tenants are
avoided. The unit is designed not to trip
or unnecessarily shut down. Only when
the Tracer
exhausted all possible corrective actions
and the unit is still violating an operating
limit will the chiller shut down. Controls
on other equipment typically shut down
the chiller, usually just when it is needed
the most.
For example:
A typical five-year-old chiller with dirty
coils might trip-out on high pressure
cutout on a 100°F [38°C] day in August. A
hot day is just when comfort cooling is
needed the most. In contrast, the aircooled Series R chiller with an Adaptive
Control microprocessor will stage fans
on, modulate electronic expansion valve,
and modulate slide valve position as it
approaches a high pressure cutout,
thereby keeping the chiller on-line when
you need it the most.
™
chiller controllers have
Simple Installation
• Compact Physical Size. The Trane
Model RTAC chiller averages a 20%
reduction in physical footprint, while
the greatest change is actually 40%
smaller when compared against the
previous design. This improvement
makes the RTAC the smallest air-cooled
chiller in the industry and a prime
candidate for installations that have
space constraints. All physical sizes
were changed without sacrificing the
side clearances needed to supply fresh
airflow without coil starvation.
• Close Spacing Installation. The air-
cooled Series R™ Chiller has the tightest
recommended side clearance in the
industry, four feet for maximum
performance. In situations where
equipment must be installed with less
clearance than recommended, which
frequently occurs in retrofit
applications, restricted airflow is
common. Conventional chillers may
not work at all. However, the air-cooled
Series R chiller with Adaptive Control
microprocessor will make as much
chilled water as possible given the
actual installed conditions, stay on line
during unforeseen abnormal
conditions, and optimize the unit
performance. Consult your Trane sales
engineer for more details.
• Factory Testing Means Trouble-Free
Start-Up. All air-cooled Series R chillers
are given a complete functional test at
the factory. This computer-based test
program completely checks the
sensors, wiring, electrical components,
microprocessor function,
communication capability, expansion
valve performance and fans. In
addition, each compressor is run and
tested to verify capacity and efficiency.
Where applicable, each unit is factory
preset to the customer’s design
conditions; an example would be
leaving liquid temperature setpoint.
The result of this test program is that
the chiller arrives at the job site fully
tested and ready for operation.
• Factory Installed and Tested Controls/
Options Speed Installation. All Series R
chiller options, including main power
supply disconnect, low ambient
control, ambient temperature sensor,
low ambient lockout, communication
interface and ice making controls, are
™
factory installed and tested. Some
manufacturers send accessories in
pieces to be field installed. With Trane,
the customer saves on installation
expense and has assurance that ALL
chiller controls/options have been
tested and will function as intended.
RLC-PRC006-EN6
Features and
High Efficiency/Performance Option
This option provides oversized heat
exchangers for two purposes. One, it
allows the unit to be more energy
efficient. Two, the unit will have
enhanced operation in high ambient
conditions.
Low Temperature Brine
The hardware and software on the unit
are factory set to handle low
temperature brine applications (less than
40°F [4.4°C]).
Ice Making
The unit controls are factory set to
handle ice making for thermal storage
applications.
Tracer Summit Communication
Interface
Permits bi-directional communication to
the Trane Integrated Comfort
LonTalk (LCI-C) Communications
Interface
Provides the LonMark chiller profile
inputs/outputs for use with a generic
building automation system.
Remote Input Options
Permits remote chilled liquid setpoint,
remote current limit setpoint, or both by
accepting a 4-20 mA or 2-10 Vdc analog
signal.
Remote Output Options
Permits alarm relay outputs, ice making
outputs, or both.
Architectural Louvered Panels
Louvered panels cover the complete
condensing coil and service area
beneath the condenser.
Coil Protection
Louvered panels protect the condenser
coils only.
™
system.
Benefits
Access Protection
A coated wire mesh that covers the
access area under the condenser coils.
Wye-Delta Compressor Start Type
This option provides a reduced inrush
starter. Wye-Delta starters are standard
on 200-230 volt machines.
Condenser Corrosion Protection
Copper fins and CompleteCoat are
available on all size units for corrosion
protection. Job site conditions should be
matched with the appropriate condenser
fin materials to inhibit coil corrosion and
ensure extended equipment life. The
CompleteCoat option provides fully
assembled coils with a flexible dip and
bake epoxy coating.
TEAO Condenser Fan Motors
Totally enclosed air-over (TEAO) motors
completely seal the motor windings to
prevent exposure to ambient conditions.
Low Ambient Option
The low ambient option provides special
control logic and variable frequency
drives on the condenser fan circuits to
permit low temperature start-up and
operation down to 0°F [-18°C].
Single/Dual Incoming Power Line
Connection
Single or dual points of termination are
available for incoming power line
connections*. Units with 3-4
compressors must order circuit breakers
with the single point connection option.
*Some restrictions may apply.
Convenience Outlet
Provides a 15 amp, 115 volt (60 Hz)
convenience outlet on the unit.
Remote Evaporator
The remote evaporator option is
available on the RTAC 140-250 ton units.
This option provides a pre-engineered
method of installing the evaporator and
all related components indoors.
Remote evaporator installations allow
the water loop to remain indoors to
prevent freezing, thus eliminating the
addition of glycol to the system and the
resulting performance degradation.
Options
High Ambient Option
The high ambient option consists of
special control logic to permit high
ambient (up to 125°F [51°C]) operation.
This option offers the best performance
when coupled with the high efficiency
performance option.
Non-Fused Power Disconnect Switch
The non-fused molded case disconnect
switch (UL approved) is used to
disconnect the chiller from main power
and comes pre-wired from the factory
with terminal block power connections.
The external operator handle is lockable.
Circuit Breaker
A HACR rated molded case capacity
circuit breaker (UL approved) is
available. The circuit breaker can also be
used to disconnect the chiller from main
power with a through-the-door handle
and comes pre-wired from the factory
with terminal block power connections.
The external operator handle is lockable.
Neoprene Isolators
Isolators provide isolation between
chiller and structure to help eliminate
vibration transmission. Neoprene
isolators are more effective and
recommended over spring isolators.
Flange Kit
Provides a raised-face flange kit that
converts the grooved pipe evaporator
water connections to flange connectors.
7RLC-PRC006-EN
Controls
Standalone Controls
Human Interfaces
The Trane air-cooled Model RTAC chiller
offers two easy-to-use operator interface
panels, the EasyView and the DynaView.
EasyView is a coded display that allows
the user to access the current leaving
water temperature, its setpoint, and any
recent diagnostics.
DynaView is an LCD touchscreen display
that is navigated by file tabs. This is an
advanced interface that allows the user
to access any important information
concerning setpoints, active
temperatures, modes, electrical data,
pressures, and diagnostics.
Adaptive Safety Controls
A centralized microcomputer offers a
higher level of machine protection. Since
the safety controls are smarter, they limit
compressor operation to avoid
compressor or evaporator failures,
thereby minimizing nuisance shutdown.
™
Tracer
Chiller Controls directly senses
the control variables that govern the
operation of the chiller: motor current
draw, evaporator pressure and
condenser pressure. When any one of
these variables approaches a limit
condition where damage may occur to
the unit or shutdown on a safety, Tracer
Chiller Controls takes corrective action to
avoid shutdown and keep the chiller
operating. This happens through
combined actions of compressor slide
valve modulation, electronic expansion
valve modulation and fan staging. Tracer
Chiller Controls optimizes total chiller
power consumption during normal
operating conditions. During abnormal
operating conditions, the
microprocessor will continue to optimize
chiller performance by taking the
corrective action necessary to avoid
shutdown. This keeps cooling capacity
available until the problem can be
solved. Whenever possible, the chiller is
allowed to perform its function; making
Figure C1. DynaView operator interface
Figure C2. EasyView operator interface
chilled water. In addition, microcomputer
controls allow for more types of
protection such as over and under
voltage. Overall, the safety controls help
keep the building or process running and
out of trouble.
Standalone Controls
Interface to standalone units is very
simple; only a remote auto/stop for
scheduling is required for unit operation.
Signals from the chilled water pump
contactor auxiliary or a flow switch are
wired to the chilled waterflow interlock.
Signals from a time clock or some other
remote device are wired to the external
auto/stop input.
Standard Features
• External Auto/Stop — A jobsite
provided contact closure will turn the
unit on and off.
• Chilled Waterflow Interlock — A jobsite
provided contact closure from a chilled
water pump contactor or a flow switch
is required and will allow unit operation
if a load exists. This feature will allow
the unit to run in conjunction with the
pump system.
• External Interlock — A jobsite supplied
contact opening wired to this input will
turn the unit off and require a manual
reset of the unit microcomputer. This
closure is typically triggered by a
jobsite supplied system such as a fire
alarm.
• Chilled Water Pump Control — Unit
controls provide an output to control
the chilled water pump(s). One contact
closure to the chiller is all that is
required to initiate the chilled water
system. Chilled water pump control by
the chiller is a requirement on the AirCooled Series R.
• Chilled Water Temperature Reset —
Reset can be based on return water
temperature or outdoor air
temperature.
RLC-PRC006-EN8
Generic Building Automation
Easy Interface to A Generic Building
Management System
Controlling the air-cooled Series R chiller
with building management systems is
state-of-the-art, yet simple with either the
LonTalk Communications Interface for
Chillers (LCI-C) or Generic Building
Management System Hardwire Points.
What are LonTalk, Echelon, and
LonMark?
LonTalk is a communications protocol
developed by the Echelon Corporation.
The LonMark association develops
control profiles using the LonTalk
communication protocol. LonTalk is a
unit level communications protocol,
unlike BACNet used at the system level.
LonTalk Communications
Interface for Chillers (LCI-C)
LonTalk Communications Interface for
Chillers (LCI-C) provides a generic
automation system with the LonMark
chiller profile inputs/outputs. The inputs/
outputs include both mandatory and
optional network variables. Note:
LonMark network variable names are in
parentheses when different from chiller
naming convention.
Chiller Inputs:
• Chiller Enable/Disable
• Chilled Liquid Setpoint (Cool Setpoint)
• Current Limit Setpoint (Capacity Limit
Input)
• Ice Making (Chiller Mode)
Chiller Enable/Disable
Allows for chiller to be started or
stopped depending on if certain
operating conditions are met.
Chilled Liquid Setpoint
Allows for the external setting
independent of the front panel setpoint
to adjust the leaving water temperature
setpoint.
Current Limit Setpoints
Allows for the external setting
independent of the front panel setpoint
to limit the capacity level of the chiller.
Ice Making
Provides interface with ice making
control systems.
Controls
™
Chiller
System Level
Controller
MP581 Programmable
Controller
MP581
Programmable
Controller
PC Workstation
Air-cooled
Series R
System Controls
Ice Tanks
Boiler
Chiller Outputs:
• On/Off
• Active Setpoint
• Average Percent RLA (Actual Capacity
Level)
• Active Current Limit Setpoint (Capacity
Limit)
• Leaving Chilled Water Temperature
• Entering Chilled Water Temperature
• Alarm Descriptor
• Chiller Status
On/Off
Indicates the current state of the chiller
Active Setpoint
Indicates the current value of the leaving
water temperature setpoint
Average Percent RLA
Provides the current capacity level via
%RLA
Active Current Limit Setpoint
Provides the current capacity level
setpoint via %RLA
Alarm Descriptor
Provides alarm messages based on predetermined criteria
Chiller Status
Indicates the running modes and states
of the chiller, i.e. Running in alarm mode,
chiller enabled, chiller being locally
controlled, etc…
Generic Building Management
System Hardwire Points
GBAS may be achieved via hardware
input/output as well. The input/outputs
are as follows:
Chiller hardwire inputs include:
• Chiller enable/disable
• Circuit enable/disable
• External chilled water setpoint
• External current limit setpoint
• Ice making enable
External Chilled Water Setpoint
Allows the external setting independent
of the front panel setpoint by one of two
means:
a) 2-10 VDC input, or
b) 4-20 mA input
External Current Limit Setpoint
Allows the external setting independent
of the front panel setpoint by one of two
means:
c) 2-10 VDC input, or
b) 4-20 mA input
Chiller hardwire outputs include:
• Compressor running indication
• Alarm indication (Ckt1/Ckt 2)
• Maximum capacity
• Ice making status
Alarm Indication Contacts
The unit provides three single-pole/
double-throw contact closures to
indicate:
a) Compressor on/off status
b) Compressor running at maximum
capacity
c) Failure has occurred (Ckt 1/Ckt 2)
These contact closures may be used to
trigger jobsite supplied alarm lights or
alarm bells.
Ice Making Control
Provides interface with ice making
control systems.
9RLC-PRC006-EN
Trane Integrated Comfort
Modem
Building
Control Unit
Diffuser
Diffuser
PC Workstation
Exhaust Fan
Remote PC Workstation
®
VariTrane
Variable Air Volume
Terminal
Room temperature
sensor
®
VariTrane
Variable Air Volume
Terminal
Room temperature
sensor
Tracer Summit controls — Interface
With The Trane Integrated Comfort
System (ICS)
Trane Chiller Plant Control
The Tracer Summit Chiller Plant Building
Management System with Chiller Plant
Control provides building automation
and energy management functions
through stand-alone control. The Chiller
Plant Control is capable of monitoring
and controlling your entire chiller plant
system.
Application software available:
• Time-of-day scheduling
• Demand limiting
• Chiller sequencing
• Process control language
• Boolean processing
• Zone control
Controls
Notebook
PC Workstation
LAN
Building
Control Unit
Modular Climate Changer
Air Handler
• Reports and logs
• Custom messages
• Run time and maintenance
• Trend log
• PID control loops
And of course, the Trane Chiller Plant
Control can be used on a stand-alone
basis or tied into a complete building
automation system.
When the air-cooled Series R
used in conjunction with a Trane Tracer
Summit system, the unit can be
monitored and controlled from a remote
location. The air-cooled Series R chiller
can be controlled to fit into the overall
building automation strategy by using
time of day scheduling, timed override,
demand limiting, and chiller sequencing.
A building owner can completely
®
Air-cooled Series R
®
Chiller
™
chiller is
System Controls
monitor the air-cooled Series R chiller
from the Tracer system, since all of the
monitoring information indicated on the
unit controller’s microcomputer can be
read off the Tracer system display. In
addition, all the powerful diagnostic
information can be read back at the
Tracer system. Best of all, this powerful
capability comes over a single twisted
pair of wires! Air-cooled Series R chillers
can interface with many different
external control systems, from simple
stand-alone units to ice making systems.
Each unit requires a single-source, threephase power supply and a single-phase
115V/60Hz, [220V/50Hz] power supply.
The added power supply powers the
evaporator heaters.
A single twisted pair of wires tied directly
between the air-cooled Series R
and a Tracer
control, monitoring and diagnostic
capabilities. Control functions include
auto/stop, adjustment of leaving water
temperature setpoint, compressor
operation lockout for kW demand
limiting and control of ice making mode.
The Tracer system reads monitoring
information such as entering and leaving
evaporator water temperatures and
outdoor air temperature. Over 60
individual diagnostic codes can be read
by the Tracer system. In addition, the
Tracer system can provide sequencing
control for up to 25 units on the same
chilled water loop. Pump sequencing
control can be provided from the Tracer
system. Tracer ICS is not available in
conjunction with the remote display or
the external setpoint capability.
Required Options
Tracer Interface
External Trane Devices Required
Tracer Summit
Tracer Chiller Plant Control
Additional Features That May Be Used
Ice Making Control
™
™
Summit system provides
™
, Tracer 100 System or
™
chiller
RLC-PRC006-EN10
Trane Integrated Comfort
Trane Chiller Plant Automation
Trane’s depth of experience in chillers
and controls makes us a well-qualified
choice for automation of chiller plants
using air-cooled Series R
chiller plant control capabilities of the
Trane Tracer Summit
automation system are unequaled in the
industry. Our chiller plant automation
software is fully pre-engineered and
tested. It is a standard software
application, not custom programming
which can prove to be difficult to
support, maintain, and modify.
Energy Efficiency
Trane chiller plant automation
intelligently sequences starting of
chillers to optimize the overall chiller
plant energy efficiency. Individual chillers
are designated to operate as base, peak,
or swing based on capacity and
efficiency. Sophisticated software
automatically determines which chiller
to run in response to current conditions.
The software also automatically rotates
individual chiller operation to equalize
runtime and wear between chillers.
Trane chiller plant automation enables
unique energy-saving strategies. An
example is controlling pumps, and
chillers from the perspective of overall
system energy consumption. The
software intelligently evaluates and
selects the lowest energy consumption
alternative.
®
chillers®. The
®
building
Controls
Keeping Operators Informed
A crucial part of efficiently running a
chiller plant is assuring that the
operations staff is instantly aware of
what is happening in the plant. Graphics
showing schematics of chillers, piping,
pumps, and towers clearly depict the
chiller plant system, enabling building
operators to easily monitor overall
conditions. Status screens display both
current conditions and upcoming
automated control actions to add or
subtract chiller capacity. Series R and
other chillers can be monitored and
controlled from a remote location.
Tracer Summit features standard report
templates listing key operating data for
troubleshooting and verifying
performance. Reports for each type of
Trane chiller and three and six-chiller
systems are also standard. Detailed
reports showing chiller runtimes aid in
planning for preventative maintenance.
Swift Emergency Response
We understand the importance of
maintaining chilled water production
while protecting your chillers from costly
damage. If no water flow is detected to a
chiller’s piping, the start sequence is
aborted to protect the chiller. The next
chiller in the sequence is immediately
started to maintain cooling.
In the event of a problem, the operator
receives an alarm notification and
diagnostic message to aid in quick and
accurate troubleshooting. A snapshot
report showing system status just prior
to an emergency shutdown helps
operators determine the cause. If
emergency conditions justify an
immediate manual shutdown, the
operator can override the automatic
control.
Easy Documentation for Regulatory
Compliance
Comprehensive documentation of
refrigerant management practices is
now a fact of life. Trane chiller plant
automation generates the reports
mandated in ASHRAE Guideline 3.
System Controls
Integrated Comfort™ Capabilities
When integrated with a Tracer Summit
building management system
performing building control, Trane chiller
plant automation coordinates with
Tracer Summit applications to optimize
the total building operation. With this
system option, the full breadth of Trane’s
HVAC and controls experience are
applied to offer solutions to many facility
issues. If your project calls for an
interface to other systems, Tracer
Summit can share data via BACnet
ASHRAE open systems protocol.
Ice Making Systems Controls
Simple and smart control strategies are
another advantage the Model RTAC
chiller offers for ice storage applications.
Trane Tracer
systems can actually anticipate how
much ice needs to be made at night and
operate the system accordingly. The
controls are integrated right into the
chiller. Two wires and preprogrammed
software dramatically reduce field
installation cost and complex
programming.
When the ice making option is ordered,
the air-cooled Series R chiller will have
two operating modes, ice making and
normal daytime cooling. In the ice
making mode, the air-cooled Series R
chiller will operate at full compressor
capacity until the return chilled fluid
temperature entering the evaporator
meets the ice making setpoint. This ice
making setpoint is manually adjusted on
the unit’s microcomputer. Two input
signals are required to the air-cooled
Series R chiller for the ice making option.
The first is an auto/stop signal for
scheduling and the second is required to
switch the unit in between the ice
making mode and normal daytime
operation. The signals are provided by a
remote job site building automation
device such as a time clock or a manual
switch. In addition, the signals may be
provided over the twisted wire pair from
a Tracer system or LonTalk
Communication Interface but will require
the communication boards provided
with the Ice Making Control Option.
™
building management
™
, the
11RLC-PRC006-EN
Application
Considerations
Important
Certain application constraints should be
considered when sizing, selecting and
installing Trane air-cooled Series R
chillers. Unit and system reliability is
often dependent upon proper and
complete compliance with these
considerations. When the application
varies from the guidelines presented, it
should be reviewed with your local
Trane sales engineer.
Unit Sizing
Unit capacities are listed in the
performance data section. Intentionally
over-sizing a unit to assure adequate
capacity is not recommended. Erratic
system operation and excessive
compressor cycling are often a direct
result of an oversized chiller. In addition,
an oversized unit is usually more
expensive to purchase, install, and
operate. If over-sizing is desired,
consider using multiple units.
Water Treatment
Dirt, scale, products of corrosion and
other foreign material will adversely
affect heat transfer between the water
and system components. Foreign matter
in the chilled water system can also
increase pressure drop and
consequently, reduce water flow. Proper
water treatment must be determined
locally, depending on the type of system
and local water characteristics. Neither
salt nor brackish water is recommended
for use in Trane air-cooled Series R
chillers. Use of either will lead to a
shortened life to an indeterminable
degree. The Trane Company encourages
the employment of a reputable water
treatment specialist, familiar with local
water conditions, to assist in this
determination and in the establishment
of a proper water treatment program.
Effect Of Altitude On Capacity
Air-cooled Series R chiller capacities
given in the performance data tables are
for use at sea level. At elevations
substantially above sea level, the
decreased air density will reduce
condenser capacity and, therefore, unit
capacity and efficiency.
Ambient Limitations
Trane air-cooled Series R chillers are
designed for year-round operation over
a range of ambient temperatures. The
Model RTAC chiller will operature as
standard in ambient temperatures of 25
to 115°F [-4 to 46°C]. With the low
ambient option, these units will operate
down to 0°F [-18°C]. If an ambient
temperature as high as 125°F [51°C] is
the basis for design, the high ambient
option will permit the chiller to run
without going into a limiting condition.
For installations in areas with large
ambient differences, the wide ambient
option will allow the chiller to perform
uninhibited from 0 to 125°F [-18 to 51°C].
For operation outside these ranges,
contact the local Trane sales office.
Figure A1. GPM out of range system layout
Water Flow Limits
The minimum and maximum water flow
rates are given in Tables G-1 through
G-4. Evaporator flow rates below the
tabulated values will result in laminar
flow causing freeze-up problems,
scaling, stratification and poor control.
Flow rates exceeding those listed may
result in excessive tube erosion.
Flow Rates out of Range
Many process cooling jobs require flow
rates that cannot be met with the
minimum and maximum published
values for the Model RTAC evaporator. A
simple piping change can alleviate this
problem. For example: A plastic injection
molding process requires 80 gpm
[5.1 l/s] of 50°F [10°C] water and returns
that water at 60°F [15.6°C]. The selected
chiller can operate at these
temperatures, but has a minimum flow
rate of 120 gpm [7.6 l/s]. The system
layout in Figure A1 can satisfy the
process.
Flow Control
Trane requires the chilled water flow
control in conjunction with the AirCooled Series R Chiller to be done by the
chiller. This will allow the chiller to
protect itself in potentially harmful
conditions.
RLC-PRC006-EN12
Application
Considerations
Leaving Water Temperature Limits
Trane air-cooled Series R chillers have
three distinct leaving water categories:
standard, low temperature, and ice
making. The standard leaving solution
temperature range is 40 to 60°F [4.4 to
15.6°C]. Low temperature machines
produce leaving liquid temperatures less
than 40°F [4.4°C]. Since liquid supply
temperature setpoints less than
40°F [4.4°C] result in suction
temperatures at or below the freezing
point of water, a glycol solution is
required for all low temperature
machines. Ice making machines have a
leaving liquid temperature range of 20 to
60°F [-6.7 to 15.6°C]. Ice making controls
include dual setpoint controls and
safeties for ice making and standard
cooling capabilities. Consult your local
Trane sales engineer for applications or
selections involving low temperature or
ice making machines. The maximum
water temperature that can be circulated
through an evaporator when the unit is
not operating is 108°F [42°C].
Leaving Water Temperature out of
Range
Many process cooling jobs require
temperature ranges that cannot be met
with the minimum and maximum
published values for the Model RTAC
evaporator. A simple piping change can
alleviate this problem. For example: A
laboratory load requires 120 gpm
[7.6 l/s] of water entering the process at
85°F [29.4°C] and returning at 95°F
[35°C]. The accuracy required is better
than the cooling tower can give. The
selected chiller has adequate capacity,
but a maximum leaving chilled water
temperature of 60°F [15.6°C].
In Figure A2, both the chiller and process
flow rates are equal. This is not
necessary. For example, if the chiller had
a higher flow rate, there would simply be
more water bypassing and mixing with
warm water.
Supply Water Temperature Drop
The performance data for the Trane aircooled Series R chiller is based on a
chilled water temperature drop of 10°F
Figure A2. Temperature out of range system layout
[5.6°C]. Chilled water temperature drops
from 6 to 18°F [3.3 to 10°C] may be used
as long as minimum and maximum
water temperatures and flow rates are
not violated. Temperature drops outside
this range are beyond the optimum
range for control and may adversely
affect the microcomputer’s ability to
maintain an acceptable supply water
temperature range. Further, temperature
drops of less than 6°F [3.3°C] may result
in inadequate refrigerant superheat.
Sufficient superheat is always a primary
concern in any refrigerant system and is
especially important in a package chiller
where the evaporator is closely coupled
to the compressor. When temperature
drops are less than 6°F [3.3°C], an
evaporator runaround loop may be
required.
Variable Flow in the Evaporator
An attractive chilled water system option
may be a variable primary flow (VPF)
system. VPF systems present building
owners with several cost-saving benefits
that are directly related to the pumps.
The most obvious cost savings result
from eliminating the secondary
distribution pump, which in turn avoids
the expense incurred with the associated
piping connections (material, labor),
electrical service, and variable-frequency
drive. Building owners often cite pump-
related energy savings as the reason that
prompted them to install a VPF system.
With the help of a software analysis tool
such as System Analyzer
can determine whether the anticipated
energy savings justify the use of variable
primary flow in a particular application. It
may also be easier to apply variable
primary flow in an existing chilled-water
plant. Unlike the “decoupled” system
design, the bypass can be positioned at
various points in the chilled-water loop
and an additional pump is unnecessary.
The evaporator on the Model RTAC can
withstand up to 50 percent water flow
reduction as long as this flow is equal to
or above the minimum flow rate
requirements. The microprocessor and
capacity control algorithms are designed
to handle a maximum of 10% change in
water flow rate per minute in order to
maintain ± 0.5°F [0.28°C] leaving
evaporator temperature control. For
applications in which system energy
savings is most important and tight
temperature control is classified as
+/- 2°F [1.1°C], up to 30 percent changes
in flow per minute are possible.
™
or DOE-2, you
13RLC-PRC006-EN
Application
Considerations
Series Chiller Arrangements
Another energy-saving strategy is to
design the system around chillers
arranged in series. The actual savings
possible with such strategies depends
on the application dynamics and should
be researched by consulting your Trane
Systems Solutions Representative and
applying the Trane System Analyzer
program. It is possible to operate a pair
of chillers more efficiently in a series
chiller arrangement than in a parallel
arrangement. It is also possible to
achieve higher entering-to-leaving chiller
differentials, which may, in turn, provide
the opportunity for lower chilled water
design temperature, lower design flow,
and resulting installation and operational
cost savings. The Trance screw
compressor also has excellent
capabilities for “lift,” which affords an
opportunity for savings on the
evaporator water loop.
Figure A3. Typical series chiller arrangement
Series chiller arrangements can be
controlled in several ways. Figure A3
shows a strategy where each chiller is
trying to achieve the system design set
point. If the cooling load is less than 50
percent of the systems capabilities,
either chiller can fulfill the demand. As
system loads increase, the Chiller 2
becomes preferentially loaded as it
attempts to meet the leaving chilled
water setpoint. Chiller 1 will finish
cooling the leaving water from Chiller 2
down to the system design setpoint.
Staggering the chiller set points is
another control technique that works
well for preferentially loading Chiller 1. If
the cooling load is less than 50 percent
of the system capacity, Chiller 1 would
be able to satisfy the entire call for
cooling. As system loads increase,
Chiller 2 is started to meet any portion of
the load that Chiller 1 can not meet.
Typical Water Piping
All building water piping must be
flushed prior to making the final
connections to the chiller. To reduce heat
loss and prevent condensation,
insulation should be installed. Expansion
tanks are also usually required so that
chilled water volume changes can be
accommodated.
RLC-PRC006-EN14
Application
Considerations
Short Water Loops
The proper location of the temperature
control sensor is in the supply (outlet)
water connection or pipe. This location
allows the building to act as a buffer and
assures a slowly changing return water
temperature. If there is not a sufficient
volume of water in the system to provide
an adequate buffer, temperature control
can be lost, resulting in erratic system
operation and excessive compressor
cycling. A short water loop has the same
effect as attempting to control from the
building return water. Typically, a twominute water loop is sufficient to prevent
problems. Therefore, as a guideline,
ensure the volume of water in the
evaporator loop equals or exceeds two
times the evaporator flow rate. For a
rapidly changing load profile, the
amount of volume should be increased.
To prevent the effect of a short water
loop, the following items should be
given careful consideration: A storage
tank or larger header pipe to increase the
volume of water in the system and,
therefore, reduce the rate of change of
the return water temperature.
Applications Types
• Comfort cooling.
• Industrial process cooling.
• Ice/thermal storage.
• Low temperature process cooling.
Figure A4. Unit isolation recommendations
Typical Unit Installation
Outdoor HVAC equipment must be
located to minimize noise and vibration
transmission to the occupied spaces of
the building structure it serves. If the
equipment must be located in close
proximity to a building, it could be
placed next to an unoccupied space such
as a storage room, mechanical room,
etc. It is not recommended to locate the
equipment near occupied, sound
sensitive areas of the building or near
windows. Locating the equipment away
from structures will also prevent sound
reflection, which can increase levels at
property lines, or other sensitive points.
When physically isolating the unit from
structures, it is a good idea to not use
rigid supports, and to eliminate any
metal-to-metal or hard material contact,
when possible. This includes replacing
spring or metal weave isolation with
elastomeric isolators. Figure A4
illustrates isolation recommendations for
the RTAC.
For chiller sound ratings, installation tips
and considerations on chiller location,
pipe isolation, etc., refer to the
Trane AirCooled Series R Chillers Sound Data and
Application Guide for Noise- Sensitive
Installations.
Elastomeric
Vibration
Eliminators
Flex Conduit
Control Power
Concrete Base
Avoid using the
chiller to support
chiller water
piping.
Neoprene
Isolators
Flex Conduit
Power Wiring
15RLC-PRC006-EN
Application
Considerations
System Options — Ice Storage
Trane air-cooled Series R Chillers are
well suited for ice production. An aircooled machine typically switches to ice
production at night. Two things happen
under this assumption. First, the leaving
brine temperature from the evaporator is
lowered to around 22 to 24°F
[-5.5 to –4.4°C]. Second, the ambient
temperature has typically dropped about
15 to 20°F [8.3 to 11°C] from the peak
daytime ambient. This effectively places
a lift on the compressors that is similar
to daytime running conditions. The
chiller can operate in lower ambient at
night and successfully produce ice to
supplement the next day’s cooling
demands.
The Model RTAC produces ice by
supplying ice storage tanks with a
constant supply of glycol solution. Aircooled chillers selected for these lower
leaving fluid temperatures are also
selected for efficient production of
chilled fluid at nominal comfort cooling
conditions. The ability of Trane chillers to
serve “double duty” in ice production
and comfort cooling greatly reduces the
capital cost of ice storage systems.
When cooling is required, ice chilled
glycol is pumped from the ice storage
tanks directly to the cooling coils. No
expensive heat exchanger is required.
The glycol loop is a sealed system,
eliminating expensive annual chemical
treatment costs. The air-cooled chiller is
also available for comfort cooling duty at
nominal cooling conditions and
efficiencies. The modular concept of
glycol ice storage systems and the
proven simplicity of Trane Tracer
controllers allow the successful blend of
reliability and energy saving
performance in any ice storage
application.
The ice storage system is operated in six
different modes: each optimized for the
utility cost of the hour.
1. Provide comfort cooling with chiller
2. Provide comfort cooling with ice
3. Provide comfort cooling with ice and
chiller
4. Freeze ice storage
5. Freeze ice storage when comfort
cooling is required
6. Off
Tracer optimization software controls
operation of the required equipment and
accessories to easily transition from one
mode of operation to another. For
example:
Even with ice storage systems there are
numerous hours when ice is neither
produced or consumed, but saved. In
this mode the chiller is the sole source of
cooling. For example, to cool the
building after all ice is produced but
before high electrical demand charges
take effect, Tracer sets the air-cooled
chiller leaving fluid setpoint to its most
efficient setting and starts the chiller,
chiller pump, and load pump.
When electrical demand is high, the ice
pump is started and the chiller is either
demand limited or shut down
completely. Tracer controls have the
intelligence to optimally balance the
contribution of ice and chiller in meeting
the cooling load.
The capacity of the chiller plant is
extended by operating the chiller and ice
in tandem. Tracer rations the ice,
augmenting chiller capacity while
reducing cooling costs. When ice is
produced, Tracer will lower the aircooled chiller leaving fluid setpoint and
start the chiller, ice and chiller pumps,
and other accessories. Any incidental
loads that persist while producing ice
can be addressed by starting the load
pump and drawing spent cooling fluid
from the ice storage tanks.
For specific information on ice storage
applications, contact your local Trane
sales office.
Figure A5. Ice storage demand cost savings
RLC-PRC006-EN16
Model
Number
Description
RTAC350AUCONNA FNN 1N X 1 T E NN N0NN10NN
1,2 3 4 5,6,7 8 9 10,11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33
140-500 Tons
Digits 1, 2 — Unit model
RT Rotary chiller
Digit 3 — Unit type
A Air cooled
Digit 4 — Development sequence
C First sequence
Digit 5, 6 & 7 — Nominal capacity
140 140 Nominal tons
155 155 Nominal tons
170 170 Nominal tons
185 185 Nominal tons
200 200 Nominal tons
225 225 Nominal tons
250 250 Nominal tons
275 275 Nominal tons
300 300 Nominal tons
350 350 Nominal tons
375 375 Nominal tons
400 400 Nominal tons
450 450 Nominal tons
500 500 Nominal tons
Digit 8 — Unit voltage
A 200/60/3
C 230/60/3
J 380/60/3
D 400/50/3
4 460/60/3
5 575/60/3
Digit 9 – Manufacturing location
U Water Chiller Business Unit,
Pueblo, CO USA
Digit 10, 11 — Design sequence
CO Factory Input
Digit 12 — Unit basic configuration
N Standard efficiency/performance
configuration
H High efficiency/performance
configuration
Digit 13 — Agency listing
N No agency listing
U UL/CUL listing
Digit 14 — Pressure vessel code
A ASME pressure vessel code
Digit 15 — Evaporator application
F Standard (40-60 F) leaving temp
G Low (Less than 40 F) leaving temp
R Remote (40-60 F) leaving temp
Digit 16 — Evaporator configuration
N Standard pass arrangement, insulated
Digit 17 — Condenser application
N Standard ambient range (25-115 F)
H High ambient capability (25-125 F)
L Low ambient capability (0-115 F)
W Wide ambient capability (0-125 F)
Digit 18 — Condenser fin material
1 Standard aluminum slit fins
2 Copper fins
4 CompleteCoat epoxy coated fins
Digit 19 — Condenser fan/motor
configuration
N STD fans with ODP motors
T STD fans with TEAO motors
W Low noise fans
Digit 20 — Compressor motor starter
type
X Across-the-line starter
Y Wye-delta closed transition starter
Digit 21 — Incoming power line
connection
1 Single point power connection
2 Dual point power connection
Digit 22 — Power line connection type
T Terminal block connection for
incoming line(s)
D Non-fused disconnect switch(es)
for incoming line(s)
C HACR rated circuit breaker(s) for
incoming line(s)
Digit 23 — Unit operator interface
E EasyView operator interface
D DynaView operator interface
Digit 24 — Remote operator interface
N No remote interface
C Tracer Comm 3 interface
L LonTalk compatible (LCI-C) interface
Digit 25 — Control input accessories/
options
N No remote inputs
R Ext. evaporator leaving water
setpoint
C Ext. current limit setpoint
B Ext. leaving water and current limit
setpoint
Digit 26 — Control output accessories/
options
N No output options
A Alarm relay outputs
C Icemaking I/O
D Alarm relay outputs and icemaking
I/O
Digit 27 — Electrical protection options
0 No short circuit rating
5 10,000 Amp short circuit rating
4 35,000 Amp short circuit rating
6 65,000 Amp short circuit rating
Digit 28 — Electrical accessories
N No electrical accessories
F Vapor proof flow switch – 150 psi
E Nema-1 flow switch –150 psi
Digit 29 — Control panel accessories
N No convenience outlet
A 15A 115V convenience outlet (60Hz)
Digit 30 — Service valves
1 With suction service valves
Digit 31 —- Compressor sound
attenuation option
0 No compressor sound attenuation
1 Factory installed compressor sound
attenuation
2 Field installed compressor sound
attenuation
Digit 32 — Appearance options
N No appearance options
A Architectural louvered panels
C Half louvers
G Access guards
B Access guards and half louvers
Digit 33 — Installation accessories
N No installation accessories
R Neoprene in shear unit isolators
F Flange kit for water connections
G Neoprene isolators and flange kit
17RLC-PRC006-EN
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