Trane Rtaaiom3 Manual

							121RTAA-IOM-3
Pre-Start
Checkout
General
When installation is complete, but prior
to putting the unit into service, the
following pre-start procedures must be
reviewed and verified correct:
[  ] Inspect all wiring connections to be
sure they are clean and tight.
WARNING: Disconnect all electric
power including remote
disconnects before servicing’
Failure to disconnect power
before servicing can cause severe
personal injury or death.
Caution: Check the tightness of all
connections in the compressor
power circuits (disconnects,
terminal block, contactors,
compressor junction box terminals,
etc.). Loose connections can cause
overheating at the connections and
undervoltage conditions at the
compressor motor.
[  ] Verify that all refrigerant valves, as
shown in Figure 37, are “OPEN”.
Caution: Do not operate the unit
with the compressor, oil discharge
and liquid line service valves
“CLOSED”. Failure to have these
“OPEN” may cause serious
compressor damage.
[  ] Check the power supply voltage to
the unit at the main power fused
disconnect switch. Voltage must be
within the voltage utilization range,
given in Table 10 and also stamped
on the unit nameplate. Voltage
imbalance must not exceed 2
percent. Refer to “Unit Voltage
Imbalance”, below.
WARNING: Disconnect all electric
power including remote
disconnects before servicing.
Failure to disconnect power
before servicing can cause severe
personal injury or death.
[  ] Check the unit power phasing to be
sure that it has been installed in an
“ABC” sequence. Refer to “Unit
Voltage Phasing”, below.
WARNING: It is imperative that
L1 -L2-L3 in the starter be
connected in the A-B-C phase
sequence to prevent equipment
damage due to reverse rotation.
[  ] Check the condenser fans to be sure
that they rotate freely in the fan
openings and that each is securely
attached to its fan motor shaft.
WARNING: Disconnect all electric
power Including remote
disconnects before servicing.
Failure to disconnect power
before servicing can cause severe
personal injury or death.
[  ] Energize the compressor sump
heaters by closing the unit main
disconnects. If unit-mounted
disconnects are used, they must
also be closed. If the unit does not
have the optional control power
transformer, 115 VAC power must
be field supplied to terminals 1TB3-1
AND 1TB3-2. The Chiller Switch
must be in the STOP/RESET
position.
Caution: The compressor sump
heaters must be energized for a
minimum of 24 hours prior to unit
operation, to prevent compressor
damage caused by liquid
refrigerant in the compressor at
start-up. 
						

							122RTAA-IOM-3
[  ] Energize the evaporator and
Domestic Water Heater heat tape.
[  ] Fill the evaporator chilled water
circuit. Refer to Table 1 for
evaporator liquid capacities. Vent
the system while it is being filled.
Open the vent on the top of the
evaporator during filling and close
when filling is completed.
Customer Note
The use of improperly treated or
untreated water in this equipment may
result in scaling, erosion, corrosion,
algae or slime. The services of a
qualified water treatment specialist
should be engaged to determine what
treatment, if any, is advisable. The
Trane Company warranty specifically
excludes liability for corrosion, erosion
or deterioration of Trane equipment.
Trane assumes no responsibilities for
the results of the use of untreated or
improperly treated water, or saline or
brackish water.
Caution: Do not used untreated or
improperly treated water.
Equipment damage may occur.
Caution: Do not fill the water
systems unless the evaporator and
Domestic Water Heater heat tapes
have been energized.
[  ] Close the fused-disconnect
switch(es) that supplies power to
the chilled water pump starter.
[  ] Start the chilled water pump to
begin circulation of the chilled water.
Inspect all piping for leakage and
make any necessary repairs.
[  ] With chilled water circulating
through the system, adjust water
flow and check water pressure drop
through the evaporator. Refer to
Figure 23.
[  ] Adjust the chilled water flow switch
(if installed) for proper operation.
[  ] Prove Chilled Water Pump Interlock
and External Auto/Stop as described
in Interconnecting Wiring: Chilled
Water Pump Interlock and External
Auto/Stop.
Caution: Chilled Water Pump
Interlock and External Auto/Stop
information must be adhered to or
equipment damage may occur.
[  ] Check and set, as required, all UCM
Menu items.
[  ] Stop the chilled water pump.
Unit Voltage
Power Supply
Voltage to the unit must meet the
criteria given in Table 10. Measure each
leg of the supply voltage at the unit
main power fused-disconnect. If the
measured voltage on any leg is not
within specified range, notify the
supplier of the power and correct the
situation before operating the unit.
Caution: Inadequate voltage to the
unit can cause control components
to malfunction and shorten the life
of relay contact, compressor
motors and contactors.
Unit Voltage Imbalance
Excessive voltage imbalance between
the phases of a three-phase system can
cause Motors to overheat and
eventually fail. The maximum
allowable imbalance is 2 percent.
Voltage imbalance is determined using
the following calculations:
% Imbalance = (V
x - V
ave) x 100
V
ave
V
ave = (V
1 + V
2 + V
3) 
/ 3
V
x = phase with greatest difference
from V
ave (without regard to sign)
For example, if the three measured
voltages are 221, 230, and 227 volts, the
average would be:
221 +230 +227 
= 226
3
The percentage of imbalance is then:
100 (221 - 226) 
= 2.2%
226
This exceeds the maximum allowable
(2%) by 0.2 percent. 
						

							123RTAA-IOM-3
Unit Voltage Phasing
It is important that proper rotation of
the compressors be established before
the unit is started. Proper motor
rotation requires confirmation of the
electrical phase sequence of the power
supply. The motor is internally
connected for clockwise rotation with
the incoming power supply phased
A, B, C.
Basically, voltages generated in each
phase of a polyphase alternator or
circuit are called phase voltages. In a
three-phase circuit, three sine wave
voltages are generated, differing in
phase by 120 electrical degrees. The
order in which the three voltages of a
three-phase system succeed one
another is called phase sequence or
phase rotation. This is determined by
the direction of rotation of the
alternator. When rotation is clockwise
phase sequence is usually called
“‘ABC”, when counterclockwise,
“CBA”.This direction may be reversed outside
the alternator by interchanging any two
of the line wires. It is this possible
interchange of wiring that makes a
phase sequence indicator necessary if
the operator is to quickly determine the
phase rotation of the motor.
Proper compressor motor electrical
phasing can be quickly determined and
corrected before starting the unit. Use a
quality instrument, such as the
Associated Research Model 45 Phase
Sequence Indicator shown in Figure 55,
and follow this procedure.
 WARNING
IT IS IMPERATIVE THAT L1-L2-L3
IN THE STARTER BE
CONNECTED IN THE A-B-C
PHASE SEQUENCE TO PREVENT
EQUIPMENT DAMAGE DUE TO
REVERSE ROTATION.
Figure 55
Associated Research Model 45
Phase Sequence Indicator 
						

							124RTAA-IOM-3
1. Turn the Chiller Switch on the UCM
to the STOP/RESET position.
2. Open the electrical disconnect or
circuit protection switch that
provides line power to the line power
terminal block(s) in the starter panel
(or to the unit-mounted disconnect).
3. Connect the phase sequence
indicator leads to the line power
terminal block, as follows:
Phase Seq. LeadTerminal
Black (Phase A).................. L1
Red (Phase B).................... L2
Yellow (Phase C)................ L3
4. Turn power on by closing the unit
supply power fused- disconnect
switch.
5. Read the phase sequence on the
indicator. The “ABC” LED on the face
of the phase indicator will glow if
phase is “ABC”.
WARNING: To prevent injury or
death due to electrocution, take
extreme care when performing
service procedures with electrical
power energized.
6. If the “CBA” indicator glows instead,
open the unit main power disconnect
and switch two line leads on the line
power terminal block(s) (or the unit
mounted disconnect). Reclose the
main power disconnect and recheck
the phasing.
Caution: Do not interchange any
load leads that are from the unit
contactors or the motor terminals.
7. Reopen the unit disconnect and
disconnect the phase indicator.
Water System
Flow Rates
Establish a balanced chilled water flow
through the evaporator. The flow rates
should fall between the minimum and
maximum values given in Table 1.
Chilled water flow rates below the
minimum values will result in laminar
flow, which reduces heat transfer and
causes either loss of EXV control or
repeated nuisance, low temperature
cutouts. Flow rates that are too high
can cause tube erosion and damage to
the tube supports and baffles in the
evaporator.
Caution: Once the evaporator and
Domestic Water Heater (optional)
are filled with water, the heat tapes
must be energized to protect the
evaporator from freezing and
bursting if the outdoor air
temperature drops below freezing.
Water System
Pressure Drop
Measure chilled water pressure drop
through the evaporator at the field-
installed pressure taps on the system
water piping. See Figure 22. Use the
same gauge for each measurement. Do
not include valves, strainers fittings in
the pressure drop readings.
Measure the water pressure drop
through the Domestic Water Heater at
the field installed vent and drain
connections. See Figure 24. Use the
same gauge for each measurement. Do
not include valves, strainers, fittings in
pressure drop readings.
Pressure drop readings should be
approximately those shown in the
Pressure Drop Charts, Figure 23 for the
evaporator and Figure 25 for the
Domestic Water Heater (optional).
UCM Set-up
Refer to “Menu Function Descriptions
and Selection” for instruction on the
set-up of the UCM. 
						

							125RTAA-IOM-3
Start-Up
Procedures
General
If the pre-start checkout, as discussed
above, has been completed, the unit is
ready to start. UCM controls are shown
in Figure 51 and UCM Sequence of
Operation is shown in Figures 56
and 57. Complete each step, in
sequence, as follows:
[  ] Move the Chiller Switch on the UCM
to the STOP/RESET position.
[  ] As necessary, adjust the setpoint
values in the UCM menus, as
described in “Menu Function
Descriptions and Selections”.
[  ] Close the fused-disconnect switch
for the chilled water pump. Energize
the pump to start chilled water
circulation.
[  ] Check the service valves on the
discharge line, suction line, oil line
and liquid line for each circuit. These
valves must be open (backseated)
before starting the compressors.
Caution: To prevent compressor
damage, do not operate the unit
until all refrigerant and oil line
service valves are opened.
[  ] Energize the compressor sump
heaters, if not already energized.
Also close the unit-mounted
disconnect, if used.
Caution: The compressor sump
heaters must be energized for a
minimum of 24 hours prior to unit
operation, to prevent compressor
damage caused by liquid
refrigerant in the compressor at
start-up.
[  ] Verify that the evaporator heat tape
is energized.
[  ] Verify that the chilled water pump
runs for one minute after the chiller
is commanded to stop (for normal
chilled water systems). See page
[  ] Move the Chiller Switch to AUTO
LOCAL. If the chiller control 1 U 1
calls for cooling and all safety
interlocks are closed, the unit will
start. The compressor(s) will load
and unload in response to the
temperature of the leaving chilled
water temperature.If optional low-ambient is installed,
outside air temperature must be
above the minimum starting
ambients, as shown in Table 1, for
continued unit operation. Use Table
1 to determine proper setpoints for
the optional low ambient lockout
setpoint, if used. Also refer to the
wiring diagrams in Figures 34
thru 36.
Once the system has been operating
for approximately 30 minutes and has
become stabilized, complete the start-
up procedures, as follows:
[  ] Check the evaporator refrigerant
pressure (23) and the condenser
refrigerant pressure (25) in Menu 2
on the UCM. The pressures are
referenced to sea level (14.6960
psia)
[  ] Check the liquid line sight glasses.
The refrigerant flow past the sight
glasses should be clear. Bubbles in
the refrigerant indicate either low
refrigerant charge or excessive
pressure drop in the liquid line. A
restriction in the line can sometimes
be identified by a noticeable
temperature differential between
the two sides of the restriction. Frost
may often form on the line at this
point. Proper refrigerant charges are
shown in Table 1.
Caution: A clear sight glass alone
does not mean that the system is
properly charged. Also check
system superheat, subcooling, and
unit operating pressures.
[  ] Measure the system superheat.
Refer to “System Superheat, below.
[  ] Measure the system subcooling.
Refer to “System Subcooling”,
below.
[  ] A shortage of refrigerant is indicated
if operating pressures are low and
subcooling is also low. If the
operating pressures, sight glass,
superheat and subcooling readings
indicate a refrigerant shortage, gas-
charge refrigerant into each circuit,
as required. With the unit running,
add refrigerant vapor by connecting
the charging line to the suction
service valve and charging through
the backseat port until operating
conditions become normal.
Caution: If both suction and
discharge pressures are low but
subcooling is normal, a problem
other than refrigerant shortage
exists. Do not add refrigerant, as
this may result in overcharging the
circuit.
Caution: Use only refrigerants
specified on the unit nameplate, to
prevent compressor damage and
insure full system capacity.
[  ] If operating conditions indicate a
refrigerant overcharge, remove
refrigerant at the liquid line service
valve. Allow refrigerant to escape
slowly, to minimize oil loss. Do not
discharge refrigerant into the
atmosphere.
WARNING: Do not allow
refrigerant to directly contact
skin or injury from frostbite may
result.
System Superheat
Normal superheat for each circuit is
approximately 8 F at full operating
load. Superheat temperature can be
expected to be moving around the 8 F
setpoint when the chiller is pulling
down, the compressor slide valve is
being modulated, or the fans are
staging on either the same or opposite
circuits. Superheat can be expected to
settle out at approximately 8 F when
the above items stabilize.
System Subcooling
Normal subcooling for each circuit
ranges from 11 F to 20 F, depending on
the unit. If subcooling for either circuit
does not approximate these figures,
check the superheat for the circuit and
adjust, if required. If superheat is
normal but subcooling is not, contact a
qualified service technician. 
						

							126
RTAA-IOM-3
Figure 56 
Unit Sequence of Operation – RTAA 240 to 400 Tons
(Continued on Next Page) 
						

							127RTAA-IOM-3
(Continued from Previous Page)
2307-1566C 
						

							128
RTAA-IOM-3
Figure 57 
Unit Sequence of Operation – RTAA 130 to 200 Tons
2306-9122A 
						

							129RTAA-IOM-3
Unit Shutdown
Procedures
Temporary Shutdown
and Restart
To shut the unit down for a short time,
use the following procedure:
1. Move the Chiller Switch to STOP/
RESET. The compressors will
continue to operate and, after
unloading for 20 seconds, will stop
when the compressor contactors de-
energize. The condenser fans will be
de-energized at this time.
2. The unit disconnect switch and unit
mounted disconnect (if installed)
should remain closed to keep the
compressor sump heaters energized.
3. Maintain power to keep the
evaporator and Domestic Water
Heater heat tape(s) energized.
4. Stop the chilled water circulation by
turning off the chilled water pump.
To restart the unit after a temporary
shutdown, restart the chilled water
pump and move the Chiller Switch to
either of the AUTO positions. The unit
will start normally, provided the
following conditions exist:
1. The UCM must receive a call for
cooling and the differential- to-start
must be above the setpoint.
2. All system operating interlocks and
safety circuits must be satisfied.
Extended Shutdown
Procedure
The following procedure is to be
followed if the system is to be taken out
of service for an extended period of
time, e.g. seasonal shutdown:
1. Test the condenser and high-side
piping for refrigerant leakage.
2. Open the electrical disconnect
switches for the chilled water pump.
Lock the switch in the “OPEN”
position.
Caution: Lock the chilled water
pump disconnect open to prevent
pump damage.
3. Close all chilled water supply valves.
Drain the chilled water from the
evaporator. If the unit will be
exposed to freezing ambient
conditions, flush the evaporator with
an antifreeze solution and energize
the evaporator heat tape.
Caution: To prevent damage to the
evaporator by freezing, flush the
evaporator with an antifreeze
solution and energize the
evaporator heat tape.
4. Drain the Domestic Water Heater and
any exposed system piping to
prevent the possibility of freeze-up.
Use the pressure tap on the water
outlet to force compressed air
through the water coils of the unit
and assure that no water blocks any
of the tubes. Be certain that the drain
valve on the water inlet is open
before applying compressed air to
the water coils. Energize the
Domestic Water Heater heat tape.
Caution: To prevent damage to the
Domestic Water Heater by
freezing, blow out water from coils
and energize the Domestic Water
Heater heat tape.
5. Open the unit main electrical
disconnect and unit-mounted
disconnect (if installed) and lock on
the “OPEN” position. If optional
control power transformer is not
installed, open and lock the 115 V
disconnect.
Caution: Lock the disconnects on
the “OPEN” position to prevent
accidental start-up and damage to
the system when it has been setup
for extended shutdown.
6. At least every three months
(quarterly), check the pressure in the
unit to verify that the refrigerant
charge is intact. 
						

							130RTAA-IOM-3
System Restart After
Extended Shutdown.
Follow the procedures below to restart
the unit after extended shutdown:
1. Verify that the liquid line service
valves, oil line, compressor
discharge service valves and suction
service valves (if installed) are open
(backseated).
Caution: To prevent damage to the
compressor, be sure that all
refrigerant valves are open before
starting the unit.
2. Close the main disconnect and unit
mounted disconnect (if installed) to
energize the compressor sump
heaters. If the optional control
transformer is not installed, it will be
necessary to close the disconnect for
115 VAC power to 1TB3-1 and
1TB3-2.
Caution: The compressor sump
heaters must be energized for a
minimum of 24 hours prior to unit
operation, to prevent compressor
damage caused by liquid
refrigerant in the compressor at
start-up.
3. Maintain power to the evaporator
heat tape connections.
4. Check the oil separator oil level. See
“Oil Separator Level Check”.
5. Fill the evaporator chilled water
circuit. Refer to Table I for evaporator
liquid capacities. Vent the system
while it is being filled. Open the vent
on the top of the evaporator during
filling and close when filling is
completed.
Caution: Do not use untreated or
improperly treated water.
Equipment damage may occur.
6. Close the fused-disconnect switch
that provides power to the chilled
water pump.
7. Start the chilled water pump and,
while chilled water is circulating,
inspect all piping for leakage. Make
any necessary repairs before starting
the unit.
8. While the chilled water is circulating,
adjust the chilled water flow and
check the chilled water pressure drop
through the evaporator. Refer to
“Water System Flow Rates” and
“Water System Pressure Drop”.
9. Adjust the flow switch on the
evaporator piping (if installed) for
proper operation.
10. Stop the chilled water pump. The
unit is now ready for start-up as
described in “Start-Up Procedures”.