Trane Rtaaiom3 Manual

101RTAA-IOM-3
Menu 2 - Service #2 Display
20 - Compressor Mode: The current
compressor operating status, as shown
in Figure 53, will be displayed when
this menu item is selected.
21 - Compressor Suction Rfgt.
Temperature: Temperature as read by
the suction temperature sensor (see
Figure 40).
22 - Saturated Evaporator Rfgt
Temperature: Temperature as read by
the saturated evaporator temperature
sensor (see Figure 40).
23 - Evaporator Refrigerant Pressure:
The pressure displayed is the
evaporator...

102RTAA-IOM-3
Menu 4 – Factory Display #1
40 - Leaving Water Temp. Cutout
Setpoint: Establishes a leaving chilled
water temperature, below which the
UCM will begin unloading
compressors and, if necessary,
terminate unit operation. See
discussion in “Leaving Water
Temperature Cutout”. See Table 15 for
proper settings.41 - Low Refrigerant Temp. Cutout
Setpoint: Establishes a saturated
evaporator refrigerant temperature,
below which the UCM will begin
unloading compressors and, if
necessary, terminate unit...

103RTAA-IOM-3
42 - Condenser Limit Setpoint:
Establishes a percentage of the
condenser high pressure cutout, above
which the UCM will begin unloading
compressors and, if necessary,
terminate unit operation.
43 - Lead Lag: Enables or disables the
Auto Lead/Lag feature. See discussion
in “Auto Lead/Lag”.
44 - SI Display Units: When set to
“Enable”, the display units are
converted from OF to IC and PSIG to
Kilopascals Gauge.
45 -Unit Line Voltage (Optional):
Establishes the line voltage coming
into the unit...

104RTAA-IOM-3
Menu 5 – Factory Display #2
50 - Number of Compressors: Set to
the number of compressor installed in
the unit.
51 - Compressor Tons: Set to the rating
in tons, of the each installed
compressor. See Table 2.
52 - Low Water Temperature EXV Gain
Compensation: Set to “E” if the unit
will ever operate with a leaving chilled
water temperature of 40 F or less.
53 - Fan Control: Set to “E”.
54 - Fans Per Circuit: Establishes the
number of fans installed on each
circuit. See Figures 45 and 46.
55 -...

105RTAA-IOM-3
Table 17
Compressor(s) Current Limit Setpoint vs Chiller Current Limit
Setpoint (CLS)
Number of Compressors on a UnitTwo (130-215) Three (240-300) Four (340-400)Number of Number of Number of
compressors compressors compressors
System in operation in operation in operation
CLS One Two One Two Three One Two Three Four120% 120 120 120 120 120 120 120 120 120
100% 120 100 120 120 100 120 120 120 100
80% 120 80 120 120 80 120 120 107 80
60% 120 60 120 90 60 120 120 80 60
40% 80 40 120 60 40 120...

106RTAA-IOM-3
Chilled Water Reset (CWR)
As an option, the UCM will reset the
chilled water temperature setpoint,
based on either the return water
temperature, zone air temperature, or
outdoor air temperature. The following
are selectable:
1. One of four RESET TYPEs, from top
to bottom in order of reset:
 no CWR
RETURN WATER
TEMPERATURE RESET ZONE
TEMPERATURE RESET
OUTDOOR AIR TEMPERATURE
RESET
 The UCM will not permit more than
one type of reset to be selected in
Menu 3.
2. RESET RATIO Setpoints. For...

107RTAA-IOM-3
Leaving Water Temperature Cutout
This temperature cutout provides
protection against freezing caused by
low leaving water temperature. The
setpoint is both factory set and
adjustable from Menu 4. Temperatures
below the setpoint will cause the UCM
to accelerate reduction of chiller
capacity, even to the point of
compressor shutdown. A non-latching
diagnostic will be generated if the LWT
is below the cutout for more than 30
degree F seconds.
There must be a minimum of 5 F
between the cutout...

108RTAA-IOM-3
Auto Lead/Lag
This feature is enabled/disabled in code
43, menu 4. When enabled, the UCM
will start the compressor with the
fewest starts and stop the compressor
with the greatest hours, as determined
by the “Compressor Starts”
accumulator (code 29, menu 2) and the
“Compressor Hours” (code 2A, menu
2). (Display is optional). This will tend to
balance out hours and starts equally
over all compressors. For efficiency
improvement, when there are 2
compressors operating, they will be on...

109RTAA-IOM-3
2. The display will flash the Current
Operating Code “A”, followed by a
fully blank display for all other
diagnostics (CMR, CAR, and IFW
diagnostics). This is to call attention
to the detection of some type of
failure.
Depressing the Display Down key will
advance the display to the “Last (most
recent) Diagnostic Code”. The display
will “flash” if any diagnostic exists that
requires a manual reset to restore full
unit operation. The display will be
continuous if no manual reset is
required...

110RTAA-IOM-3
Table 18
Diagnostics and Troubleshooting Chart
In the table below, a “LATCHING” diagnostic is a condition which shall cause the machine or a portion of the machine as
noted to shut down and shall require a manual reset to restore operation. A diagnostic that is non-latching shall reset
automatically when the condition causing the diagnostic goes away. A non-latching diagnostic shall shut down the machine
or a part of the machine if so indicated. If a diagnostic is informative only, no...