Trane IntelliPak 1, Installation, Operation And Maintenance Manual, Page: 119 / 164

RT-SVX072A-EN 119
Measuring Superheat
1. Measure the suction pressure at the suction line
gauge access port located near the compressor.
2. Using a Refrigerant/Temperature chart, convert the
pressure reading to a corresponding saturated
vapor temperature.
3. Measure the suction line temperature as close to
the expansion valve bulb, as possible. Use a
thermocouple type probe for an accurate reading.
4. Subtract the saturated vapor temperature obtained
in step 2 from the actual suction line temperature
obtained in step 3. The difference between the two
temperatures is known as “superheat”.
When adjusting superheat, recheck the system
subcooling before shutting the system “Off”.
N No otte e:: If unit includes the modulating reheat
dehumidification option, adjust superheat only
in the cooling mode of operation.
N No otte e:: Due to the placement of the sensors that control
the refrigeration system's electronic expansion
valves, it is possible that there will be differences
between what is measured by the method
described above, and what is shown on the
Symbio controller display for its current
superheat measurement. This by itself is not a
cause for concern or reason to adjust operating
parameters in the Symbio controller.
When communicating with Trane Product
Support, please report the superheat value(s)
described above (obtained with refrigerant
gauges), and follow their guidance for any
controller adjustments which should be
attempted.
Charging by Subcooling
Before beginning the charging procedure, locate the
“Pressure Curves,” p. 102 figure which corresponds to
your refrigeration system. This plot will indicate the
approximate discharge pressure which should be
observed when the unit has the correct amount of
subcooling.
The outdoor ambient temperature must be between 65
and 105°F and the relative humidity of the air entering
the evaporator must be above 40 percent. When the
temperatures are outside of these ranges, measuring
the operating pressures can be meaningless. Do not
attempt to charge the system with hot gas bypass
operating (if applicable). Disable the low ambient
dampers in the “Open” position (refer to the “Low
Ambient Options” section) and de-energize the hot gas
bypass valves before taking performance
measurements. With the unit operating at “Full Circuit
Capacity”, acceptable subcooling ranges for air-cooled
units is between 10°F to 23°F.
N No otte e:: If unit includes the modulating reheat
dehumidification control option, adjust
subcooling only in the cooling mode of
operation.
Measuring Subcooling
1. At the liquid line service port, measure the liquid
line pressure. Using an R–410A pressure/
temperature chart, convert the pressure reading
into the corresponding saturated temperature.
2. Measure the actual liquid line temperature as close
to the liquid line service port as possible. To ensure
an accurate reading, clean the line thoroughly
where the temperature sensor will be attached.
After securing the sensor to the line, insulate the
sensor and line to isolate it from the ambient air.
Use a thermocouple type probe for an accurate
reading.
N No otte e:: Glass thermometers do not have sufficient
contact area to give an accurate reading.
3. Determine the system subcooling by subtracting
the actual liquid line temperature (measured in step
2) from the saturated liquid temperature (converted
in step 1).
Low Ambient Options
Operation
When the Low Ambient option is selected for IntelliPak
1 with Symbio systems, its function will be
accomplished by the usage of at least one variable
speed condenser fan motor on each circuit to actively
keep the refrigerant discharge pressure within a
defined range, in order to maintain acceptable
refrigerant pressure differences throughout the system.
The low ambient modulating output(s) on the
compressor module controls the condenser fan airflow
for each refrigerant circuit in response to saturated
condensing temperature.
When the head pressure control has staged up to fan
stage 2 or 3, the modulating output will be at 100%.
When the head pressure control is at fan stage 1, the
modulating output will control the saturated
condensing temperature to within the programmable
“condensing temperature low ambient control point”.
The following Table gives the minimum starting
temperatures for both “Standard” & “Low” Ambient
units. Do not start the unit in the cooling mode if the
ambient temperature is below the recommended
operating temperatures.
U Un niitt S Stta arrttu up p