Charging By Subcooling; Measuring Subcooling; Low Ambient Options; Operation - Trane IntelliPak 1 with Symbio 800 Installation, Operation And Maintenance Manual

Unit Start-up
temperatures is known as "superheat".
When adjusting superheat, recheck the system subcooling
before shutting the system "Off".
Note: If unit includes the modulating reheat
dehumidification option, adjust superheat only in the
cooling mode of operation.
Note: 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. 99 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.
Note: 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.
Note: Glass thermometers do not have sufficient
contact area to give an accurate reading.
116
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.
Table 56. Minimum starting temperatures for air-
cooled units
Minimum Starting Ambient
Unit Size Standard
20 & 40 50°
25 & 30 50°
50, 55
50°
60 50°
70-130 50°
Note: Min. starting ambients in °F and is based on unit operating at min.
step of unloading and 5 mph wind across condenser.
Standard Ambient Condenser Fans
Standard ambient units stage condenser fans down to a
minimum of one fan per circuit. All standard ambient units
ship with the Symbio™ controller set to allow mechanical
cooling down to 50°F outdoor temperature. This setting is
adjustable. Below table lists the minimum recommended
mechanical cooling setting for standard ambient units by
application and unit type.
Low Ambient
0°
0°
0°
0°
0°
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