Trane LPC Install And Operation Instructions page 33

Refrigerant Coil Piping
Units that are UL listed shall not
have refrigerant temperatures and
pressures exceeding that listed on
the unit nameplate.
For unit-installed refrigerant coils, packed
elbows are provided. Make pipe connec-
tions as shown in Figure I-MR-2.
Note: DX coils ship dehydrated and
charged with a dry air holding charge. To
prevent leaks and system contamination,
do not break the seal until the coil is
installed. All liquid lines have a
process tube attached. Use only a pipe
cutter to cut the process tube.
Ensure the coil is installed correctly with
airflow in the same direction as indicated
on the coil nameplate or casing (field
installed coils). The suction connection
must be at the bottom of the suction
header.
Follow accepted refrigeration piping
practices and safety precautions for
typical refrigerant coil piping and compo-
nents. Specific recommendations are
provided with the highside components,
including instructions for pressure-testing,
evacuation, and system charging. Follow
the general recommendations for
component selection and line sizing
below. Leak test the entire refrigerant
system after all piping is complete.
Charge the unit according to approximate
weight requirements, operating pres-
sures and superheat/subcooling mea-
surements. Adjust the thermal expansion
valve setting if necessary.
General Refrigerant Piping
Recommendations
Note: Refer to the note on page two of
this manual regarding the handling of
refrigerants. Line Sizing: Properly sizing
the liquid line is critical to a successful
application. If provided, use the liquid line
size recommended by the manufacturer
of the compressor unit. The selected tube
diameter must be as small as possible,
while still providing at least 5°F [2.7°C] of
subcooling at the expansion valve
throughout the operating envelope.
LPC-SVX01C-EN
Installation
Routing: Install the liquid line with a slight
slope in the direction of flow so that it can
be routed with the suction line. Minimize
tube bends and reducers because these
items tend to increase pressure drop and
reduce subcooling at the expansion
valve.
Insulation: The liquid line is generally
warmer than the surrounding air, so it
does not require insulation.
Components: Liquid-line refrigerant
components necessary for a successful
job include an expansion valve, mois-
5 / "
8 ture-indicating sight glass, filter drier,
manual ball shutoff valves, access port,
and possibly a solenoid valve. Position
these components as close to the
evaporator as possible.
• Thermal expansion valve (TEV): Select
the TEV based on the actual evaporator
capacity, considering the full range of
loadings. Verify that the valve will
successfully operate at the lightest load
condition, considering if hot gas bypass is
to be used. For improved modulation,
choose a TEV with balanced port con-
struction and an external equalizer
connection. The valve must be designed
to operate against a back pressure of 20
psi higher than actual evaporator
pressure. Install the TEV directly on the
coil liquid connection
(distributor provided).
The remote expansion-valve bulb should
be firmly attached to a straight, well-
drained, horizontal section of the suction
line. The external equalizer line should be
inserted downstream of the remote bulb.
Coil
Figure I-MR-3. Refrigerant Coil with Packed Elbow
mechanical
requirements
• Moisture-indicating sight glass: Install a
moisture-indicating sight glass in the
liquid line between the expansion valve
and filter drier. The sight glass should be
sized to match the size of the liquid line.
• Filter drier: Install a properly sized liquid
line filter-drier upstream from the
expansion valve and as close to the
evaporator coil as possible. Select the
filter-drier for a maximum pressure drop
of 2 psi at the design condition.
Manual, ball-type shutoff valves on either
side of the filter drier allows replacement
of the core without evacuating the entire
refrigerant charge.
• Access port: The access port allows the
unit to be charged with liquid refrigerant
and is used to determine subcooling. This
port is usually a Schraeder valve with a
core.
• Solenoid valve: If required by the
compressor unit, install the solenoid
valve between the filter drier and sight
glass.
CAUTION
Valve Damage!
Disassemble the thermal expansion
valve before completing the brazing
connections. If necessary, wrap the
valve in a cool wet cloth while brazing.
Failure to protect the valve from high
temperatures may damage internal
components.
Perforated Plate
Panel (Packed Elbow)
Distributor
Cut here
for piping
33