18 BCXC-SVX01A-EN
Mechanical
RequirementsInstallation
Refrigerant Coil Piping
The DX cooling coil in a BCHC/BCVC unit
is equipped with a single distributor
(single-circuited). Some condensing units
have two, independent refrigeration
circuits. Do not manifold two,
independent refrigeration circuits into a
single-circuited DX (evaporator) coil.
Note: Refer to the “Special Note on
Emissions” section on page 2 for
information on handling refrigerants.
Units that are UL listed shall not have
refrigerant temperatures and pressures
exceeding that listed on the unit name-
plate.
Follow accepted refrigeration piping
practices and safety precautions for
typical refrigerant coil piping and compo-
nents. Specific recommendations are
provided with the compressor unit,
including instructions for pressure-testing,
evacuation, and system charging. Leak
test the entire refrigerant system after all
piping is complete. Charge the unit
according to approximate weight
requirements, operating pressures and
superheat/subcooling measurements.
Adjust the thermal expansion valve
setting, if necessary, for proper super-
heat.
Liquid Line
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.
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, moisture-
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 pro-
vided).
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.
• 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
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.
Suction Line
Line sizing:
Properly sizing the suction line
is critical for ensuring that the oil returns
to the compressor throughout the system
operating envelope. If provided, use the
suction line size(s) recommended by the
manufacturer of the compressor unit. The
selected tube diameter(s) must maintain
adequate refrigerant velocities at all
operating conditions.
Routing:
To prevent residual or con-
densed refrigerant from “free-flowing”
toward the compressor, install the suction
line so it slopes slightly — 1 inch per 10
feet of run [1 cm per 3 m] — toward the
evaporator. Avoid putting refrigerant
lines underground. Refrigerant condensa-
tion, installation debris inside the line,
service access, and abrasion/corrosion
can quickly impair system reliability.
Insulation:
After operating the system
and testing all fittings and joints to verify
the system is leak-free, insulate the
suction
lines to prevent heat gain and unwanted
condensation.
Components:
Installing the suction line
requires field installation of these
components: an access port and possibly
a suction filter. Position them as close to
the compressor as possible.
• Access port: The access port is used to
determine suction pressure and adjust
the TEV. It should be located near the
external equalizer line connection. This
port is usually a Schraeder valve with a
core.
• Suction filter: If required by the com-
pressor unit, a replaceable-core suction
filter is installed as close to the compres-
sor unit as possible. Adding manual, ball-
type shutoff valves upstream and
downstream of the filter simplifies
replacement of the filter core.