CLCH-SVX03C-EN
59
Coil Piping and Connections
operate at the lightest load condition. For improved modulation, choose expansion valves with
balanced port construction and external equalization.
Cut the process tube and cap assembly from the liquid connection as shown in
Figure 55
and install
the expansion valve directly to the liquid connections.
Suction Lines
Line sizing.
Proper suction-line sizing is required to guarantee the oil returns to the compressor
throughout the system’s operating envelope. At the same time, the line must be sized so that the
pressure drop does not excessively affect capacity or efficiency. To accomplish both objectives, it
may be necessary to use two different line diameters: one for the horizontal run and for vertical
drops, and another for the vertical lifts.
Routing.
To prevent residual or condensed refrigerant from “free-flowing” toward the
compressor, install the suction line so it slopes slightly—that is, by ¼ inch to 1 inch per 10 feet of
run [1 cm per 3 m]—toward the evaporator. When the application includes a suction riser, oil must
be forced to travel the height of the riser. Riser traps and double risers are unnecessary in the
suction line when the refrigerant coil is used with Trane condensing units.
Avoid putting refrigerant lines underground.
Refrigerant condensation or installation debris
inside the line, service access, and abrasion/corrosion can quickly impair reliability.
Insulation.
Any heat that transfers from the surrounding air to the cooler suction lines increases
the load on the condenser (reducing the system’s air-conditioning capacity) and promotes
condensate formation (adversely affecting indoor air quality). After operating the system and
testing all fittings and joints to verify the system is leak-free, insulate the suction lines all the way
to inner side panel to prevent heat gain and unwanted condensation.
Components.
Installing the suction line requires field installation of these components: a filter,
access port, and a Frostat™ control when the refrigerant coil is used with Trane condensing units.
Position them as close to the compressor as possible.
Note:
Placement of the Frostat control is illustrated in
Figure 54 on page 57
.
•
Filter. The suction filter prevents contaminants, introduced during installation, from entering
the compressor. For this reason, the suction filter should be the replaceable-core type, and a
clean core should be installed after the system is cleaned up.
•
Access port. The access port is used to determine suction pressure. This port is usually a
Schraeder valve with a core.
•
Frostat™ coil frost protection. The Frostat control is the preferred method for protecting
evaporator coils from freezing when the refrigerant coil is used with Trane condensing units.
It senses the suction-line temperature and temporarily disables mechanical cooling if it detects
frost conditions. The control is mechanically attached to the outside of the refrigerant line, near
the evaporator, and wired to the unit control panel.
•
Ball shutoff valve. Adding manual, ball-type shutoff valves upstream and downstream of the
filter simplifies replacement of the filter core.
