Trane CAH-SVX01A-EN manual Valve Damage, Installation, Suction Lines

Installation

•Thermal expansion valve. The expansion valve is the throttling device that meters the refrigerant into the evaporator coil. Metering too much refrigerant floods the compressor; metering too little elevates the compressor temperature. Choosing the correct size and type of expansion valve is critical to assure it will correctly meter refrigerant into the evaporator coil throughout the entire operating envelope of the system. Correct refrigerant distribution into the coil requires an expansion valve for each distributor.

The thermal expansion valve must be selected for proper size and capacity. The size of the expansion valve should cover the full range of loadings. Check that the valve will successfully 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 34 and install the expansion valve directly to the liquid connections.

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 result in damage to internal components.

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 1/4-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.

Figure 34. Type F refrigerant coil with packed elbow

	Perforated plate	Cut here for
Panel	(packed elbow)
		piping

Venturi type distributor

Coil

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 33.

•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.

34 CAH-SVX01A-EN