Liebert 3000 installation manual 7.3Piping Considerations, Refrigerant Loop

Split System Models

7.3Piping Considerations

7.3.1 Refrigerant Loop

! CAUTION

All local codes for handling refrigerant must be followed.

NOTE

As R22 and R407C are similar in properties, proper safety equipment and proper refrigeration tools are required on both types. Check unit nameplate for correct refrigerant type before topping off or recharging a system.

NOTE

Refrigerant R407C uses a POE (polyol ester) lubricant. The R407C refrigerant must be introduced and charged from the cylinder only as a liquid.

NOTE

When installing field piping, care must be taken to protect all refrigerant lines from the atmosphere, especially when using refrigerants with POE oils. Do not allow the piping to stand open to air for more than 15 minutes. Units designed for R407C have a compressor which contains POE oil that is very hygroscopic; that is, it quickly absorbs water from the air. The longer the compressor piping is left open to air, the harder it will be to fully evacuate. If left open too long, the POE oil may need to be replaced before achieving the required vacuum level.

NOTE

Complete all piping and evacuate lines before connecting quick connects when using an optional sweat adapter kit and field installed hard piping.

Follow all proper brazing practices including a dry nitrogen purge to maintain system cleanliness.

All split systems require two refrigerant lines (an insulated copper suction line and a copper liquid line) between the evaporator and the condensing unit.

Two possible methods exist for installing the copper suction and liquid lines.

1.Using an optional Sweat Adapter Kit and hard piping between the two units.

2.Using optional pre-charged line sets (for 3 ton R22 models only).

All refrigeration piping should be installed with high temperature brazed joints. Prevailing good refrigeration practices should be employed for piping supports, leak testing, evacuation, dehydration, and charging of the refrigeration circuits. The refrigeration piping should be isolated from the build- ing by the use of vibration isolating supports.

It is important to handle the pre-charged lines for 3 ton units with care so they will not get kinked or damaged. Use tube benders and make all bends before making connections to either end. Coil any excess tubing in a horizontal plane with the slope of the tubing toward the condensing unit.

To prevent tube damage when sealing openings in walls and to reduce vibration transmission, use a soft flexible material to pack around the tubes.

When installing remote condensing units mounted above the evaporator, the suction gas line should be trapped at the evaporator. This trap will retain refrigerant oil in the off cycle. When the unit starts, oil in the trap is carried up the vertical riser and returns to the compressor.

Refrigerant charge requirements: Total refrigerant charge will be required only if units are evacuated during installation or maintenance. Total refrigerant charge = evaporator + lines + condensing unit.

NOTE

All condensing units and 3-ton evaporator units are fully charged with refrigerant. All 5 ton evaporator units include a nitrogen holding charge only. See Table 21 for field charge required. If field-supplied refrigerant piping is installed, refrigerant must be added to the system.

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