Chapter 4 Refrigeration Connections 21
Liebert.CRV Series Air Conditioner User Manual
Table 4-2 Pipe diameters (Indoor unit to condenser)
Model
External diameter x minimum thickness (mm)
Gas Liquid
CR020RA 19 × 1.2 16 × 1
CR035RA 22 × 1.2 19 × 1.2
Note: the diameters in the table is standard pipe dismeters (invalid for equivalent lengths up to 50m)
4.1.3 Installing Pipelines
The following operations must be carried out by an experienced refrigeration technician.
Warning
The discharge operation of the room unit pressurized with nitrogen (at 2bar) and the de-brazing of the bottoms from the
connections must be carried out as last operations, immediately followed by the connection and emptying of the whole system.
1. Lay the piping, taking note of the following:
1) Brazing:
All joints must be braze-brazed.
Avoid butt brazes by using sleeves or enlarging one of the pipes using a pipe opener.
Use silver-based solders and the correct apparatus.
Guarantee a correct braze as a refrigerant leak, or a faulty braze which leads to a leak later on, can seriously
damage the air conditioner.
2) Always use large-radius curves (bending radius at least equal to pipe diameter). Bend the pipes as follows:
Soft copper: by hand or bending device.
Hard copper: use preformed curves. Do not overheat the pipes when brazing so as to minimize oxidation.
2. Connect the pipes to the condenser:
1) Condensers with butt-brazed pipe connections: cut the pipe, enlarge it and braze it to the pipeline.
2) Condensers with threaded tap connections: flange the pipes and connect.
Note: respect the direction of refrigerant flow (see labels on refrigerant connections).
3. Wash out the pipelines as follows:
1) Plug up the free ends of the pipes.
2) Connect a helium or nitrogen cylinder, fitted with a reducer (max. pressure 10bar), to the ¼" SAE Schrader cock of
the condenser.
3) Pressurize the pipes with helium or nitrogen.
4) Unplug the pipes instantaneously.
5) Repeat 1) - 4) several times.
Note: This operation is especially important when hard copper piping is used.
4. Open all the room unit shut-off valves.
5. Discharge the room unit pressurized with nitrogen (at 2bar) opening the charge cocks so that all the branches of
the circuit are discharged (e.g. on the receiver, on the low pressure side and on the compressor delivery).
6. De-braze the bottoms from the connections of the room unit.
7. Fix (braze) the pipes to the connections on the air conditioner.
8. Connect the refrigerant safety valve to the outdoor with a 16mm copper pipe.
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