SYSVRF2 IM

5.5 Piping connections between outdoor units

The piping connecting the outdoor units should be horizontal and

must not be higher than the refrigerant outlets. If necessary, to avoid

obstacles the piping may be vertically offset below the outlets. When

inserting a vertical offset to avoid an obstacle, the whole outdoor

piping should be offset, rather than just the section adjacent to the

obstacle. Refer to Figure 5-9 to 5-12.

Fig.5-7

Fig.5-8

√ Correct

Fig.5-9

√ Correct

× Incorrect

Fig.5-11

Fig.5-10

Fig.5-12

× Incorrect

5.6 Piping flushing

To remove dust, other particles and moisture, which could cause

compressor malfunction if not flushed out before the system is run,

the refrigerant piping should be flushed using nitrogen. Pipe flushing

should be performed once the piping connections have been

completed with the exception of the final connections to the indoor

units. That is, flushing should be performed once the outdoor units

have been connected but before the indoor units are connected.

The liquid and gas sides can be flushed simultaneously; alternatively,

one side can be flushed first and then Steps 1 to 8 repeated, for the

other side. The flushing procedure is as follows:

Cover the inlets and outlets of the indoor units to prevent dirt

getting blown in during pipe flushing. (Pipe flushing should be

carried out before connecting the indoor units to the piping

system.)

Attach a pressure reducing valve to a nitrogen cylinder.

Connect the pressure reducing valve outlet to the inlet on the

liquid (or gas) side of the outdoor unit.

Use blind plugs to block all liquid (gas) side openings, except for

the opening at the indoor unit which is furthest from the outdoor

units (“Indoor unit A” in Figure 5-13).

Start to open the nitrogen cylinder valve and gradually increase

the pressure to 0.5MPa.

CAUTION

Only use nitrogen for flushing. Using carbon dioxide risks leaving

condensation in the piping. Oxygen, air, refrigerant, flammable gases

and toxic gases must not be used for flushing. Use of such gases

may result in fire or explosion.