Refrigerant Piping - Hitachi Primairy Series Installation & Maintenance Manual

INSTALLATION INSTRUCTIONS
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Refrigerant piping

1 Piping requirement
Outer diameter of pipe (mm)
Model
3.0/3.5HP
4.0/5.0/6.0/6.5HP
The shorter the refrigerant piping is, the better the performance will be. So the connecting pipe should be as short as possible.
Indoor unit
Height difference H
Max. pipe length
Model
(L)
3.0HP 30 (m)
3.5/4.0/5.0/
50 (m)
6.0/6.5HP
Refrigerant piping between indoor unit and outdoor unit
Refrigerant additional charge
The unit has been filled with refrigerant, but if exceeds 5m, additional refrigerant (R32) charge is required.
Additional refrigerant charge =(L-5)×28g/m
Oil trap
When the indoor unit is lower than outdoor unit and height is larger than 5m, set an oil trap every 5m (height difference) on suction
piping.
NOTE:
• To avoid storing too much oil in the oil trap, the oil trap should be as short as possible.
• The horizontal piping should be slope down along the refrigerant flow direction, to bring the oil back to compressor, the slope is
about 1/200 to1/250.
• In order to ensure a better cooling/heating performance, the refrigerant piping should be as short and straight as possible.
2 Piping material
1. Prepare locally-supplied copper pipes.
2. Select clean copper pipes. Make sure that there is no dust and moisture inside of the pipes. Blow the inside of the pipes with
nitrogen or dry air to remove any dust or foreign materials before connecting pipes.
3. Piping thickness and material of the pipe are shown below.
Diameter Thickness
∅6.35
∅9.52
∅12.7
∅15.88
∅19.05
12 HO2019292HA
Gas Liquid
15.88 9.52
19.05 9.52
Pipe length L
Outdoor unit
Max. height Add. refrigerant
difference (H)
15 (m)
30 (m)
Unit: mm
0.8
0.8
0.8
1.0
1.0
(Unit: mm)
(exceed 5m)
28 (g/m)
28 (g/m)
Slope: 1/200~1/250
Slope: 1/200~1/250
Oil trap
Oil trap