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PMML0140A rev.1 - 07/2009
REFRIGERANT PIPING &
REFRIGERANT CHARGE
11.4.3.TWIN AND QUAD SYSTEM INSTALLATION
Height Difference Between Indoor Units and Distributor•
Install all indoor units at the same height. When the
height difference between the indoor units due to building
construction is necessary, this should be less than 0,5
meters. Install the branch pipe at the same height of indoor
units or lower, but never higher.
Sample: Twin system
Indoor units
Smaller than
0.5 mm
Height difference between two
indoors. Smaller than 0.5m
Branch pipe
Piping size for Indoor Unit.•
The piping size for indoor unit are as follows
mm(in.)
Unit Gas piping size Liquid piping size
1.5 HP 12.7 (1/2”)
6.35 (1/4”)
2.0 HP
15.88 (5/8”)
2.5 HP 9.53 (3/8”)
Installing Distributor•
1. Install the Distributor supplied by HITACHI on request
A tee can not be installed instead of a branch pipe.
Sample: Twin System
2. Installing the Distributor.
Fix the branch pipe horizontally to the pillar, wall or ceiling.
Piping must not be xed rigidly to the wall as thermal
expansion and contraction can cause pipe fracture.
Sample: Twin System
Horizontal
To RASC unit
To indoor unit
Vertical
To indoor unit
Fixing the branch pipie to
the surface of pillar or wall
Horizontal
Horizontal
Fixing the branch pipe to
ceiling or beam
NOTE:
Fix the piping from outside of insulation or inserting -
absorber between the pipe and a xing metal.
3. Correct position of twin distributor
This is the correct position of twin Branch Pipe:
•
Up
Down
Greater
than 0.5m
Main Pipe
Refrigerant direction
Refrigerant
direction
Main Pipe
Branch pipe
This is wrong position.•
Up
Down
Main Pipe
Refrigerant
direction
Main Pipe
Branch pipeBranch pipe
Branch pipe
4. Correct position of Quad Distributor.
Install the header horizontally
•
Sample: Quad Branch pipe
Gas piping
Liquid piping
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