Refrigeration Charge & Pipe-Work; Piping Design - Rinnai DO-SC18Z91 Operation & Installation Manual

6. REFRIGERATION CHARGE & PIPE-WORK
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Both indoor and outdoor units come delivered under positive pressure
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The outdoor unit is charged with sufficient R410a refrigerant for an interconnecting pipe run
WARNING
of 15m actual length
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The indoor unit is pressurised with 400kPa to 700kPa dry nitrogen
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Pipe end blanking plates must not be removed until the installer is sure the plates are not
under positive pressure.
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A suction accumulator has been fitted in the outdoor units
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Read all instructions and notes below before starting installation
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Use new, clean and sealed refrigeration grade pipe suitable for R410a
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Keep pipe ends sealed, both before and during installation, to avoid entry of moisture
CAUTION •
Suspend pipes with hangers or straps and seal openings around pipe penetrations with
flexible material.
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Consider pipe expansion and leave space between pipes and adjacent structures
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Use brazing shields where required
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When brazing in the vicinity of valves likely to be affected by heat, they shall be lagged with
a wet cloth
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All brazing operations must be completed with a small steady stream of nitrogen passing
through the pipe-work to limit scale build up and moisture contamination
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Never use the unit compressor as a vacuum pump
6.1

PIPING DESIGN

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Pipe-work shall be installed in a manner which prevents drainage of liquid into the compressor and ensures
adequate oil return
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Pipe insulation should be nitrile rubber, 13mm thick for pipes up to and including 20mm diameter and 19mm
thick for pipes above 20mm in diameter
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It is generally necessary to insulate the suction pipe only. However, it is recommended the liquid line pipe also
be insulated where it is exposed to direct sunlight or if located in hot surroundings such as ceiling void, or
buried underground
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Pipes should be run as directly as possible between indoor and outdoor units
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If the indoor coil is located above the condensing unit the suction line shall have a loop at the evaporator outlet
to prevent refrigerant drainage into the compressor during off cycle
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If the evaporator is located below the condensing unit, then the suction riser shall be U-Trapped at 3m above
ground level
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Avoid burying pipes below ground. If necessary, they shall be insulated and encased in a PVC pipe, sealed at
both ends where the pipe exits above ground. The buried distance shall not exceed 5 metres and a liquid line
solenoid valve, interlocked with the compressor, shall be located adjacent to the indoor unit
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Care should be taken if running pipe-work within wall cavities as this may lead to transmission of refrigerant
noise into the occupied space. The use of mufflers or oil separator can help reduce potential pulsation in the
discharge line
Brivis 46 ICE Fixed Speed OIM