Design and Technical Manual

6. SYSTEM DESIGN
CAUTION
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Keep the "piping limitation" for correct operation.
Allowable height difference:
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If the height difference between the indoor unit and outdoor unit is larger than the allowable value:
The pressure loss will be larger → Insufcient cooling and heating
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The refrigerant in liquid pipe will ush → Refrigerant ow noise generate at indoor unit
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The refrigerant oil will not return → Insufcient refrigerant oil resulting in compressor damage
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If the height difference between indoor unit is larger than the allowable value:
The refrigerant ow balance will be poor → Insufcient cooling and heating (poor balance)
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Refrigerant oil will collect in the piping or non-operating indoor units
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→ Insufcient refrigerant oil resulting in compressor damage
Pipe length:
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If the pipe length is longer than prescribed:
The pressure loss will be larger → Insufcient cooling and heating
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Too much refrigerant will be charged → Liquid backs up resulting in compressor damage
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The refrigerant oil will not return → Insufcient refrigerant oil resulting in compressor damage
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Pipe size:
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If the pipe size is larger than designated size:
The refrigerant ow velocity will drop. Refrigerant oil will not return to the outdoor unit.
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→ Insufcient refrigerant oil resulting in compressor damage
The refrigerant in liquid pipe will ush easily → Insufcient cooling and heating
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If the pipe size is smaller than designated size:
The refrigerant circulation volume will drop → Insufcient cooling and heating
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The pressure loss will be larger → Insufcient cooling and heating
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Indoor unit connected capacity:
z
If the indoor unit connected capacity is larger than the system capable capacity:
Insufcient system performance → Insufcient cooling and heating
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When heating, refrigerant will collect in non-operating indoor units resulting in an insufcient
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refrigerant circulation volume → Insufcient cooling and heating
The refrigerant oil will not return → Compressor damage
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If the indoor unit connected capacity is too small compared to the system capacity:
The liquid return will be too great → Compressor damage
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The refrigerant will concentrate in the operating unit
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→ Continuous operation will become difcult due to triggering of the protection in response
to the pressure high-rise, etc., and noise will be generated by the refrigerant ow when
heating
- (06 - 13) -
SYSTEM DESIGN SYSTEM DESIGN