449
Fresh Air Type 
Indoor Unit
7. Cautions in Installation of Air Return Pipe & Exhaust Pipe
 ■ It is recommended to use the blast pipes, which can be anti-condensation 
and absorb sound. (purchased at local shops)
 ■ Complete the installation of the blast pipes before tting up the suspended 
ceiling.
 ■ Heat insulation should be made for the blast pipes.
 ■ The special exhaust port should be arranged at the place where the air is 
distributed evenly.
 ■ An inspection hole should be left on the surface of the ceiling for future 
maintenance.
8. Examples for Bad Installation
 ■ The unit is not equipped with the air return pipe and the inner side of the suspending ceiling is used as the blast 
pipe, causing the humidity increasing due to irregular air mass, strong wind or sunlight from the outside world. 
 ■ There might be condensate dropping down at the outer side of the blast pipe. The humidity is high, even if the 
inner side of the suspended ceiling isn't used as a blast pipe in new concrete buildings. At this time, the whole 
body should use the thermo wool for heat preservation (the thermo wool can be packed with a steel wire). 
 ■ It is operated under the conditions beyond the limits, leading to the overload of the compressor.
 ■ Affected by the capacity of the exhaust fan, and the strong wind and wind direction in the outer ue, when the 
blowing quantity of the air conditioner exceeds the limits, the drained water of the heat exchanger will overow, 
causing water leakage.
Piping Materials & Heat Insulating Materials
As to prevent condensation, heat insulating treatment should be 
performed. The heat insulating treatment for piping should be 
done respectively.
Piping 
Material
Hard PVC tube 
VP31.5mm (inner bore)
Heat 
Insulating 
Material
Vesicant polythene 
thickness: over 7mm
Pipe Length & Height Difference
9. Refrigerant Pipe
Please refer to the attached manual of outdoor units.
Example of bad installation
Exhaust fan
Blast pipe
Special exhaust port
Positioning with bolt
Air
Air