6. SYSTEM DESIGN
[Installation precautions]
Contents Countermeasures (Reference)
When inside 
the ceiling 
is high 
temperature 
and high 
humidity
When the indoor unit is installed where the 
inside of the ceiling is 30°C (86°F) RH80% 
or greater, the dew point temperature of the 
outer perimeter may become higher than the 
cabinet surface temperature and moisture will 
condense on the surface of the cabinet and 
water drops may fall inside the room.
eer to ig.
In addition, the humidity may vary 
considerably the same as when the inside of 
the ceiling is close to hermetically sealed and 
used as the outside air intake path.
1) Add heat insulating material 
to the outside of the indoor 
unit cabinet.
*Regarding the cassette type, 
use of the “high humidity 
correspondence kit (option)” 
is recommended.
2) Strengthen the heat 
insulating material of the 
refrigerant piping and drain 
piping also
eer to ig.
3) When the humidity inside 
the ceiling changes 
considerably, install a 
ventilation port
Contents Countermeasures (Reference)
When using 
an external 
duct
When using an external duct to take in new 
fresh air, etc., condensation may form on 
the surface of the duct due to the effect of 
the outside air temperature and the humidity 
inside the ceiling.
1) Always perform heat 
insulation processing.
(Heat insulating material: 
Glass wool 25mm (31/32 in.) 
thick or more.)
When the 
remote 
controller 
installation site 
is bad
If the cold or warm air blown out from the air 
conditioner directly contacts the thermostat 
section of the remote controller, the outlet 
temperature of the air conditioner may be 
sensed and room temperature control will be 
different from the room temperature and “not 
cooled” or “not heated” or other trouble may 
occur. 
In addition, there is the possbility that the 
same kind of trouble may also occur when the 
remote controller is effected by direct sunlight.
1) Install the remote controller 
where it will not be directly 
exposed to the cold or hot 
air. 
2) Install the remote controller 
where it will not be directly 
exposed to sunlight or 
strong lighting.
Moist air curve
Condition which 
requires addition of 
outside heat insulation
Relative humidity 80%
Dry bulb temperature 30°C (86°F)
Fig.A
Work method when reinforcing the heat insulation 
of on-site piping
Fig.B
Slit of heat insulating 
material facing upward
Covered gas pipe 
(heat insulation 
strengthened)
Heat insulating material 
(procured at the site)
Small exposed part of 
copper pipe is desirable.
Fit tightly (purpose is 
to cover the sealant)
Binding material
Flare connection
To indoor unit
Heat insulation 
reinforcement material 
(procured at the site)
- (06 - 152) -
SYSTEM
DESIGN
SYSTEM
DESIGN