Mitsubishi Heavy Industries FDC112KXEN6 Technical Manual page 218

5 Make sure provide an inspection hole on the ceiling. It is indispensable to service electric equipment, motor, functional
components and cleaning of heat exchanger.
r Supply air port
Return air grille
(option)
6 If a duct is not provided at the return air side but it is substituted with the space over the ceiling, humidity in the space will
increase by the influence of capacity of ventilation fan, strength of wind blowing againat the outdoor air louver, weather
(rainy day) and others.
¡ Moisture in air is likely to condense over the external plates of the unit and to drip on the ceiling. Unit should be
operated under the conditions as listed in the above table and within the limitation of wind volume. When the building
is a concrete strucially immediately after the construction, humidity tends to rise if the space over the ceiling is not
substitued in place of a duct. In such occasion, it is necessary to insulate the entire unit with glass wool (25mm). (Use
a wire net or equivalent to hold glass wool in place.)
¡ It may run out the allowable limit of unit operation (Example: When outdoor air temperature is 35ºCD.B, return air
temperature is 27ºCW.B) and it could result in such troules as compressor overload, etc..
¡ There is a possibility that the supply air volume may exceed the allowable range of operation due to the capacity of
ventilation fan or strength of wind blowing against external air louver so that drainage from be heat exchanger may fail
to reach the drain pan leak outside (e.g. drip on to the ceiling) with consequential water leakage in the room.
Notice: Aspecific cover plate is available when changing the 4 spot to the 3 spot, or when changing the 3 spot to the 2 spot.
Note (1) Do not change from 2 spot to 1 spot.
Air conditioner indoor unit
w Supply air duct
(optional or marketed item)
Bad example of duct work
w
For ventilation
214
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Ceiling surface
e Return air
duct
(marketed item)
q Return air port
(marketed item)
t Inspection hole
(with air filter)
Return air grille
(Locality)
q
Louver to
outdoor air
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