Mitsubishi Electric FDT125VNVF Technical Manual page 232

⑤Duct Work
①A corrugated board (for preventing sputtering) is attached to the main body of the air conditioner
(on the outlet port). Do not remove it until connecting the duct.
●An air filter can be provided on the main body of the air conditioner (on the inlet port). Remove
it when connecting the duct on the inlet port.
② Blowout duct
●Use rectangular duct to connect with unit.
Duct size for each unit is as shown below.
Single type 50
Multi type 22-56
A 682
B 172
B
●Duct should be at their minimum length.
●We recommend to use sound and heat insulated duct to prevent it from condensation.
●Connect duct to unit before ceiling attachment.
③ Inlet port
●When shipped the inlet port lies on the back.
●When connecting the duct to the inlet port, remove the air filter if it is fitted to the inlet port.
●When placing the inlet port to carry out suction from the bottom side, use the following
procedure to replace the suction duct joint and the bottom plate.
●Remove the screws which fasten the
bottom plate and the duct joint on the
nlet port side of the unit.
●Fit the duct join with a screw; fit the bottom plate.
●Make sure to insulate the duct to prevent dewing on it.
④Install the specific blowout duct in a location where the air will
circulate to the entire room.
●Conduct the installation of the specific blowout hole and the
connection of the duct before attaching them to the ceiling.
●Insulate the area where the duct is secured by a band for dew
condensation prevention.
⑤Make sure provide an inspection hole on the ceiling. It is indispensable to service electric
equipment, motor, functional components and cleaning of heat exchanger.
Air conditioner main unit
Blow outlet
Blowout duct
(optional or marketed item)
Suction grille
(option)
Bad example of duct work
①If a duct is not provided at the suction 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 against the out door air louver, weather (rainy day) and others.
a)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 structure, especially immedi-
ately after the construction, humidity tends to rise even if the space over the ceiling is not
substituted 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 the glass wool in place.)
b)It may run out the allowable limit of unit operation (Example: When outdoor air temperature
is 35°C DB, suction air temperature is 27°C WB) and it could result in such troubles as
compressor overload, etc..
c)There is a possibility that the blow 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 fall to reach the drain pan but leak outside
(Example: drip on to the ceiling) with consequential water leakage in the room.
②If vibration damping is not conducted between the unit and the duct, and between the unit and
the slab, vibration will be transmitted to the duct and vibration noise may occur. Also, vibration
may be transmitted from the unit to the slab. Vibration damping must be performed.
Bad example of duct work
For ventilation
UNIT: mm
60-71 100-140
71-90 112-140
882 1202
172 172
A
●Replace the removed bottom plate
and duct joint.
Secure with a band, etc.
Blowout
duct
Ceiling suriace
Suction duct
Suction hole
(marketed item)
(marketed item)
(with air filter)
Inspection hole
Suction grille
(Locality)
Louver to
outdoor air
⑤Duct Work (continued)
Connecting the air intake/vent ducts
①Fresh Air Intake
[for air intake duct only]
○Use the side fresh air intake hole, or supply
through a part of the suction duct.
[for simultaneous air intake/vent]
○Intake air through the suction duct.
(the side cannot be used)
②Air Vent
○Use the side air vent hole.
(always use together with the air intake)
○Insulate the duct to protect it from dew condensation.
⑥Refrigerant pipe
Caution
●Use the new refrigerant pipe.
When re-using the existing pipe system for R22 or R407C, pay attention to the following items.
・Change the flare nuts with the attached ones (JIS category 2), and reprocess the flare parts.
・Do not use thin-walled pipes.
●Use phosphorus deoxidized copper alloy seamless pipe (C1220T specified in JIS H3300) for refrigeration pipe installation.
In addition, make sure there is no damage both inside and outside of the pipe, and no harmful
substances such as sulfur, oxide, dust or a contaminant stuck on the pipes.
●Do not use any refrigerant other than R410A.
Using other refrigerant except R410A (R22 etc.) may degrade inside refrigeration oil. And air getting into
refrigeration circuit may cause over-pressure and resultant it may result in bursting, etc.
●Store the copper pipes indoors and seal the both end of them until they are brazed in order to avoid any dust, dirt or
water getting into pipe. Otherwise it will cause degradation of refrigeration oil and compressor breakdown, etc.
●Use special tools for R410A refrigerant.
Piping work
Refrigerant pipe
250mm
(Section where attached
in a straight line)
Work procedure
1. Remove the flare nut and blind flanges on the pipe of the indoor unit.
※ Make sure to loosen the flare nut with holding the nut on pipe side with a spanner and giving torque to the
nut with another spanner in order to avoid unexpected stress to the copper pipe, and then remove them.
(Gas may come out at this time, but it is not abnormal.)
● Pay attention whether the flare nut pops out. (as the indoor unit is sometimes pressured.)
2. Make a flare on liquid pipe and gas pipe, and connect the refrigeration pipes on the indoor unit.
※Bend the pipe with as big radius as possible and do not bend the pipe repeatedly. In addition,
do not twist and crush the pipes.
※Do a flare connection as follows:
● Make sure to loosen the flare nut with holding the nut on pipe side with a spanner and giving
torque to the nut with another spanner in order to avoid unexpected stress to the copper
pipe, and then remove them.
● When fastening the flare nut, align the refrigeration pipe with the center of flare nut, screw
the nut for 3-4 times by hand and then tighten it by spanner with the specified torque
mentioned in the table below. Make sure to hold the pipe on the indoor unit securely by a
spanner when tightening the nut in order to avoid unexpected stress on the copper pipe.
3. Cover the flare connection part of the indoor unit with attached insulation material after a gas
leakage inspection, and tighten both ends with attached straps.
●Make sure to insulate both gas pipes and liquid pipes completely.
※ Incomplete insulation may cause dew condensation or water dropping.
4. Refrigerant is charged in the outdoor unit.
As for the additional refrigerant charge for the indoor unit and piping, refer to the installation
manual attached to the outdoor unit.
Pipe diameter Tightening torque N·m
6.35
9.52
12.7
15.88
19.05 100 to 120
231
- -
'12 • PAC-T-174
Side fresh air intake hole
Fresh air intake through the
suction duct
Air vent hole
Fresh air intake through the
suction duct
Air vent hole
Fresh air intake through the
suction duct
When conducting piping work, make sure to allow the pipes
to be aligned in a straight line for at least 250 mm, as shown
in the left illustration. (This is necessary for the drain pump
to function)
Strap (Accessory) Pipe cover (Accessory)
14 to 18
34 to 42
49 to 61
68 to 82
The thickness of insulation should be 20mm or more.
⑦Drai
Caution
● Install
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● Do no
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of the
● Make
and/o
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inspec
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●Do
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5 mm
Drain
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● Th
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and/o
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4. Insula
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