Mitsubishi Heavy Industries FDT28KXE6A Service Manual page 164

⑤Duck Work (continued)
3. The air conditioning unit main body is not equipped with air filters. Incorporate air filters in
an air intake grille, which will facilitate the cleaning of air filters.
4. In the case of a rear-intake type with duct and a rear-intake ceiling-return type installation,
be sure to provide a 350 mm x 1300 mm inspection opening right beneath the unit's fan side
bottom plate to permit servicing of the unit as illustrated in installation geometries. In the case of
an underside-intake type with duct and underside-intake ceiling-return type, provide an intake
opening right beneath the unit's fan side bottom plate so that it will serve as an inspection
opening as well. Also see to its dimensions so that the intake opening will be made to 350 mm x
1300 mm.
5. Take care to install a duct horizontally in connecting the unit with a diffuser.
6. When a canvas duct is used for either intake or outlet duct, install it with care so that it may
not get flattened.
7. Select a desirable diffuser position and diffuser form to ensure the distribution of winds
throughout the room and use a diffuser employing a structure that provides the capability to
regulate winds.
8. Install the air conditioning unit main body via vibration-isolating rubbers to prevent vibrations
from propagating directly from the air conditioning unit main body to the ceiling and slab.
9. Secure at least 0.15m for the opening of an air intake.
2
10. Never fail to heat-insulate the ducts to prevent condensation on their surfaces.
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 R410 refrigerant.
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.
※ I ncomplete 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
φ 6.35
14 ~ 18
φ 9.52
34 ~ 42
φ 12.7
49 ~ 61
⑦Drain pipe
Caution
● Install the drain pipe according to the installation manual in order to drain properly.
Imperfection in draining may cause flood indoors and wetting the household goods, etc.
Do not put the drain pipe directly into the ditch where toxic gas such as sulfur, the other harmful and
●
inflammable gas is generated. Toxic gas would flow into the room and it would cause serious
damage to user's health and safety (some poisoning or deficiency of oxygen). In addition, it may
cause corrosion of heat exchanger and bad smell.
● Connect the pipe securely to avoid water leakage from the joint.
● Insulate the pipe properly to avoid condensation drop.
● Check if the water can flow out properly from both the drain outlet on the indoor unit and the end
of the drain pipe after installation.
● Make sure to make descending slope of greater than 1/100 and do not make up-down bend and/or trap
in the midway. In addition, do not put air vent on the drain pipe. Check if water is drained out properly
from the pipe during commissioning. Also, keep sufficient space for inspection and maintenance.
Strap (Accessory) Pipe cover (Accessory)
The thickness of insulation should be 20mm or more.
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⑦Drain pipe (continued)
Work procedure
1. Insert the supplied drain hose (the end made of soft PVC) to the step of the drain socket on the indoor unit
and fix it securely with the clamp. Attach the hose clamp to the drain hose around 10mm from the end.
●Do not apply adhesives on this end.
●Do not use acetone-based adhesives to connect the drain socket.
Stage difflernce part
Drain socket
Drain hose
Fasten the screw securely
Hose clamp Drain hose
Drain socket
Metal plate
10mm
2. Prepare a joint for connecting VP-20 pipe, adhere and connect the joint to the drain hose
(the end made of rigid PVC), and adhere and connect VP-20 pipe (prepare on site).
※As for drain pipe, apply VP-20 made of rigid PVC which is on the market.
● Make sure that the adhesive will not get into the supplied drain hose.
It may cause the flexible part broken after the adhesive is dried up and gets rigid.
● T he flexible drain hose is intended to absorb a small difference at the unit or installation
of drain pipes. Intentional bending, expanding may cause the flexible hose broken and
water leakage.
3. Make sure to make descending slope of greater than 1/100 and do not make up-down bend
and/or trap in the midway.
●Pay attention not to give stress on the pipe on the indoor unit side, and support and fix
the pipe as close place to the unit as possible when connecting the drain pipe.
●Do not set up air vent.
Supporting fixture Supporting metal
1.5m~2m
Air vent
Insulation material
Descending slope greater than 1/100
●When sharing a drain pipe for more than
one unit, lay the main pipe 100mm
below the drain outlet of the unit. In
addition, select VP-30 or bigger size for
main drain pipe.
4. Insulate the drain pipe.
● B e sure to insulate the drain socket and rigid PVC pipe installed indoors otherwise it may
cause dew condensation and water leakage.
※ After drainage test implementation, cover the drain socket part with pipe cover (small size), then
use the pipe cover (big size) to cover the pipe cover (small size), clamps and part of the drain
hose, and fix and wrap it with tapes to wrap and make joint part gapless.
Drain up
● The position for drain pipe outlet can be raised up to 600mm above the ceiling. Use elbows for
installation to avoid obstacles inside ceiling. If the horizontal drain pipe is too long before vertical pipe,
the backflow of water will increase when the unit is stopped, and it may cause overflow of water from
the drain pan on the indoor unit. In order to avoid overflow, keep the horizontal pipe length and offset of
the pipe within the limit shown in the figure below.
290~325mm
Drain hose
Joint for VP20 (Prepare on site)
Drain test
1. Conduct a drainage test after completion of the electrical work.
2. During the trial, make sure that drain flows properly through the piping and that no water
leaks from connections.
3. In case of a new building, conduct the test before it is furnished with the ceiling.
4. Be sure to conduct this test even when the unit is installed in the heating season.
Procedures
1. Supply about 1000 cc of water to the unit through the air outlet by using a feed water pump.
2. Check the drain while cooling operation.
Pour water in the drain pan with a siphon.
Drain pan
Pouring water hose
Remove this pipe bracket from the unit.
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Pipe cover (large) (For insulation)
(Accessory)
VP20 joint (Prepare on site)
Unit
Drain hose
VP20 (Prepare on site)
Adhesion
(Accessory)
Clamp (Accessory)
Pipe cover (For insulation)
Drain socket
(Prepare on site)
Pipe cover (small)
(For insulation) (Accessory)
Over 20mm
Trapped air will
No bump
generate noises.
No trap
Not touching
the water
As wide as possible
(about100mm)
VP-30 or bigger
Descending slope greater than 1/100
Right overhead
Attached drain
hose clamp
Pour water into a
convex joint
Drain
Unit
piping
Drain situation can be checked with
transparent socket.
If the electrical work has not been completed, connect a convex
joint in the drain pipe connection to provide a water inlet.
Then, check if water leaks from the piping system and that
drain flows through the drain pipe normally.
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