Mitsubishi Electric FDT125VNVF Technical Manual page 228

⑤Duck work
②Silencing chamber (blowout)
②Silencing chamber (blowout)
③Campus joint
⑦Heat insulation ③Campus joint ③A
Air conditioner
⑤Blowout
Suction
main frame
inlet
hole
⑥Inspection hole
①(with air filter)
(600□)
①Air filters are not provided with the main frame of the air conditioner. Assemble on to the suction
grill which can be cleaned easily.
②Fit the silencing chamber according to the noise level tolerance inside the installation room. If it
is particularly necessary to keep the noise level low, further silencing devices is required (always
install them in offices, and conference rooms).
③In order to keep the vibration from transferring to the ceiling and the slab, use a campus joint for
the duct and a vibration proof rubber for the main frame.
④Attach an airflow adjustment damper to the connection point of the OA duct so airflow adjust-
ment may be possible after installation.
⑤For the blowing outlet, select a shape and location where air may circulate, and a structure where
airflow may be controlled.
⑥An inspection hole must be made in the ceiling surface. This is necessary for the repair and
maintenance of the electrical parts, motor and functional parts, as well as for cleaning the heat
exchanger.
⑦Insulation must be performed for the duct to prevent water condensation on the duct. The thickness
of the insulating material is 65 mm (JISA 9501).
A bad example of duct work
②
①
Atmospheric
gallery
Ventilation fan
a. Condensation occurs on the outer board of the unit and water may fall on the ceiling. Use the unit
according to the air conditions in the above table and airflow limits. In concrete constructions, high
humidity can occur in new constructions even when the attic is not used as a suction duct. In this
case, insulate the entire unit with glass wool (25 mm) (use a metal net to hold the wool).
b. Operation of the unit may exceed its limits (for example, when the temperature of the suction air is
24 °C with the outdoor temperature of 35 °C DB). In such a cases, problems such as an overload
of the compressor may occur.
c. The volume of the air blowing in may increase due to the performance of the ventilation fan and the
wind strength blowing against the atmospheric gallery. The air usage limit may be exceeded, and
the water from the heat exchanger will not be able to drain to the drain pan. Instead it will drain
outside and cause a water leak (to the ceiling).
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.
Simple setting method for duct measurement
The following shows the method when duct is used at one side of 250mm as 1Pa/m by frictional
resistance per the unit length of the duct, and in case of 250 type (single unit)/280 type (multi unit) ,
60Hz rating airflow for a example.
Air conditioning unit
4800m 3 /h
1200m /h
3
Supply (air inlet)
1200m 3 /h chamber
Airflow Duct (mm x mm)
4800m /h
3
250 x 950
(80m 3 /min)
1200m /h
3
250 x 310
(20m 3 /min)
○Calculation of duct resistance
(Simplified calculate as following table)
Straight piping port Calculate at 1Pa per 1m length to 1Pa/m
Calculate at 3 to 4 m straight pipe per 1 piece
Bending port
of binding pipe
Air outlet port Calculate at 25Pa
Chamber Calculate at 50Pa per 1 piece
Air inlet grille (with filter) Calculate at 40Pa per 1 piece
Detailed view of part A
(hanger, vibration proof)
④Airflow adjustment damper
OA
Ceiling surface
①If the suction duct is not used, and the attic is
used as a suction duct, the attic will become
extremely humid depending on the perfor-
mance of the ventilation fan, the strength of
wind blowing to the atmospheric gallery and
the climate (e.g., rainy days).
[Simplified duct dimension
selection table]
1Pa/m
Air Fillter
Duct type
Quadrangle duct
Item
Dimensions
Airflow
4800m 3 /h
-
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.
●The indoor unit pipes allow the maintenance panel to be removed. Therefore, regardless of the
piping direction, there should be a straight section of 400 mm or more.
Work procedure
1. When brazing work, perform it while cool down around the brazing port with wet towels to
prevent the overheating.
2. After check the gas leak test, install the heat insulation (prepare on site) to the brazing port of
the indoor unit.
●Be sure to perform the heat insulation both of gas side piping with liquid side piping.
※If heat insulation does not install to the pipes, dew condensation may occurs and it may
cause the water leakage.
The thickness of the heat insulation should be more than 20mm.
3. 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.
Single unit
Liquid piping φ 9.52
Type 200
φ 25.4
Gas piping
Liquid piping φ 12.7
Type 250
φ 25.4
Gas piping
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.
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.
●Do not apply adhesives on this end.
Drain socket
Indoor unit
2. Prepare a joint for connecting VP-25 pipe, adhere and connect the joint to the drain hose (the
end made of rigid PVC), and adhere and connect VP-25 pipe (prepare on site).
※As for drain pipe, apply VP-25 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.
● The flexible drain hose is intended to absorb a small difference at installation of the unit or
drain pipes. Intentional bending, expanding may cause the flexible hose broken and water
leakage.
227
-
'12 • PAC-T-174
Multi unit
Liquid piping φ 9.52 Flaring
Type 224
φ 19.05
Gas piping Flaring
Liquid piping φ 9.52 Flaring
Type 280
φ 22.22
Gas piping Flaring
Hose clamp
(Accessory)
VP-25
(Prepare on site)
Pipe cover
(For insulation)
(Prepare on site)
⑦D
3. M
an
●
●
Insu
D
●
4. In
●
Cauti
When
becom
Exam
Fixing
The p
(durin
make
illustr
unit.
H1 =
H2 =
Drain
Upon
○