Indoor/Outdoor Unit Connection Finishing And; Flaring Work - Mitsubishi Electric MFZ-KA25VA Installation Manual

5. INDOOR/OUTDOOR UNIT CONNECTION FINISHING AND TEST RUN
INSTALLATION INFORMATION FOR THE AIR CONDITIONER WITH R410A
REFRIGERANT
• This room air conditioner adopts an HFC refrigerant (R410A) which will never destroy the ozone layer.
• Pay particular attention to the following points, though the basic installation procedure is same as that for
R22 air conditioners.
1 As R410A has a working pressure approx. 1.6 times as high as that of R22, some special tools and piping
parts / materials are required. (Refer to the table below.)
2 Take sufficient care not to allow water and other contaminations to enter the R410A refrigerant during stor-
age and installation, since it is more susceptible to contaminations than R22.
3 For refrigerant piping, use clean, pressure-proof parts / materials specifically designed for R410A.
4 Composition change may occur in R410A since it is a mixed refrigerant. When charging, charge liquid refrig-
erant to prevent composition change.
5-1 TOOLS DEDICATED FOR THE AIR CONDITIONER WITH R410A RE-
FRIGERANT
The following tools are required for R410A refrigerant. Some R22 tools can be substituted for R410A tools.
The diameter of the service port on the stop valve in outdoor unit has been changed to prevent any other
refrigerant being charged into the unit. (Cap size has been changed from 7/16 UNF with 20 threads to 1/2 UNF
with 20 threads.)
R410A tools Can R22 tools be used?
Gauge manifold No
Charge hose No
Gas leak detector No
Torque wrench Yes
Flare tool Yes
Flare gauge New
Vacuum pump adaptor New
Electronic scale for re-
New
frigerant charging
No: Not substitutable for R410A Yes: Substitutable for R410A
5-2

FLARING WORK

• Main cause of gas leakage is defect in flaring work.
Carry out correct flaring work in the following procedure.
1. Pipe cutting
• Cut the copper pipe correctly with pipe cut-
ter.
2. Burrs removal
• Completely remove all burrs from the cut cross
section of pipe.
• Put the end of the copper pipe to downward
direction as you remove burrs in order to avoid
to let burrs drop in the piping.
Description
R410A has high pressures beyond the measurement range of existing
gauges.
Port diameters have been changed to prevent any other refrigerant from
being charged into the unit.
Hose material and cap size have been changed to improve the pressure
resistance.
Dedicated for HFC refrigerant.
1/4 and 3/8
Clamp bar hole has been enlarged to reinforce the spring strength in the
tool.
Provided for flaring work (to be used with R22 flare tool).
Provided to prevent the back flow of oil. This adapter enables you to use
existing vacuum pumps.
It is difficult to measure R410A with a charging cylinder because the refrig-
erant bubbles due to high pressure and high-speed vaporization.
No good
Good
Tilted
Copper
90°
pipe
Copper pipe
Burr
Spare
reamer
Pipe cutter
3. Putting nut on
• Remove flare nuts attached to indoor and outdoor units,
then put them on pipe having completed burr removal.
(not possible to put them on after flaring work)
• Flare nut for R410A pipe differs from R22 pipe.
Refer to the following table for detail.
mm
ø6.35
ø9.52
ø12.7
4. Flaring work
• Carry out flaring work using flaring tool as shown below.
Flaring tool
Clutch type
Wing nut type
Flare tool for
Outside
R410A clutch type
diameter
ø6.35 mm 0 to 0.5
ø9.52 mm 0 to 0.5
ø12.7 mm 0 to 0.5
• Firmly hold copper pipe in a die in the dimension shown in the table above.
5. Check
• Compare the flared work with figure below.
• If flare is noted to be defective, cut off the flared section and do flaring work again.
Uneven Burred
9
R410A
17
22
26
A
York
Die
Die
Copper pipe
Copper pipe
Flare nut
A (mm)
Conventional flare tool
Clutch type Wing nut type
1.0 to 1.5 1.5 to 2.0
1.0 to 1.5 1.5 to 2.0
1.0 to 1.5 1.5 to 2.0
Inside is shining without any
Smooth all around
scratches.
Even length
all around
Flare nut
Copper pipe