
Work instructions
The existing R22 and R410A piping can be reused for
inverter R32 product installations.
WARNING
Confirming the existence of scratches or dents on
the existing pipes and confirming the reliability of
the pipe strength are conventionally referred to
the local site.
If the specified conditions can be cleared, it is
possible to update existing R22 and R410A pipes
to those for R32 models.
Basic conditions needed to reuse existing
pipes
Check and observe the presence of three conditions
in the refrigerant piping works.
1. Dry (There is no moisture inside of the pipes.)
2. Clean (There is no dust inside of the pipes.)
3. Tight (There are no refrigerant leaks.)
Restrictions for use of existing pipes
In the following cases, the existing pipes
should not be reused as they are. Clean the
existing pipes or exchange them with new pipes.
1. When a scratch or dent is heavy, be sure to use
new pipes for the refrigerant piping works.
2. When the existing pipe thickness is thinner than
the specified “Pipe diameter and thickness,” be
sure to use new pipes for the refrigerant piping
works.
• The operating pressure of R32 is high (1.6 times
that of R22). If there is a scratch or dent on the
pipe or a thinner pipe is used, the
pressure strength may be inadequate, which
may cause the pipe to break in the worst case.
* Pipe diameter and thickness (mm)
Pipe outer diameter Ø6.4 Ø9.5 Ø12.7
Thickness R32, R410A 0.8 0.8 0.8
R22
3. When the outdoor unit was left with the pipes
disconnected, or the gas leaked from the pipes and
the pipes were not repaired and refilled.
• There is the possibility of rain water or air,
including moisture, entering the pipe.
4. When refrigerant cannot be recovered using a
refrigerant recovery unit.
• There is the possibility that a large quantity of
dirty oil or moisture remains inside the pipes.
5. When a commercially available dryer is attached to
the existing pipes.
• There is the possibility that copper green rust
has been generated.
6. When the existing air conditioner is removed after
refrigerant has been recovered.
Check if the oil is judged to be clearly dierent from
normal oil.
• The refrigerator oil is copper rust green in color:
There is the possibility that moisture has mixed
with the oil and rust has been generated inside
the pipe.
• There is discolored oil, a large quantity of resi-
due, or a bad smell.
• A large quantity of shiny metal dust or other wear
residue can be seen in the refrigerant oil.
7. When the air conditioner has a history of the com-
pressor failing and being replaced.
• When discolored oil, a large quantity of residue,
shiny metal dust, or other wear residue or
mixture of foreign matter is observed, trouble
will occur.
8. When temporary installation and removal of the air
conditioner are repeated such as when leased etc.
9. If the type of refrigerator oil of the existing air
conditioner is other than the following oil (Mineral
oil), Suniso, Freol-S, MS (Synthetic oil), alkyl
benzene (HAB, Barrel-freeze), ester series, PVE
only of ether series.
• The winding-insulation of the compressor may
deteriorate.
NOTE
The above descriptions are results have been
confirmed by our company and represent our views
on our air conditioners, but do not guarantee the use
of the existing pipes of air conditioners that have
adopted R32 in other companies.
Curing of pipes
When removing and opening the indoor or outdoor
unit for a long time, cure the pipes as follows:
• Otherwise rust may be generated when moisture or
foreign matter due to condensation enters the pipes.
• The rust cannot be removed by cleaning, and new
pipes are necessary.
Placement
location Term Curing manner
Outdoors 1 month or more Pinching
Less than 1 month Pinching or taping
Indoors Every time
Are there scratches or dents on the existing pipes?
Is it possible to operate the existing air conditioner?
Was largely discolored oil or a large quantity
of remains discharged? (When the oil deteriorates,
the color of the oil changes to a muddy
or black color.)
• After the existing air conditioner is operated in cooling
mode for approx. 30 minutes or longer,* recover the
refrigerant.
• For cleaning the pipes and recovering oil
• Refrigerant recovery: Pump down method
• Remove the existing air conditioner from the piping and
carry out flushing (nitrogen pressure 0.5 MPa) to remove
any remains inside of the pipe.
Note: In case of twin pipes, also be sure to flush the
branching pipe.
Connect the indoor / outdoor units to the existing pipe.
• Use a flare nut attached to the main unit for the indoor
/ outdoor units. (Do not use the flare nut of the existing
pipe.)
• Re-machine the flare machining size to size for R32.
• (Airtight test), Vacuum dry, Refrigerant charge, Gas leak
check
Existing pipes: Cannot be used.
• Use new pipes.
Clean the pipes or use new pipes.
(If there is discharge of remains, it is judged that a
large quantity of remains are present.)
Test run
YES
YES
YES
NO
NO
NO
Nitrogen gas pressure 0.5 MPa
Piping necessary to change the are nut / machining
size due to pipe compression
1) Flare nut width: H
(mm)
Copper pipe
outer diameter Ø6.4 Ø9.5 Ø12.7
For R32, R410A 17 22 26
For R22 Same as above 24
2) Flare machining size: A
(mm)
Copper pipe
outer diameter Ø6.4 Ø9.5 Ø12.7
For R32, R410A 9.1 13.2 16.6
For R22 9.0 13.0 16.2
Becomes a little larger for R32
Do not apply refrigerator oil to the flare surface.
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