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2-3. PRECAUTIONS WHEN REUSING EXISTING R22/R410A REFRIGERANT PIPES
(1) Flowchart
• Refer to the flowchart below to determine if the existing pipes can be used and if it is necessary to use a filter drier.
• If the diameter of the existing pipes is different from the specified diameter, refer to technical data materials to confirm if the
pipes can be used.
The existing pipe thickness meets specifica-
tions and the pipes are not damaged.
Check if the existing outdoor unit can operate.
After operating the cooling system for about 30
minutes, do a pump down work.
Disconnect the existing outdoor unit from the
pipes.
Attach the new outdoor unit
Perform the airtight test, vacuum air purging,
additional refrigerant charging (if necessary),
and gas leak check.
Test run
(2) Cautions for refrigerant piping work
New refrigerant R32 is adopted for replacement inverter series. Although the refrigerant piping work for R32 is same as for
R22, exclusive tools are necessary so as not to mix with different kind of refrigerant. Furthermore as the working pressure
of R32 is 1.6 times higher than that of R22, their sizes of flared sections and flare nuts are different.
Thickness of pipes
Because the working pressure of R32 is higher compared to R22, be sure to use refrigerant piping with thickness shown
below. (Never use pipes of 0.7 mm or below.)
Diagram below: Piping diameter and thickness
Nominal
dimensions (in)
1/4
3/8
1/2
5/8
3/4
Dimensions of flare cutting and flare nut
The component molecules in HFC refrigerant are smaller compared to conventional refrigerants. In addition to that, R32
is a refrigerant, which has higher risk of leakage because its working pressure is higher than that of other refrigerants.
Therefore, to enhance airtightness and strength, flare cutting dimension of copper pipe for R32 has been specified sepa-
rately from the dimensions for other refrigerants as shown below. The dimension B of flare nut for R32 also has partly
been changed to increase strength as shown below. Set copper pipe correctly referring to copper pipe flaring dimensions
for R32 below. For 1/2 and 5/8 inch pipes, the dimension B changes.
Use torque wrench corresponding to each dimension.
Dimension A
Flare cutting dimensions
Nominal
Outside
dimensions (in)
diameter (mm)
1/4
6.35
3/8
9.52
1/2
12.70
5/8
15.88
3/4
19.05
OCH809A
Measure the existing pipe thickness and
check for damage.
• If the existing outdoor unit cannot operate, use a
refrigerant recovery device to collect the refrigerant.
• In case existing pipes were used for gas or oil
heat pump systems, be sure to clean the pipes.
Outside
diameter (mm)
R32/R410A
6.35
0.8
9.52
0.8
12.70
0.8
15.88
1.0
19.05
+0
Dimension A (
)(mm)
-0.4
R32
R22
9.1
9.0
13.2
13.0
16.6
16.2
19.7
19.4
—
23.3
The existing pipes cannot be reused.
Use new pipes.
Thickness (mm)
R22
0.8
0.8
0.8
1.0
—
1.0
Flare nut dimensions
Nominal
Outside
dimensions (in)
diameter (mm)
1/4
3/8
1/2
5/8
3/4
8
The existing pipe thickness does not meet
specifications or the pipes are damaged.
Dimension B
Dimension B(mm)
R32
6.35
17.0
9.52
22.0
12.70
26.0
15.88
29.0
19.05
—
R22
17.0
22.0
24.0
27.0
36.0
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