Mitsubishi Electric PUHZ-SW50VHA Service Manual page 6

2-3. PRECAUTIONS WHEN REUSING EXISTING R22 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 dryer.
• If the diameter of the existing pipes is different from the specified diameter, refer to technological 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 heat pump can operate.
▼
After operating the cooling system for about 30
minutes, do a pump down work.
▼
Disconnect the existing heat pump from the
pipes.
▼
Attach the new heat pump
▼
Perform the airtight test, vacuum air purging,
additional refrigerant charging (if necessary),
and gas leak check.
▼
Test run
2-4. PRECAUTIONS FOR SALT PROOF TYPE "-BS" MODEL
Although "-BS" model has been designed to be resistant to salt damage, observe the following precautions to maintain the
performance of the unit.
1. Avoid installing the unit in a location where it will be exposed directly to seawater or sea breeze.
2. If the cover panel may become covered with salt, be sure to install the unit in a location where the salt will be washed away by
rainwater. (If a sunshade is installed, rainwater may not clean the panel.)
3. To ensure that water does not collect in the base of the outdoor unit, make sure that the base is level, not at angle. Water
collecting in the base of the outdoor unit could cause rust.
4. If the unit is installed in a coastal area, clean the unit with water regularly to remove any salt build-up.
5. If the unit is damaged during installation or maintenance, be sure to repair it.
6. Be sure to check the condition of the unit regularly.
7. Be sure to install the unit in a location with good drainage.
(2) Cautions for refrigerant piping work
New refrigerant R410A is adopted for replacement inverter series. Although the refrigerant piping work for R410A 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 R410A is 1.6 times higher than that of R22, their sizes of flared sections and flare nuts are different.
1 Thickness of pipes
Because the working pressure of R410A 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
diameter (mm)
dimensions (in)
1/4
3/8
1/2
5/8
3/4
OCH525C
Measure the existing pipe thickness and
check for damage.
• If the existing heat pump cannot operate, use
a refrigerant recovery device to collect the refrigerant.
• Use new pipes for SW40–50 models.
Thickness (mm)
Outside
R410A
6.35 0.8
9.52 0.8
12.70 0.8
15.88 1.0
19.05 —
The existing pipe thickness does not meet
specifications or the pipes are damaged.
The existing pipes cannot be reused.
Use new pipes.
R22
0.8
0.8
0.8
1.0
1.0
6
▼