Mitsubishi Electric Mr. Slim PUHZ-P-YHA Serie Manuel D'installation page 6

4. Installing the refrigerant piping
Fig. 4-4
Stop valve <Liquid side>
Stop valve <Gas side>
Service port
Open/Close section
Local pipe
Seal section
(Seal the end of the heat insulation mate-
rial at the pipe connection section with
whatever seal material you have on hand
so that water does not infiltrate the heat
insulation material.)
Fig. 4-5
(1)
Fig. 4-6
Valve Double spanner section
(Do not apply a spanner other than to this section. Doing
Unit side
so would cause refrigerant leaks.)
Operation section
Seal section
Cap
(Seal the end of the heat insulation material at the pipe
Local pipe side
connection section with whatever seal material you have
Pipe cover
on hand so that water does not infiltrate the heat insula-
Service port
tion material.)
Wrench hole
Fig. 4-8
6
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Front piping cover
Piping cover
Stop valve
Service panel
Bend radius : 100 mm-150 mm
Pipe cover
Do not use a wrench here.
Refrigerant leakage may result.
Double spanner section
(Do not apply a spanner other than to this
section. Doing so would cause refrigerant
leaks.)
(2)
Fig. 4-7
* The figure to the left is an example only.
The stop valve shape, service port position,
etc., may vary according to the model.
* Turn section only.
(Do not further tighten sections and
together.)
Charge hose
Service port
4.3. Refrigerant piping (Fig. 4-4)
Remove the service panel (3 screws) and the front piping cover
and rear piping cover (2 screws).
Perform refrigerant piping connections for the indoor/outdoor unit when the out-
door unit's stop valve is completely closed.
Vacuum-purge air from the indoor unit and the connection piping.
After connecting the refrigerant pipes, check the connected pipes and the indoor
unit for gas leaks. (Refer to 4.4 Refrigerant pipe airtight testing method)
A high-performance vacuum pump is used at the stop valve service port to main-
tain a vacuum for an adequate time (at least 1 hour after reaching –101 kPa (5
Torr)) in order to vacuum dry the inside of the pipes. Always check the degree
of vacuum at the gauge manifold. If there is any moisture left in the pipe, the de-
gree of vacuum is sometimes not reached with short-time vacuum application.
After vacuum drying, completely open the stop valves (both liquid and gas) for
the outdoor unit. This completely links the indoor and outdoor refrigerant circuits.
• If the vacuum drying is inadequate, air and water vapor remain in the refriger-
ant circuits and can cause abnormal rise of high pressure, abnormal drop of
low pressure, deterioration of the refrigerant machine oil due to moisture, etc.
• If the stop valves are left closed and the unit is operated, the compressor and
control valves will be damaged.
• Use a leak detector or soapy water to check for gas leaks at the pipe connec-
tion sections of the outdoor unit.
• Do not use the refrigerant from the unit to purge air from the refrigerant lines.
• After the valve work is completed, tighten the valve caps to the correct torque:
20 to 25 N·m (200 to 250 kgf·cm).
Failure to replace and tighten the caps may result in refrigerant leakage. In
addition, do not damage the insides of the valve caps as they act as a seal to
prevent refrigerant leakage.
Use sealant to seal the ends of the thermal insulation around the pipe connec-
tion sections to prevent water from entering the thermal insulation.
4.4. Refrigerant pipe airtight testing method (Fig. 4-5)
(1) Connect the testing tools.
• Make sure the stop valves are closed and do not open them.
• Add pressure to the refrigerant lines through the service port
stop valve .
(2) Do not add pressure to the specified pressure all at once; add pressure little by
little.
Pressurize to 0.5 MPa (5 kgf/cm²G), wait 5 minutes, and make sure the pres-
sure does not decrease.
Pressurize to 1.5 MPa (15 kgf/cm²G), wait 5 minutes, and make sure the
pressure does not decrease.
Pressurize to 4.15 MPa (41.5 kgf/cm²G) and measure the surrounding tem-
perature and refrigerant pressure.
(3) If the specified pressure holds for about one day and does not decrease, the
pipes have passed the test and there are no leaks.
• If the surrounding temperature changes by 1°C, the pressure will change by
about 0.03 MPa (0.3 kgf/cm G). Make the necessary corrections.
2
(4) If the pressure decreases in steps (2) or (3), there is a gas leak. Look for the
source of the gas leak.
4.5. Stop valve opening method
The stop valve opening method varies according to the outdoor unit model. Use the
appropriate method to open the stop valves.
(1) Liquid side of stop valve (Fig. 4-6)
Remove the cap and turn the valve rod counterclockwise as far as it will go with
the use of a 4 mm hexagonal wrench. Stop turning when it hits the stopper.
(Approximately 10 revolutions)
Make sure that the stop valve is open completely and rotate the cap back to its
original position.
(2) Gas side of stop valve (Fig. 4-7)
Remove the cap, pull the handle toward you and rotate 1/4 turn in a counter-
clockwise direction to open.
Make sure that the stop valve is open comletely and rotate the cap back to its
original position.
Refrigerant pipes are protectively wrapped
• The pipes can be protectively wrapped up to a diameter of ø90 before or after
connecting the pipes. Cut out the knockout in the pipe cover following the groove
and wrap the pipes.
Pipe inlet gap
• Use putty or sealant to seal the pipe inlet around the pipes so that no gaps re-
main. (If the gaps are not closed, noise may be emitted or water and dust will
enter the unit and breakdown may result.)
Precautions when using the charge valve (Fig.4-8)
Do not tighten the service port too much when installing it, otherwise, the valve
core could be deformed and become loose, causing a gas leak.
After positioning section in the desired direction, turn section
it.
Do not further tighten sections and
Warning:
When installing the unit, securely connect the refrigerant pipes before start-
ing the compressor.
(2 screws)
of the liquid
only and tighten
together after tightening section .