Mitsubishi Electric PUHZ-HA2 Installation Manual download pdf (Page 6)

4. Installing the refrigerant piping

4.3. Refrigerant piping (Fig. 4-3)

■ For RP35, 50

Remove the service panel D (one screw).

■ For RP60-140

Remove the service panel D (three screws) and the front piping cover A (two screws)

and rear piping cover B (two screws).

1 Perform refrigerant piping connections for the indoor/outdoor unit when the out-

door unit’s stop valve is completely closed.

2 Vacuum-purge air from the indoor unit and the connection piping.

3 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)

4 A high-performance vacuum pump is used at the stop valve service port to main-

tain a vacuum for an adequate time (at least one 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 degree

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 coolant circuits.

• If the vacuum drying is inadequate, air and water vapor remain in the coolant

circuits and can cause abnormal rise of high pressure, abnormal drop of low

pressure, deterioration of the freezing 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.

5 Use sealant to seal the ends of the thermal insulation around the pipe connection

sections to prevent water from entering the thermal insulation.

4.4. Refrigerant pipe airtight testing method (Fig. 4-4)

(1) Connect the testing tools.

• Make sure the stop valves A B are closed and do not open them.

• Add pressure to the refrigerant lines through the service port C of the liquid

stop valve D.

(2) Do not add pressure to the specified pressure all at once; add pressure little by little.

1 Pressurize to 0.5 MPa (5 kgf/cm

G), wait five minutes, and make sure the

pressure does not decrease.

2 Pressurize to 1.5 MPa (15 kgf/cm

G), wait five minutes, and make sure the

pressure does not decrease.

3 Pressurize to 4.15 MPa (41.5 kgf/cm

G) 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.

(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) Gas side of RP60-140 (Fig. 4-5)

1 Remove the cap, then turn one-quarter rotation counter-clockwise with a flat-bladed

screwdriver to complete open.

2 Check that the valves are fully open, then return the cap to its original state and

tighten it down.

(2) Liquid side of RP60-140 and Gas/Liquid side of RP35, 50 (Fig. 4-6)

1 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.

(ø6.35: Approximately 4.5 revolutions) (ø9.52: Approximately 10 revolutions)

2 Make sure that the stop valve is open completely, push in the handle and rotate

the cap back to its original position.

Refrigerant pipes are protectively wrapped for RP60-140

• 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 for RP60-140

• Use putty or sealant to seal the pipe inlet around the pipes so that no gaps remain.

(If the gaps are not closed, noise may be emitted or water and dust will enter the

unit and breakdown may result.)

A Stop valve <Liquid side>

B Stop valve <Gas side>

C Service port

D Open/Close section

4.6. Addition of refrigerant

• Additional charging is not necessary for this unit if the pipe length does not exceed 30 m.

• If the pipe length exceeds 30 m, charge the unit with additional R410A refrigerant

according to the permitted pipe lengths in the chart below.

* When the unit is stopped, charge the unit with the additional refrigerant through

the liquid stop valve after the pipe extensions and indoor unit have been

vacuumized.

When the unit is operating, add refrigerant to the gas check valve using a

safety charger. Do not add liquid refrigerant directly to the check valve.

* After charging the unit with refrigerant, note the added refrigerant amount on

the service label (attached to the unit).

Refer to the “1.5. Using R410A refrigerant air conditioners” for more information.

Fig. 4-4

Fig. 4-3

A Front piping cover

B Piping cover

C Stop valve

D Service panel

E Band radius : 100 mm-150 mm

■ RP60-140■ RP35, 50

E Local pipe

F Sealed, same way for gas side

G Pipe cover

H Do not use a wrench here.

Refrigerant leakage may result.

I Use two wrenches here.

Additional refrigerant charging amount

31 - 40 m 41 - 50 m 51 - 60 m 61 - 75 m

0.2 kg 0.4 kg ––

0.6 kg 1.2 kg ––

0.6 kg 1.2 kg 1.8 kg 2.4 kg

Model

RP35, 50

RP60, 71

RP100-

140

Permitted

pipe

length

-50 m

-75 m

Permitted

vertical

difference

-30 m

(1)

Fig. 4-6Fig. 4-5

(2)

A Valve

B Unit side

C Operation section

D Cap

E Local pipe side

F Pipe cover

G Service port

H Wrench hole

I Double spanner section

(Do not apply a spanner other than to this sec-

tion. Doing so would cause coolant leaks.)

J Seal section

(Seal the end of the heat insulation material at

the pipe connection section with whatever seal

material you have on hand so that water does

not infiltrate the heat insulation material.)

K Handle

• Be careful when installing multiple units. Connecting to an incorrect indoor unit can

lead to abnormally high pressure and have a serious effect on operation perform-

ance.

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Mitsubishi Electric PUHZ-HA2 Installation Manual Page 6

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