Mitsubishi Heavy Industries TC-PSA-25W-E Technical Manual Download

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'12 • SRK-T

-126

'09•SRK-DB-087D

Wires for connecting indoor

and outdoor units

Exterior tape

Gas piping

Insulation

Liquid piping

Band (accessory)

Pipe cover (accessory)

7) Heating and condensation prevention

(1) Dress refrigerant pipes (both gas and liquid pipes) for heat insulation and prevention of dew condensation.

●

Improper heat insulation/anti-dew dressing can result in a water leak or dripping causing damage to household effects, etc.

(2) Use a heat insulating material that can withstand 120

℃

or a higher temperature. Poor heat insulating capacity can cause heat insulation problems or cable

deterioration.

●

All gas pipes must be securely heat insulated in order to prevent damage from dripping water that comes from the condensation formed on them during a cooling operation

or personal injury from burns because their surface can reach quite a high temperature due to discharged gas flowing inside during a heating operation.

●

Wrap indoor units’ flare joints with heat insulating parts (pipe cover) for heat insulation (both gas and liquid pipes).

●

Give heat insulation to both gas and liquid side pipes. Bundle a heat insulating material and a pipe tightly together so that no gaps may be left between them and wrap them

together with a connecting cable by a dressing tape.

●

Both gas and liquid pipes need to be dressed with 20 mm or thicker heat insulation materials above the ceiling where relative humidity exceeds 70%.

CAUTION

Do not apply force beyond proper fastening torque in tightening the flare nut.

Fix both liquid and gas operation valves at the valve main bodies as illustrated on the right, and then fasten

them, applying appropriate fastening torque.

Tightening angle (

)

Tightening torque (N·m)

6.35 (1/4")

9.52 (3/8")

〜

150
200

Use a torque wrench. If a torque wrench is

not available, fasten the flare nut manually

first and then tighten it further, using the

left table as a guide.

Recommended length of a tool handle (mm)

Operation valve size (mm)

5) Air tightness test

①

Although outdoor and indoor units themselves have been tested for air tightness at the factory, check the connecting pipes after the installation work for air tightness

from the operation valve’s check joint equipped on the outdoor unit side. While conducting a test, keep the operation valve shut all the time.

a) Raise the pressure to 0.5 MPa, and then stop. Leave it for five minutes to see if the pressure drops.

b) Then raise the pressure to 1.5 MPa, and stop. Leave it for five more minutes to see if the pressure drops.

c) Then raise the pressure to the specified level (4.15 MPa), and record the ambient temperature and the pressure.

d) If no pressure drop is observed with an installation pressurized to the specified level and left for about one day, it is acceptable. When the ambient Temperature fall

℃

, the pressure also fall approximately 0.01 MPa. The pressure, if changed, should be compensated for.

e) If a pressure drop is observed in checking e) and a) – d), a leak exists somewhere. Find a leak by applying bubble test liquid to welded parts and flare joints and

repair it. After repair, conduct an air-tightness test again.

②

In conducting an air-tightness test, use nitrogen gas and pressurize the system with nitrogen gas from the gas side. Do not use a medium other than nitrogen gas

under any circumstances.

Gas side

operation valve
Check joint

Press

urize

Clos

Outdoor unit

Indoor unit

＜

Work flow

＞

6) Evacuation