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10.4.4. Refrigerant piping
Refrigerant is charged to the outdoor unit. For details, see the manual for installation work of outdoor unit.(Additional charging,
etc.)
1. Brazing for piping.
a. Execute brazing before tightening the flare nut.
b. Brazing must be executed while blowing nitrogen gas.
(This prevents generation of oxidized scale in copper pipe.)
2. When there is a lot of brazing for long piping, install a strainer at the midway of the piping.
(The strainer is locally supplied.)
3. Use clean copper pipe with inner wall surface free from mist and dust. Blow nitrogen gas or air to blow off dust in the pipe
before connection.
4. Form the piping according to its routing. Avoid bending and bending back the same piping point more than three times.
(This will result in hardening of the pipe).
5. After deforming the pipe, align centers of the union fitting of the indoor unit and the piping and tighten them firmly with
wrenches.
6. Connect pipe to the service valve or ball valve which is located below the outdoor unit.
7. After completed the piping connection, be sure to check if there is gas leakage in indoor and outdoor connection.
• Confirm the red mark of the union (thin side) is always at lower direction after connecting piping.
Vacuum drying
After completing the piping connection, execute vacuum drying for the connecting piping and the indoor unit.
The vacuum drying must be carried out by using the service ports of both the liquid and gas side valves.
10.4.5. Indoor unit drain piping
• Drain piping must have down-slope (1/50 to 1/100): be sure not to provide up-and-down slope to prevent reversal flow.
• During drain piping connection, be careful not to exert extra force on the drain port at the indoor unit.
• The outside diameter of the drain connection at the indoor unit is 32 mm.
• Be sure to perform heat insulation on the drain piping.
CAUTION Use two wrenches and tighten with regular torque.
Flare nut fastening torque N.m (kgf.cm)
ø6.35 mm 18 (180) ø12.7 mm 55 (560) ø19.05 mm 100 (1020)
ø9.52 mm 42 (430) ø15.88 mm 65 (660)
Liquid side piping Gas side piping
ø9.52 mm ø15.88 mm
Piping material: Polyvinyl chloride pipe VP-25 and pipe fittings
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