Gree GMV-Pdhm1800W4/Na-M, Installation And Operating Instruction Manual, Page: 66 / 96

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Notice for Project Installation
● Pressure Maintaining and Leak Detection
Pressure maintaining and leak detection is required during installation of connecting pipe. After connection
of connecting pipe with indoor/outdoor unit, it should be performed once again.
Operation Procedure:
（
1
）
Charge 3.8Mpa of nitrogen and maintain the pressure for 24 hours.
（
2
）
Observe if the pressure change in 24 hours.
（
3
）
If there is leakage, check screw joints of indoor/outdoor unit and each spot weld.
（
4
）
Recover or repair the leak source and maintain pressure again until it is qualified.
● Selection of Piping at Site and Heat Preservation
Wall thickness and thickness of heat insulator should conform to requirements in following table to ensure
safe project and prevent condensate attaching to heat-insulating pipe dropping.
Connecting Pipe
（
mm
）
(External diameter)
Thickness of heat insulator
（ mm ）
Φ 6.35 ≥ 10
Φ 9.52 ≥ 10
Φ 12.7 ≥ 15
Φ 15.9 ≥ 15
Φ 19.05 ≥ 15
≥Φ 22.2 ≥ 20
● Notice
◆
Only R410A can be used.
The pressure of R410A is about 1.6 times higher than that of R22.
◆
Make sure that refrigerants are charged in liquid condition.
◆
All indoor units must be with exclusive models, and please refer to Selection Manual for applicable
models.
◆
All equipments should be modified to R410 special equipment to avoid damage of ozonosphere and
green house effect.
◆
Before installation or maintenance, get ready for special tools in following table.
R410A special tool
a Manometer connecting pipe
b Filling hose
c Electronic scale for refrigerant
charging
d Torque spanner
e Flaring tool
f Vacuum pump
g Leakagemeter