Gree Ultra Heat GMV Multi VRF Heat Recovery Series Service Manual page 162

Ultra Heat GMV VRF Technical Service Manual_Heat Recovery Serial
Note: Keep wiring identical to factory installation. Control varies with compressors. Wrong wiring or
inverse connection of the compressors may cause damage to units.
Cautions on replacement of compressors:
① Before installing new compressors, remove the sealing rubbers and weld the compressors with
corresponding pipes. During welding, charge nitrogen into the pipes. Since compressors' suction and
discharge pipes are made of copper plated steels, you need to prepare special welding rods (containing
5% or more silver). Welding clearance should be controlled within 0.1~0.3mm (0.0039inch~0.0118inch),
avoiding blockage or loose welding. During welding, control pipe openings from being over-heated.
② After the pipeline system is welded, use special supports and bolts to fix the compressors,
ensuring stability of the compressors during running.
③ Power lines of the compressors should be wired following the factory installation. You can refer
to the wiring diagram. Phase sequence error and inverse connection of compressors are not allowed. In
particular, if there are two inverter compressors that need replacement, pay attention to wiring. Control
varies with compressors. Inverse connection of the compressors may cause damage to units.
Step 11: System check.
(1) Check welding joints for abnormalities.
(2) Charge nitrogen into the system for leakage detection. If you are maintaining ODU and the IDU
system is normal, you can charge nitrogen into the ODU system only. Note that nitrogen should be
charged from both the high pressure side and low pressure side. You are advised to charge through all
valves. Nitrogen pressure should be larger than 20 kgf. Then, charge soapsuds into the system and
check specially the weld joints for leakage.
(3) Finally, charge nitrogen into the system again for pressure check. Close all valves and keep
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