Refrigerant Piping Work; Restrictions - Mitsubishi Electric City Multi PURY-P72TNU-A-BS Manuel D'installation

9. Refrigerant piping work

Do not use any refrigerant other than the type indicated in the manuals for the unit and on the nameplate.
- Doing so will cause the unit or pipes to burst, or result in an explosion or fire during use, during repairs, or at the
time of disposal of the unit.
- It may also be in violation of applicable laws.
- MITSUBISHI ELECTRIC CORPORATION cannot be held responsible for malfunctions or accidents resulting from
the use of the wrong type of refrigerant.
After the installation has been completed, check for refrigerant leaks.
- If the refrigerant leaks, oxygen starvation may result. If the leaked refrigerant comes in contact with a heat source,
toxic gas will be generated.
Wear protective gloves when working on the unit.
- Failure to do so may result in injury.
- High-pressure pipes poses a risk of burns if touched with bare hands while the unit is in operation.
Use the following tools specifically designed for use with the specified refrigerant: Gauge manifold, charge
hose, gas leak detector, check valve, refrigerant charge base, vacuum gauge, and refrigerant recovery
equipment.
- Gas leak detectors for conventional refrigerants will not react to a refrigerant that does not contain chlorine.
- If the specified refrigerant is mixed with water, refrigerant oil, or another refrigerant, the refrigerant oil will deteriorate
and the compressor will malfunction.
Do not use existing refrigerant piping.
- The old refrigerant and refrigerant oil in the existing piping contain a large amount of chlorine, which will cause the
refrigerant oil in the new unit to deteriorate and cause the compressor to malfunction.

9-1. Restrictions

・Existing refrigerant piping must not be used because the design pressure for systems using R410A is higher than that for systems using other
types of refrigerants.
・Do not install outdoor unit piping when it is raining.
・Do not use special detergents for washing piping.
・Always observe the restrictions on refrigerant piping (such as pipe size, pipe length, and vertical separation distance) to prevent equipment failure
or a decline in heating/cooling performance.
・Do not install solenoid valves to prevent oil backflow and compressor start-up failure.
・Do not install a sight glass because it may show improper refrigerant flow. If a sight glass is installed, inexperienced technicians that use the glass
may overcharge the refrigerant.
・The pipe from multiple outdoor units must be installed so that oil will not accumulate in the pipe under certain conditions. Refer to the figures
below for details.
* Small dots in the figures indicate branching points.
Ⓐ To a BC controller
(1) The pipe from the outdoor units must be inclined downward to the indoor unit side. In the figure on the right, because the pipe is inclined
upward, the oil in the pipe accumulates when Unit 1 is in operation and Unit 2 is stopped.
Unit 1 Unit 2
Ⓐ
WT09106X03
Unit 1 Unit 2
Ⓐ
GB-16