Refrigerant Piping Work - Mitsubishi Electric CITY MULTI PVFY-P18 NAMU-E Installation Manual

11. Refrigerant piping work

This piping work must be done in accordance with the installation
manuals for both outdoor unit and BC controller (R2/WR2 series)
Series R2 is designed to operate in a system that the refrigerant
pipe from an outdoor unit is received by the BC controller and
branches at the BC controller to the indoor units.
For constraints on piping length and allowable difference of
elevation, refer to the design section of the engineering manual.
The method of pipe connection on the air handler is braze
connection.
Cautions of refrigerant piping
Be sure to use non-oxidative procedures for
brazing to ensure that no foreign matter or
moisture enters the piping.
ALWAYS USE A NITROGEN PURGE IN THE PIPING DURING
BRAZING
Provide proper bracing for refrigerant piping so no load is
imparted upon the connections at the air handler.
Warning:
When installing and moving the unit, do not charge it with
refrigerant other than the refrigerant specifi ed on the unit.
Mixing of a different refrigerant, air, etc. may cause the
refrigerant cycle to malfunction and result in severe
damage.
Caution:
Use refrigerant piping made of C1220 (Cu-DHP)
phosphorous deoxidized copper as specifi ed in ASTM
B280 Standard for copper and copper alloy seamless
pipes and tubes. In addition, be sure that the inner
and outer surfaces of the pipes are clean and free of
hazardous sulphur, oxides, dust/dirt, shaving particles, oils,
moisture, or any other contaminant.
Never use existing refrigerant piping.
Caution: COIL UNDER PRESSURE
Always wear safety glasses when working around
pressurized devices.
The air handlers are shipped with a nitrogen holding
charge in the coil. Carefully follow these instructions when
releasing the charge.
Caution:
following.
1. Cut the tip of the indoor unit piping, remove the gas, and then remove the
brazed cap.
Figure below
A Cut here
B Remove brazed cap
2. Pull out the thermal insulation on the site refrigerant piping, braze the unit
piping, and replace the insulation in its original position.
Wrap the piping with insulating tape.
wet cloth to the pipes of the units in order to prevent it from burning and
shrinking by heat.
Figure below
A Cool by a wet cloth
piping may cause condensation instead of preventing it.
Figure below
A Thermal insulation
C Wrap with damp cloth
E Ensure that there is no gap here
16
B Pull out insulation
D Return to original position
F Wrap with insulating tape
-Never use existing refrigerant piping.
-The large amount of chlorine in conventional refrigerant and
refrigerant oil in the existing piping will cause the new refrigerator to
deteriorate.
-Store the piping to be used during the installation indoors and keep
both ends of the piping sealed until just before brazing.
-If dust, dirt or water gets into the refrigerant cycle, the oil will
deteriorate and the compressor may fail.
-Use ester oil, ether oil or alkylbenzene (small amount) as the
refrigerant oil to coat fl ares and fl ange connections before
connecting.
-The refrigerant used in the unit is highly hydroscopic and mixes with
water which will degrade the refrigerant oil.