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6. Refrigerant pipe and drain pipe specifications

To avoid dew drops, provide sufficient antisweating and insulating work to the refrig-
erant and drain pipes.
When using commercially available refrigerant pipes, be sure to wind commercially
available insulating material (with a heat-resisting temperature of more than 100 °C
and thickness given below) onto both liquid and gas pipes.
Insulate all indoor pipes with form polyethylene insulation with a minimum density of
0.03 and a thickness as specified in the table below.

Select the thickness of insulating material by pipe size.

If the unit is used on the highest story of a building and under conditions of

high tem-

perature and humidity, it is necessary to use pipe size and insulating material’s thick-
ness more than those given in the table above.

If there are customer’s specifications, simply follow them.

6.1. Refrigerant pipe and drain pipe specifications

6.2. Refrigerant pipe, drain pipe

[Fig. 6.2.1] (P.3)

7. Connecting refrigerant pipes and drain pipes

7.1. Refrigerant piping work

This piping work must be done in accordance with the installation manuals for both
outdoor unit and BC controller (simultaneous cooling and heating series R2).
• Series R2 is designed to operate in a system that the refrigerant pipe from an

outdoor unit is received by BC controller and branches at the BC controller to
connect between indoor units.

• For constraints on pipe length and allowable difference of elevation, refer to the

outdoor unit manual.

• The method of pipe connection is brazing connection.

Caution:

• Install the refrigerant piping for the indoor unit in accordance with the fol-

lowing.

1. Cut the tip of the indoor unit piping, remove the gas, and then remove the brazed

cap.

[Fig. 7.1.1] (P.4)

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.

Note:
• When blazing the refrigerant pipes, be sure to blaze, after covering a wet

cloth to the pipes of the units in order to prevent it from burning and
shrinking by heat.

[Fig. 7.1.2] (P.4)

• Pay strict attention when wrapping the copper piping since wrapping the

piping may cause condensation instead of preventing it.
[Fig. 7.1.3] (P.4)

Cautions On Refrigerant Piping



Be sure to use non-oxidative brazing for brazing to ensure that no foreign

matter or moisture enter into the pipe.



Be sure to apply refrigerating machine oil over the flare connection seating

surface and tighten the connection using a double spanner.



Provide a metal brace to support the refrigerant pipe so that no load is

imparted to the indoor unit end pipe. This metal brace should be provided
50 cm away from the indoor unit’s flare connection.

Warning:

Do not use refrigerant other than the type indicated in the manuals provided
with the unit and on the nameplate.

- Doing so may cause the unit or pipes to burst, or result in explosion or fire during

use, during repair, 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 mal-

functions or accidents resulting from the use of the wrong type of refrigerant.

Caution:

• Use refrigerant piping made of C1220 (Cu-DHP) phosphorus deoxidized

copper as specified in the JIS H3300 “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, shav-
ing particles, oils, moisture, or any other contaminant.

• Never use existing refrigerant piping.

- The large amount of chlorine in conventional refrigerant and refrigerator oil in

the existing piping will cause the new refrigerant to deteriorate.

• Store the piping to be used during 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 Suniso 4GS or 3GS (small amount) refrigerator oil to coat the flare and

flange connection part. (For models using R22)

• Use ester oil, ether oil or alkylbenzene (small amount) as the refrigerator oil

to coat flares and flange connections. (For models using R410A or R407C)

- The refrigerant used in the unit is highly hygroscopic and mixes with water and

will degrade the refrigerator oil.

7.2. Drain piping work

• Ensure that the drain piping is downward (pitch of more than 1/100) to the out-

door (discharge) side. Do not provide any trap or irregularity on the way.

• Ensure that any cross-wise drain piping is less than 20 m (excluding the differ-

ence of elevation). If the drain piping is long, provide metal braces to prevent it
from waving. Never provide any air vent pipe. Otherwise drain may be ejected.

• Use a hard vinyl chloride pipe VP-25 (with an external diameter of 32 mm) for

drain piping.

•     Ensure that collected pipes are 10 cm lower than the unit body’s drain port.
•     Do not provide any odor trap at the drain discharge port.
•     Put the end of the drain piping in a position where no odor is generated.
•     Do not put the end of the drain piping in any drain where ionic gases are gener-

ated.

[Fig. 7.2.1] (P.4)

Grouped piping

Pipe size

Insulating material’s thickness

6.4 mm to 25.4 mm

More than 10 mm

28.6 mm to 38.1 mm

More than 15 mm

PEFY-P·VMA(L)-E2

20·25·32·40·50

63·71·80·100·125·140