Refrigerant Pipe And Drain Pipe Specifications; Connecting Refrigerant Pipes And Drain Pipes; Refrigerant Piping Work; Refrigerant Pipe, Drain Pipe And Filling Port - Mitsubishi Electric PEH-P400 Manuel D'installation

6. Refrigerant pipe and drain pipe specifications

To avoid dew drops, provide sufficient antisweating and insulating work to the re-
frigerant and drain pipes.
When using commercially available refrigerant pipes, be sure to wind commer-
cially available insulating material (with a heat-resisting temperature of more than
100 °C and thickness given below) onto both liquid and gas pipes.
Be also sure to wind commercially available insulating material (with a form
polyethylene's specific gravity of 0.03 and thickness given below) onto all pipes
which pass through rooms.
1 Select the thickness of insulating material by pipe size.
Pipe size
6.4 mm to 25.4 mm
28.6 mm to 38.1 mm
2 If the unit is used on the highest story of a building and under conditions of
high temperature and humidity, it is necessary to use pipe size and insulating
material's thickness more than those given in the table above.
3 If there are customer's specifications, simply follow them.

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
outdoor unit.
• For constraints on pipe length and allowable difference of elevation, refer to
the outdoor unit manual.
• The method of pipe connection is brazing connection.
Cautions on refrigerant piping
s Be sure to use non-oxidative brazing for brazing to ensure that no for-
eign matter or moisture enter into the pipe.
s 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 pro-
vided 50 cm away from the indoor unit's brazing connection.
Warning:
Do not mix anything other than the specified refrigerant (R407C) into the
refrigerating cycle. Mixing air may cause the refrigerating cycle to get abnor-
mally high temperature, resulting in a burst.
Caution:
• Install the refrigerant piping for the indoor unit in accordance with the
following.
1. Remove the cap.
[Fig. 7.1.1] (P.3)
A Remove the 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.
[Fig. 7.1.2] (P.3)
A Thermal insulation
C Wrap with damp cloth
E Ensure that there is no gap here
Note:
• Pay strict attention when wrapping the copper piping since wrapping the
piping may cause condensation instead of preventing it.
* Before brazing the refrigerant piping, always wrap the piping on the main
body, and the thermal insulation piping, with damp cloths to prevent heat
shrinkage and burning the thermal insulation tubing. Take care to ensure
that the flame does not come into contact with the main body itself.
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 ester oil, ether oil or alkylbenzene (small amount) as the refrigerator
oil to coat flares and flange connections.
10
Insulating material's thickness
More than 10 mm
More than 15 mm
B Pull out insulation
D Return to original position
F Wrap with insulating tape
6.1. Refrigerant pipe and drain pipe specifi-
cations
Model
Item
Liquid pipe
Refrigerant pipe
Gas pipe
Drain pipe
6.2. Refrigerant pipe, drain pipe and filling
port
[Fig. 6.2.1] (P.3)
A Refrigerant pipe (liquid pipe)
C Drain pipe
- The refrigerant used in the unit is highly hygroscopic and mixes with water
and will degrade the refrigerator oil.
• Do not use a leak detection additive.

Additional refrigerant charge

• Take care not to allow dirt or cutting chips to enter the refrigerant pipes.
• The refrigerant pipes must be kept warm, so take particular care to insulate
between refrigerant pipes and the gas pipe located inside the indoor unit, since
the gas pipe causes condensation during cooling operation.
• When connecting the refrigerant pipes, make sure that the stop valve of the
outdoor unit is fully closed (as it was when shipped from the factory). After
connecting all the refrigerant pipes between the indoor and outdoor units, purge
air from the stop valve service port of the outdoor unit and service port of each
connecting pipe. Check that there is no air leakage from any pipe connection,
then fully open the stop valve of the outdoor unit. This will connect the refriger-
ant circuit between the indoor and outdoor units.
• The refrigerant pipes must be as short as possible.
• Flare and flange connections must be used for connection of the refrigerant
pipes.
• The indoor and outdoor units must be connected with the refrigerant pipes.
[Fig. 7.1.3] (P.3)
A Brazing B Flare joint
D Liquid pipe E Service port
G Outdoor unit
Warning:
During installation and re-installation, take care not to allow any gas or ma-
terials other than the specified refrigerant (R407C) to enter the refrigerant
cycle. Entry of air will cause extremely high pressure inside the refrigerant
cycle, possibly resulting in breakage of pipes.
PEH-P400MYA
Piping Method Brazing
Height Difference
between Indoor and 40 m or less
Outdoor Units
Number of bends
15 or less
(right angles)
Total Piping Length 50 m or less
ø12.7 × 2
Refrigerant
Liquid Pipe
Pipe Size
ø25.4 × 2
Gas Pipe
(mm)
s Refer to the installation manual for details of the additional amount of
refrigerant for the outdoor unit.

7.2. Drain piping work

[Fig. 7.2.1] (P.3)
A Insulator
C Drain pan
> = 2 × F > =
E
70 mm
G Downward slope 20 mm/m or more H Drain trap
I The drain pipe should extend below this level.
J Open drain
PEH-P400MYA PEH-P500MYA
ø12.7
ø25.4 ø28.58
R1 (Male screw)
B Refrigerant pipe (gas pipe)
C Gas pipe
F Indoor unit
PEH-P500MYA
Brazing
40 m or less
15 or less
50 m or less
ø12.7 × 2
ø28.58 × 2
B Drain pipe R1
> =
D
70 mm
> =
F
35 mm