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6 Use a fitting if a specified refrigerant pipe has a different diameter from that
of a branching pipe.
7 Always observe the restrictions on the refrigerant piping (such as rated
length, height difference, and piping diameter) to prevent equipment failure
or a decline in heating/cooling performance.
8 Branching cannot be made after header branching (corresponding parts are
marked with
in the diagram below).
To the outdoor unit
To the outdoor unit
9 Either a lack or an excess of refrigerant causes the unit to make an
emergency stop. Charge the system with an appropriate amount of
refrigerant. When servicing, always check the notes concerning pipe
length and amount of additional refrigerant at both locations, the refrigerant
volume calculation table on the back of the service panel and the additional
refrigerant section on the labels for the combined number of indoor units
(Refer to item 9.2. for detailed information on refrigerant piping system).
0 Be sure to charge the system using liquid refrigerant.
a Never use refrigerant to perform an air purge. Always evacuate using a
vacuum pump.
b Always insulate the piping properly. Insufficient insulation will result in a decline
in heating/cooling performance, water drops from condensation and other such
problems (Refer to item 10.4 for thermal insulation of refrigerant piping).
c When connecting the refrigerant piping, make sure the valve of the outdoor
unit is completely closed (the factory setting) and do not operate it until the
refrigerant piping for the outdoor and indoor units has been connected, a
refrigerant leakage test has been performed and the evacuation process has
been completed.
d Braze only with non-oxide brazing material for piping. Failure to do so
may damage the compressor. Be sure to perform the non-oxidation
brazing with a nitrogen purge.
Do not use any commercially available anti-oxidizing agent since it may
cause pipe corrosion and degrading of the refrigerant oil.
Please contact Mitsubishi Electric for more details.
(Refer to item 10.2. for details of the piping connection and valve operation)
e Never perform outdoor unit piping connection work when it is raining.
Warning:
When installing and moving the unit, do not charge the system with any
other refrigerant other than the refrigerant specified on the unit.
- Mixing of a different refrigerant, air, etc. may cause the refrigerant cycle to
malfunction and may result in severe damage.
Caution:
•
Use a vacuum pump with a reverse flow check valve.
- If the vacuum pump does not have a reverse flow check valve, the vacuum
pump oil may flow back into the refrigerant cycle and cause deterioration of
the refrigerant oil.
•
Do not use the tools shown below used with conventional refrigerant.
(Gauge manifold, charge hose, gas leak detector, check valve, refrigerant
charge base, vacuum gauge, refrigerant recovery equipment)
- Mixing of conventional refrigerant and refrigerant oil may cause the
refrigerant oil to deteriorate.
10. Additional refrigerant charge
At the time of shipping, the outdoor unit is charged with refrigerant.
This charge does not include the amount needed for extended piping and
additional charging of each refrigerant line will be required on site. In order that
future servicing may be properly provided, always keep a record of the size and
length of each refrigerant line and the amount of additional charge by writing it in
the space provided on the outdoor unit.
10.1. Calculation of additional refrigerant
charge
•
Calculate the amount of additional charge based on the length of the piping
extension and the size of the refrigerant line.
•
Use the table to the right as a guide to calculating the amount of additional
charging and charge the system accordingly.
16
- Mixing of water will cause the refrigerant oil to deteriorate.
- R410A refrigerant does not contain any chlorine. Therefore, gas leak
detectors for conventional refrigerants will not react to it.
•
Manage the tools used for R410A more carefully than normal.
- If dust, dirt, or water gets in the refrigerant cycle, the refrigerant oil will deteriorate.
•
Never use existing refrigerant piping.
- The large amount of chlorine in conventional refrigerant and refrigerant 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.
•
Do not use a charging cylinder.
- Using a charging cylinder may cause the refrigerant to deteriorate.
•
Do not use special detergents for washing piping.
9.2. Refrigerant piping system
Connection example
CAP
[Fig. 9.2.1] (P.4)
A Outdoor unit
C Indoor unit
E Outdoor twinning kit
*1 ø12.7 for over 90 m
*2 ø12.7 for over 40 m
*3 The pipe sizes listed in columns A1 to A3 in this table correspond to the sizes
Precautions for outdoor unit combinations
Refer to [Fig. 9.2.2] for the positioning of twinning pipes.
[Fig. 9.2.2] (P.6)
<A> Make sure the pipes from the twinning pipe to the outdoor unit are sloped
downwards (towards the twinning pipes).
<B> When the piping on the outdoor unit side (from the twinning pipe) exceeds 2 m,
ensure a trap (gas pipe only) within 2 m. Make sure the height of the trap is
200 mm or more.
If there is no trap, oil can accumulate inside the pipe, causing a shortage of
oil and may damage the compressor.
<C> Slope of twinning pipes
Make sure the slope of the twinning pipes are at an angle within ±15° to the
ground.
If the slope exceeds the specified angle, the unit may be damaged.
<D> Pipe connection example
Downward slope
A
Indoor unit
C
Within 2 m
E
Slope of the twinning pipes are at an angle within ±15° to the ground
G
Pipes on site
H
Straight run of pipe that is 500 mm or more
J
ODø12.7 × IDø9.52 (included with outdoor unit)
6
ODø19.05 × IDø15.88 (included with outdoor unit)
8
ODø34.93 × IDø28.58 (included with outdoor unit)
c
( 6 , 8 , c : Refer to item 10.2.)
Caution:
•
Do not install traps other than the ones between outdoor units described on
a separate sheet to prevent oil backflow and compressor start-up failure.
•
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.
•
If the calculation results in a fraction of less than 0.1 kg, round up to the next
0.1 kg. For example, if the result of the calculation was 12.38 kg, round the
result up to 12.4 kg.
<Additional Charge>
Additional
refrigerant charge
Outdoor model
Gas pipe
Model number
Joint
The 1st branch of P700, P750, P800
4-Branching header (Downstream unit model total 200)
8-Branching header (Downstream unit model total 400)
10-Branching header (Downstream unit model total 650)
Outdoor twinning kit
B First branch
D Cap
for the models listed in the unit 1, 2, and 3 columns. When the order of the
models for unit 1, 2, and 3 change, make sure to use the appropriate pipe size.
Upward slope
B
Trap (gas pipe only)
D
Twinning pipe
F
Twinning kit
I
Liquid pipe size
Liquid pipe size
Total length of
Total length of
+
=
ø19.05 × 0.29
ø15.88 × 0.2
(kg)
(m) × 0.29 (kg/m)
(m) × 0.2 (kg/m)
Liquid pipe size
Liquid pipe size
Total length of
Total length of
+
+
ø9.52 × 0.06
ø6.35 × 0.024
(m) × 0.06 (kg/m)
(m) × 0.024 (kg/m)
Liquid pipe
Total capacity of indoor units
Downstream unit model total
The 1st branch of P450 ~ P650
Liquid pipe size
Total length of
+
ø12.7 × 0.12
(m) × 0.12 (kg/m)
+ α
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