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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 serv-
icing, 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 infor-
mation 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 de-
cline 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 re-
frigerant 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 braz-
ing 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 mal-
function 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 refrigerator oil.
•
Do not use the tools shown below used with conventional refrigerant.
(Gauge manifold, charge hose, gas leak detector, check valve, refriger-
ant charge base, vacuum gauge, refrigerant recovery equipment)
- Mixing of conventional refrigerant and refrigerator oil may cause the refrig-
erator oil to deteriorate.
- Mixing of water will cause the refrigerator oil to deteriorate.
- R410A refrigerant does not contain any chlorine. Therefore, gas leak detec-
tors for conventional refrigerants will not react to it.
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 serv-
icing 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.
•
Manage the tools used for R410A more carefully than normal.
- If dust, dirt, or water gets in the refrigerant cycle, the refrigerator oil will dete-
riorate.
•
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
CAP
Connection example
[Fig. 9.2.1] (P.3, 4)
Å Outdoor model
Ç Gas pipe
‰ Model number
Ì Joint
¬ The 1st branch of P700, P750, P800
Ô 4-Branching header (Downstream unit model total
8-Branching header (Downstream unit model total
Ò 10-Branching header (Downstream unit model total
˜ Outdoor twinning kit
A Outdoor unit
C Indoor unit
E Outdoor twinning kit
*1
*2
Precautions for outdoor unit combinations
Refer to [Fig. 9.2.2] for the positioning of twinning pipes.
[Fig. 9.2.2] (P.5)
<A> Make sure the pipes from the twinning pipe to the outdoor unit are sloped
<B> When the piping on the outdoor unit side (from the twinning pipe) exceeds 2 m,
<C> Slope of twinning pipes
<D> Pipe connection example
A Downward slope
C Indoor unit
E Within 2 m
G Slope of the twinning pipes are at an angle within ±15° to the ground
H Pipes on site
J Straight run of pipe that is 500 mm or more
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 fail-
ure.
•
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 11.38 kg, round the
result up to 11.4 kg.
<Additional Charge>
Additional
refrigerant charge
ı Liquid pipe
Î Total capacity of indoor units
Ï Downstream unit model total
Ó The 1st branch of P450 ~ P650
B First branch
D Cap
The pipe sizes listed in columns A1 to A3 in this table correspond to the sizes 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.
ø25.4 for R22
downwards (towards the twinning pipes).
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.
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.
B Upward slope
D Trap (gas pipe only)
F Twinning pipe
I Twinning kit
Liquid pipe size
Liquid pipe size
Total length of
Total length of
=
+
ø19.05 × 0.29
ø15.88 × 0.2
(m) × 0.29 (kg/m)
(m) × 0.2 (kg/m)
(kg)
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)
200)
=
400)
=
650)
=
Liquid pipe size
Total length of
+
ø12.7 × 0.12
(m) × 0.12 (kg/m)
+ α
15
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