Refrigerant Piping Installation; Caution; Refrigerant Piping System; Additional Refrigerant Charge - Mitsubishi Electric CITY MULTI PQHY-P400YSGM-A Manual De Instalación

8. Refrigerant piping installation

City Multi WR2 Series is constituted by an end branching system in which the
refrigerant piping from heat source unit is branched at BC controller and connected
to each indoor unit.
The connection method adapted is brazing connection for high pressure pipe and
low pressure pipe between heat source unit and BC controller, and flare connec-
tion between BC controller and indoor unit. Brazing connection is employed for
joint pipe set and branch pipe set.
Warning:
Always use extreme care to prevent the refrigerant gas from leaking while
using fire or flame. If the refrigerant gas comes in contact with a flame from
any source, such as a gas stove, it breaks down and generates a poisonous
gas which can cause gas poisoning. Never weld in an unventilated room.
Always conduct an inspection for gas leakage after installation of the refrig-
erant piping has been completed.

8.1. Caution

This unit uses refrigerant R410A. Follow the local regulations on materials and
pipe thickness when selecting pipes.
1 Use the following materials for refrigeration piping.
• Material: Use refrigerant piping made of phosphorus deoxidized copper.
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.
2 Commercially available piping often contains dust and other materials. Always
blow it clean with a dry inert gas.
3 Use care to prevent dust, water or other contaminants from entering the piping
during installation.
4 Reduce the number of bending portions as much as possible, and make bend-
ing radius as big as possible.
5 Always observe the restrictions on the refrigerant piping (such as rated length,
the difference between high/low pressures, and piping diameter). Failure to do
so can result in equipment failure or a decline in heating/cooling performance.
6 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. At such a
time, always properly charge the unit. 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.
7 Use liquid refrigerant to fill the system.
8 Never use refrigerant to perform an air purge. Always evacuate using a vacuum
pump.
9 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.
0 When connecting the refrigerant piping, make sure the ball valve of the heat
source unit is completely closed (the factory setting) and do not operate it until
the refrigerant piping for the heat source and indoor units has been connected,
a refrigerant leakage test has been performed and the evacuation process has
been completed.

9. Additional refrigerant charge

At the time of shipping, the heat source unit is charged with the refrigerant. As this
charge does not include the amount needed for extended piping, additional charg-
ing for 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 pro-
vided on the heat source unit.
9.1. 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 below as a guide to calculating the amount of additional
charging and charge the system accordingly.
• 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 19.58 kg, round the
result up to 19.6 kg.
12
A Residues in commercially available antioxidants may have adverse effects on
the equipment. Braze only with non-oxide brazing material. The use of other
brazing material may result in compressor damage.
(Refer to item 9.2. for detailed information on pipe connections and valve op-
erations.)
B Never perform heat source unit piping connection work when it is raining.
Warning
When installing and moving the unit, do not charge it with 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 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 and other trouble.
• 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 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.
• Manage the tools more carefully than normal.
- If dust, dirt, or water gets in the refrigerant cycle, the refrigerator oil will dete-
riorate.
• 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.
• Do not use a charging cylinder.
- Using a charging cylinder may cause the refrigerant to deteriorate.
• Do not use special detergents for washing piping.

8.2. Refrigerant piping system

Connection Example
[Fig. 8.2.1] (P.4)
Å Heat source model
Ç Gas pipe
‰ Model number
Ì Branch kit model
¬ 4-Branching header (Downstream unit model total
Ô 8-Branching header(Downstream unit model total
10-Branching header (Downstream unit model total
Ò High press pipe
ˆ Bypass pipe
A Heat source unit
C Indoor unit
<Additional Charge>
Additional Liquid pipe size Liquid
refrigerant Total length of Total length of
= × 0.20 + ø12.7 × 0.12
charge ø15.88
(m) × 0.20 (kg/m) (m) × 0.12 (kg/m)
(kg)
Liquid pipe size
Total length of
+ α1 + α2
+ × 0.024
ø6.35
(m) × 0.024 (kg/m)
Outdoor: 500
Indoor No. 1: 100 A: ø15.88 40 m
No. 2: 100 B: ø15.88 10 m
No. 3: 40 C: ø12.7 10 m
No. 4: 32 D: ø9.52 10 m
No. 5: 250 E: ø19.05
ı
Liquid pipe
Î Total capacity of indoor units
Ï Downstream unit model total
Ó The 1st branch of P450 ~ P650
< =
200)
< =
400)
< =
650)
˜ Low press pipe
B First branch
D Cap
pipe size Liquid pipe size
Total length of
+
ø9.52 × 0.06
(m) × 0.06 (kg/m)
a: ø9.52 10 m
b: ø9.52 5 m
At the
c: ø6.35 10 m
conditions
d: ø6.35 10 m
below:
5 m e: ø9.52 10 m