Additional Refrigerant Charge; Calculation Of Additional Refrigerant Charge; Precautions Concerning Piping Connection And Valve Operation - Mitsubishi Electric CITY MULTI PUHY-P-YREM-A Série Manuel D'installation

8. Additional Refrigerant Charge

At the time of shipping, the outdoor 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. Note that the method used for
calculating the additional refrigerant charge for a Replace Multi is different to that
used for the Y Series. 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.
8.1. 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.
• 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 12.62 kg, round the
result up to 12.7 kg.
<Additional Charge>
Additional Liquid pipe size
refrigerant charge Total length of
=
ø12.7 × 0.12
(m) × 0.12 (kg/m)
(kg)
<Example>
Indoor 1: 40 A: ø12.7 40 m
2: 100 B: ø12.7 10 m
3: 40 C: ø12.7 15 m
4: 32 D: ø12.7 10 m
5: 63
The total length of each liquid line is as follows:
ø12.7: A + B + C + D = 40 + 10 + 15 + 10 = 75 m
ø9.52: b + e = 5 + 10 = 15 m
ø6.35: a + c + d = 10 + 10 + 10 = 30 m
Therefore,
<Calculation example>
Additional refrigerant charge
= 75 × 0.12 + 15 × 0.06 + 30 × 0.024 – 2 = 8.7 kg
Value of α
α
2.0 kg
• If it is calculated that the additional refrigerant amount is 0.5kg or less, the
additional refrigerant amount is to be 0.5 kg.
8.2. Precautions concerning piping connec-
tion and valve operation
(1) Before mineral oil recovery
[Fig. 8.2.1] (P.3)
<A> [Ball valve (gas side)] (This figure shows the valve in the close state.)
<B> [Ball valve (liquid side)] (This figure shows the valve in the close state.)
A To oil trap kit
C Hollow Packing (Accessory)
E Service port
G Cap (Accessory)
I ø25.4 (PUHY-P200)
K Close-packed packing (Accessory) L Connecting pipe 3 (Accessory)
M Connecting pipe 4 (Accessory)
O ø25.4
• Conduct piping connection and valve operation accurately.
• The liquid-side connection pipe 3 is supplied with the outdoor unit.
1 Braze the ball valve on the liquid side.
2 Fit the cap and flare nut to isolate the refrigerant circuit.
• The gas-side connecting pipes 1,2,4 are supplied with the outdoor unit.
Connecting to the indoor unit side
1 For brazing to the connecting pipe with flange, remove the connecting pipe
with flange from the ball valve, and braze it.
2 If the pipe diameter of the existing onsite piping is ø25.4mm, make a brazed
connection using connecting pipe 2.
3 At the mounting of the hollow packing, wipe off dust attached on the flange
sheet surface and the packing.
Coat refrigerating machine oil (Ester oil, ether oil or alkyl benzene [small
amount] onto both surfaces of the packing.)
10
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)
a: ø6.35 10 m
At the
b: ø9.52 5 m
conditions
c: ø6.35 10 m
below:
d: ø6.35 10 m
e: ø9.52 10 m
B To indoor unit
D Connecting pipe 1 (Accessory)
F Flare nut (Accessory)
H ø12.7
J ø28.58 (PUHY-P250)
N Connecting pipe 2 (Accessory)
P Bolt M10 (Accessory)
Connecting to the oil trap kit side
1 Braze the ball valve on the gas side.
2 Insert the packing, consisting of rubber bushing with membrane, and fit the
connecting pipe with flange to isolate the refrigerant circuit.
• When the valve is open, it obstructs the mineral oil recovery operation so this
valve must be in the closed position.
• Determine the amount of additional refrigerant charge by using the formula,
and charge refrigerant additionally through the service port after completing
piping connection work.
• Refer to "(2) After mineral oil recovery" for the required tightening torque.
(2) After mineral oil recovery
• Conduct piping connection and valve operation accurately.
• The gas side connecting pipe is assembled in factory before shipment.
1 For brazing to the connecting pipe with flange, remove the connecting pipe
with flange from the ball valve, and braze it outside of the unit.
2 During the time when removing the connecting pipe with flange, remove
the seal attached on the rear side of this sheet and paste it onto the flange
surface of the ball valve to prevent the entry of dust into the valve.
3 The refrigerant circuit is closed with a round, close-packed packing upon
– α
shipment to prevent gas leak between flanges. As no operation can be
done under this state, be sure to replace the packing with the hollow pack-
ing attached at the piping connection.
4 At the mounting of the hollow packing, wipe off dust attached on the flange
sheet surface and the packing. Coat refrigerating machine oil (Ester oil,
ether oil or alkylbenzene [small amount]) onto both surfaces of the pack-
ing.
[Fig. 8.2.2] (P.3)
• After evacuation and refrigerant charge, ensure that the handle is fully open. If
operating with the valve closed, abnormal pressure will be imparted to the
high- or low-pressure side of the refrigerant circuit, giving damage to the com-
pressor, four-way valve, etc.
• Determine the amount of additional refrigerant charge by using the formula,
and charge refrigerant additionally through the service port after completing
piping connection work.
• After completing work, tighten the service port and cap securely not to gener-
ate gas leak.
[Fig. 8.2.3] (P.3)
<A> [Ball valve (gas side)] (This figure shows the valve in the fully open state.)
<B> [Ball valve (liquid side)]
A Valve stem
[Fully closed at the factory, when connecting the piping, when evacuating, and
when charging additional refrigerant. Open fully after the operations above are
completed.]
B Stopper pin [Prevents the valve stem from turning 90° or more.]
C Packing (Accessory)
[Manufacturer: Nichiasu corporation]
[Type: T/#1991-NF]
D Connecting pipe (Accessory)
[Use packing and securely install this pipe to the valve flange so that gas leakage
will not occur. (Tightening torque: 25 N·m) Coat both surfaces of the packing with
refrigerating machine oil. (Ester oil, ether oil or alkylbenzene [small amount])]
E Open (Operate slowly)
F Cap, copper packing
[Remove the cap and operate the valve stem. Always reinstall the cap after op-
eration is completed. (Valve stem cap tightening torque: 25 N·m or more)]
G Service port
[Use this port to evacuate the refrigerant piping and add an additional charge at
the site.
Open and close the port using a double-ended wrench.
Always reinstall the cap after operation is completed. (Service port cap tightening
torque: 14 N·m or more)]
H Flare nut
[Tightening torque: 55 N·m
Loosen and tighten this nut using a double-ended wrench.
Coat the flare contact surface with refrigerating machine oil (Ester oil, ether oil or
alkylbenzene [small amount])]
I ø12.7
J ø25.4 (PUHY-P200)
ø28.58 (PUHY-P250)
K Field piping
[Braze to the connecting pipe. (When brazing, use unoxidized brazing.)]
L Close-packed packing
M Hollow packing