Additional Refrigerant Charge; Calculation Of Additional Refrigerant Charge - Mitsubishi Electric PUHY-HP-THMU-A Installation Manual

<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.
G
<D> Pipe connection example
H
A
Downward slope
F
Twinning pipe
I
Twinning Kit

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 below as a guide for calculating the amount of additional charg-
ing and then charge the system accordingly.
• If the calculation results in a fraction of less than 0.1 kg [4 oz], round up to the
next 0.1 kg [4 oz]. For example, if the result of the calculation was 11.38 kg
[402 oz], round the result up to 11.4 kg [404 oz].
<Additional Charge>
Additional Liquid pipe size
refrigerant charge Total length of
ø19.05 mm [3/4"]
=
(m) × 0.29 (kg/m)
(kg) [oz]
(ft) × 3.1 (oz/ft)
Liquid pipe size
Total length of
+
ø9.52 mm [3/8"]
(m) × 0.06 (kg/m)
(ft) × 0.65 (oz/ft)
F
I
H
J
B C
Upward slope 1st branch
G
Slope of the twinning pipes are at an angle within ±15˚ to the ground
J
Straight run of pipe that is 500 mm [19-11/16 in] or more
Liquid pipe size Liquid pipe size
Total length of Total length of
ø15.88 mm [5/8"] ø12.7 mm [1/2"]
+ +
(m) × 0.2 (kg/m) (m) × 0.12 (kg/m)
(ft) × 2.15 (oz/ft) (ft) × 1.29 (oz/ft)
Liquid pipe size
Total length of
+ + α
ø6.35 mm [1/4"]
(m) × 0.024 (kg/m)
(ft) × 0.26 (oz/ft)
D E
Trap (gas pipe only) Within 2 m [6 ft]
H
Pipes on site
<Example>
Indoor
1: 48 A: ø12.7 mm [1/2"] 40 m [131 ft] a: ø9.52 mm [3/8"] 10 m [32 ft]
2: 36 B: ø9.52 mm [3/8"] 10 m [32 ft]
3: 15 C: ø9.52 mm [3/8"] 15 m [49 ft]
4: 12 D: ø9.52 mm [3/8"] 10 m [32 ft]
5: 24
The total length of each liquid line is as follows:
ø12.7 mm [1/2"]: A = 40 m [131 ft] = 40 m [131 ft]
ø9.52 mm [3/8"]: B + C + D + a + b + e
= 10 m [32 ft] + 15 m [49 ft] + 10 m [32 ft] + 10 m [32 ft] +
5 m [16 ft] + 10 m [32 ft] = 60 m [193 ft]
ø6.35 mm [1/4"]: c + d = 10 m [32 ft] + 10 m [32 ft] = 20 m [64 ft]
Therefore,
<Calculation example>
Additional refrigerant charge
= 40 m [131 ft] × 0.12 kg/m [1.29 oz/ft] + 60 m [193 ft] × 0.06 kg/m [0.65 oz/ft]
+ 20 m [64 ft] × 0.024 kg/m [0.26 oz/ft] + 3.5 kg [124 oz] = 12.4 kg [435 oz]
Value of α
Total capacity of connecting indoor units
Models ~ 27
Models 28 ~ 54
Models 55 ~ 126
Models 127 ~ 144
Models 145 ~ 180
Models 181 ~ 234
Models 235 ~
At the
b: ø9.52 mm [3/8"] 5 m [16 ft]
conditions
c: ø6.35 mm [1/4"] 10 m [32 ft]
below:
d: ø6.35 mm [1/4"] 10 m [32 ft]
e: ø9.52 mm [3/8"] 10 m [32 ft]
α
2.0 kg [71 oz]
2.5 kg [89 oz]
3.0 kg [106 oz]
3.5 kg [124 oz]
4.5 kg [160 oz]
5.0 kg [177 oz]
6.0 kg [212 oz]
9