Additional Refrigerant Charge - Mitsubishi Electric CITY MULTI PUMY-SM112VKM Installation Manual

3. Additional refrigerant charge
3.1. Additional refrigerant charge
Additional refrigerant charge
Refrigerant for the indoor units is not included in the outdoor unit when the unit is shipped from the factory.
Refrigerant of 1.4 kg equivalent to 27 m total extended piping length is already included when the outdoor unit is shipped. Thus, if the total extended piping length is 27
m or less, there is no need to charge with additional refrigerant for the piping. If the total extended piping length exceeds 27 m, charge each refrigerant piping system
with additional refrigerant at the installation site. In addition, in order to carry out service, enter the size and length of each liquid pipe and additional refrigerant charge
amounts in the spaces provided on the "Refrigerant amount" plate on the outdoor unit.
* When the unit is stopped, charge the unit with the additional refrigerant through the liquid stop valve after the pipe extensions and indoor units have been
vacuumized.
When the unit is operating, add refrigerant to the gas check valve using a safety charger. Do not add liquid refrigerant directly to the check valve.
Calculation of additional refrigerant charge
• Calculate the additional charge amount based on the designated amount for total capacity of connected indoor units and the extended piping. When the amount for
the extended piping is less than 0, calculate the additional charge amount without it.
• Calculate the additional refrigerant charge using the procedure shown below, and charge with the additional refrigerant.
• For amounts less than 0.1 kg, round up the calculated additional refrigerant charge.
(For example, if the calculated charge is 6.01 kg, round up the charge to 6.1 kg.)
• The amount of additional refrigerant which is calculated from the total capacity of indoor units and the combination of extended pipes must not be over 4.5 kg.
<Additional Charge>
Calculation of refrigerant charge
Additional Additional
refrigerant charge for refrigerant charge for
the piping = the indoor units
(kg)
Included refrigerant amount when shipped from the factory
Included refrigerant amount
3.0 kg
<Example>
Outdoor model : SM140
Indoor 1 : P100 (11.2 kW)
2 : P40 (4.5 kW)
The total length of each pipe size is as follows:
ø9.52 : A = 30 m
ø9.52 : a = 15 m
ø6.35 : b = 10 m
<Calculation example>

Additional refrigerant charge

1.8 + (30 + 15) × 0.051 + 10 × 0.019 - 1.4 = 2.9 kg (rounded up)
Liquid pipe size Liquid pipe size
Total length of Total length of
+ ø9.52 × 0.051 + ø6.35 × 0.019
1.8 kg (m) × 0.051 (kg/m) (m) × 0.019 (kg/m)
Additional charge amount for piping
* If this value is less than 0, the additional
charge amount for the piping shall be 0.
A : ø9.52 30 m
At the conditions
a : ø9.52 15 m
below:
b : ø6.35 10 m
Refrigerant
amount for outdoor
- unit
1.4 kg
en
5