Mitsubishi MXZ-8B140VA Technical & Service Manual page 62

<Table 1>
Total piping length
(b1+ b2 + a1+ a2 + a3 + a4 + a5 + a6 + a7 + a8)
Additional refrigerant charging amount
* Reference (for service)
The amount of refilling refrigerant charge
If connecting an indoor unit with [9.52 liquid pipes (model number 71 or more for M-and S-series and model number 60 or more
for P-series), the additional refrigerant charging amount in Table 1 must be corrected (add the following R value from the value
given in Table 1).
Additional refrigerant charging correction amount
R=0.01 [kg/m] o [9.52 branch pipe (liquid pipe) total length [m]
Example) b1 = 20m, b2 = 25m
Indoor unit A [9.52 liquid pipe
Indoor unit B [6.35 liquid pipe
Indoor unit C [6.35 liquid pipe
Indoor unit D [9.52 liquid pipe
Total piping length : b1 + b2 + a1 + a2 + a6 + a7 = 95m
➝ According to Table 1, the additional refrigerant charging amount is 3.2kg.
Because indoor units with [9.52 liquid pipes are connected (indoor units A and D in this example), the additional refrigerant
charging amount must be corrected.
Additional refrigerant charging correction amount
R = 0.01 [kg/m] o [9.52 branch pipe (liquid pipe) total length (a1 + a7)
= 0.01 o (12 + 13m)
= 0.25kg
Therefore, the additional refrigerant charging amount is 3.2kg + 0.25kg = 3.45kg.
* Reference
The refilling amount of refrigerant at servicing
Example) 3.45 + 8.5 = 11.95kg
The amount of refrigerant of initial charge (8.5kg) is added.
* Although two ø6.35 liquid pipes are used between the branch box and the Y-shape connection pipe when connecting the P100 indoor unit,
calculate the additional refrigerant charging amount assuming only one ø9.52 liquid pipe is used.
12-2. REFRIGERANT COLLECTING (PUMP DOWN)
Perform the following procedures to collect the refrigerant when moving the indoor unit or the outdoor unit.
Turn off the circuit breaker.
1
Connect the low pressure side of the gauge manifold to the service port of the gas side stop valve.
2
Close the liquid stop value.
3
Supply power (circuit breaker).
4
* S tart-up of the indoor-outdoor communication takes about 3 minutes after the power (circuit breaker) is turned on. Start the pump-down opera-
tion 3 to 4 minutes after the power (circuit breaker) is turned ON.
P erform the test run for cooling operation (SW4-1: ON and SW4-2: OFF). The compressor (outdoor unit) and ventilators (indoor and outdoor
5
units) start operating and test run for cooling operation begins.
* O nly set the SW4-1 and SW4-2 to ON if the unit is stopped. However, even if the unit is stopped and the SW4-1 and SW4-2 are set to ON less
than 3 minutes after the compressor stops, the refrigerant collecting operation cannot be performed. Wait until compressor has been stopped
for 3 minutes and then set the SW4-1 and SW4-2 to ON again.
Fully close the gas stop valve when the pressure reading on the gauge drops 0.05 - 0.00 MPa (approximately 0.5 - 0.0 kgf/cm²)
6
Stop the air conditioner operation. (SW4-1: OFF and SW4-2: OFF)
7
Turn off the power supply (circuit breaker).
8
* I f too much refrigerant has been added to the air conditioner system, the pressure may not drop to 0.5 kgf/cm². If this occurs, use a refrigerant
collecting device to collect all of the refrigerant in the system, and then recharge the system with the correct amount of refrigerant after the indoor
and outdoor units have been relocated.
Warning:
When pumping down the refrigerant, stop the compressor before disconnecting the refrigerant pipes. The compressor may burst if air
etc. get into it.
OCH480D
40m or less 41 – 50m
0kg (no need) 0.6kg
8.5kg 9.1kg
(8.5 + 0) (8.5 + 0.6)
a1 = 12m
a2 = 11m
a6 = 14m
a7 = 13m
62
51 – 70m 71 – 90m
1.4kg 2.2kg
9.9kg 10.7kg
(8.5 + 1.4) (8.5 + 2.2)
91 – 115m
3.2kg
11.7kg
(8.5 + 3.2)