Refrigerant Piping Work
Refrigerant piping is important in particular. Refrigeration cycle of the split air
conditioner is realized by the perfect piping work.
Piping Length and Elevation
If the piping is too long, both the capacity and reliability of the unit will drop. As the number of bends
increase, resistance to flow of refrigerant increases, thus lowering the cooling capacity and as a result
overloading the compressor which may cause the compressor to become defective. Always choose the
shortest path and follow the recommendation as tabulated below.
Indoor
MCK015B/BR
MCK020A/AR
MCK020B/BR
MCK025A/AR
MCK025B/BR
MCK030A/AR
MCK030B/BR
MCK040A/AR MCK050A/AR
Model
Outdoor
MLC/ M4LC
015B/BR
MLC/M4LC
020B/BR
MLC/ M4LC
025B/BR
MLC030B/BR
MLC/ M4LC
030C/CR
MLC035C/CR
MLC/ M4LC
040C/CR
MLC/ M4LC
050C/CR
Max. length (m)
10 15 15 15 35 35 35 35
Max. elevation (m)
5 8 8 8 15 15 15 15
Max. no. of bends
10 10 10 10 10 10 10 10
Liquid pipe size
1/4" 1/4" 3/8’’ 3/8’’ 3/8’’ 3/8" 3/8" 3/8’’
Gas pipe size
1/2” 5/8” 5/8’’ 5/8’’ 5/8’’ 3/4'’ 3/4'’ 3/4'’
Indoor MCK010C/CR MCK015C/CR MCK020C/CR
Model
Outdoor MLC00B/BR MLC015B/BR MLC020B/BR
Max. length (m) 12 12 15
Max. elevation (m) 5 5 8
Max. no. of bends 10 10 10
Liquid pipe size 1/4" 1/4" 1/4"
Gas pipe size 3/8" 3/8" 5/8"
Remark: The refrigerant pre-charged in the outdoor unit is for piping length up to 7.62m
Piping Connection
Do not use contaminated or damaged copper tubing. If piping for evaporator or condenser are exposed or
had been opened for 15 seconds or more, vacuum and purge with field supplied refrigerant. Generally, do
not remove plastic, rubber plugs and brass nuts from valves, fittings, tubing and coils until it is ready to do
the connection for suction and liquid line.
If any brazing work is required, ensure that nitrogen gas is passed through coil and joints while brazing work
is being carried out. This will eliminate soot formation on the inside wall of copper tubing.
Cut the pipe stage by stage, advance the blade of pipe cutter slowly. Extra force and deep cut will cause
more distortion of pipe and therefore produce extra burr.
Remove burrs from cut edges of pipes with a remover. This will avoid unevenness on the flare face which
will cause gas leak.
Align the center of the piping and sufficiently tighten the flare nut with fingers. Finally, tighten the flare nut
with torque wrench until the wrench clicks.
Be sure to execute heat insulation (polyurethane form with thickness more than 15 mm).
Except the outdoor unit which is pre-charged with refrigerant, the indoor unit and the refrigerant connection
pipes must be purged because the air that contain moisture remaining in the refrigerant cycle may cause
malfunction to the compressor.
Additional Charge
The refrigerant is pre-charged in the outdoor unit, but additional charge of refrigerant after vacuuming is
necessary. Follow the recommendation as tabulated below.
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