Installation manual
7
250B8W1B
Split system air conditioner
4PW25544-1A
Cautions for necessity of a trap
Since there is fear of the oil held inside the riser piping flowing back into
the compressor when stopped and causing liquid compression
phenomenon, or cases of deterioration of oil return, it will be necessary
to provide a trap at an appropriate place in the riser gas piping.
■
Trap installation spacing.
A
Outdoor unit
B
Indoor unit
C
Gas piping
D
Liquid piping
E
Oiltrap
H
Install trap at each difference in height of 10 m.
■
A trap is not necessary when the outdoor unit is installed in a
higher position than the indoor unit.
7.8.
Leak test and vacuum drying
■
Do not purge the air with refrigerants. Use a vacuum pump to
vacuum the installation. No additional refrigerant is provided for
air purging.
■
Pipes inside the units were checked for leaks by the
manufacturer. The refrigerant pipes fit on site are to be checked
for leaks by the installer.
■
Confirm that the valves are firmly closed before leak test or
vacuuming.
■
Make sure that valve A is completely open.
Set up for vacuuming and leak test:
Procedure for leak test
Leak test must satisfy EN378-2.
1
Evacuate the pipes and check vacuum
(1)
. (No pressure increase
for 1 minute.)
2
Break the vacuum with a minimum of 2 bar of nitrogen. (Never
pressurize more than 4.0 MPa.)
3
Conduct leak test by applying soap water, etc. to the connecting
part of the pipes.
4
Discharge nitrogen.
5
Evacuate and check vacuum again
.
6
If the vacuum gauge no longer rises, the stop valves can be
opened.
7.9.
Pipe insulation
After finishing the leak test and vacuum drying, the piping must be
insulated. Take into account the following points:
■
Make sure to insulate the connection piping and refrigerant
branch kits entirely.
■
Be sure to insulate liquid and gas piping.
■
Use heat resistant polyethylene foam which can withstand a
temperature of 70°C for liquid side piping and polyethylene foam
which can withstand a temperature of 120°C for gas side piping.
■
If you think the temperature and the relative humidity around the
cooling pipes might exceed 30°C and RH 80%, reinforce the
insulation of the cooling pipes (at least 20
mm thick).
Condensation might be formed on the surface of the insulation.
■
If there is a possibility that condensation on the stop valve might
drip down to the indoor side through gaps in the insulation and
piping because the outdoor unit is located higher than the indoor
unit this must be prevented by sealing up the connections. See
1
Pressure reducing valve
2
Nitrogen
3
Refrigerant tank
4
Stop valve
5
Weighing-machine
6
Vacuum pump
7
Valve A
8
Gas line stop valve
9
Liquid line stop valve
10
Stop valve service port
11
Charge hose
12
Indoor unit
13
Outdoor unit
14
... to indoor unit
(1) Use a 2-stage vacuum pump with a non return valve which can evacuate to
–100.7 kPa (5 Torr, –755 mm Hg).
Evacuate the system from the liquid and gas pipes by using a vacuum pump for
more than 2 hours and bring the system to –100.7 kPa. After keeping the system
under that condition for more than one hour, check if the vacuum gauge rises or
not. If it rises, the system may either contain moisture inside or have leaks.
Following should be executed if there is a possibility of
moisture remaining in the pipe (if piping work is carried out
during the raining season or over a long period of time,
rainwater may enter the pipe during work).
After evacuating the system for 2 hours, pressurize the
system to 0.05 MPa (vacuum break) with nitrogen gas and
evacuate the system again using the vacuum pump for
1 hour to –100.7 kPa (vacuum drying). If the system
cannot be evacuated to –100.7 kPa within 2 hours, repeat
the operation of vacuum break and vacuum drying. Then
after leaving the system in vacuum for 1 hour, confirm that
the vacuum gauge does not rise.
After air purging with a vacuum pump it may happen that
the refrigerant pressure does not rise, not even if the stop
valve is opened. Reason for this phenomenon is the closed
state of for instance the expansion valve in the outdoor unit
circuit, but this is not a problem for running the unit.
1
Liquid line stop valve
2
Gas line stop valve
3
Indoor -outdoor interconnection piping
4
Sealing up treatment
5
Heat insulator
Be sure to insulate local pipes, as touching them can
cause burns.
