128
Refrigerant pipe installation
Vacuuming
(1) After the airtight test, discharge nitrogen gas.
Connect a gauge manifold to the service ports at liquid, gas and balance sides, and connect a vacuum pump as shown
in the following figure.
Be sure to perform vacuuming at liquid, gas, and balance sides.
(2) Use a vacuum pump with a large displacement so that the vacuum will achieve below 0.750mmHg.
(3) Perform vacuuming for 2 or 3 hours, though time requirement differs due to pipe length. During this time, check that all
packed valves at liquid, gas, and balance sides are fully closed.
(4) If vacuuming does not reach 0.750mmHg or below even after vacuuming for 2 hours or more, perform vacuuming for a
futher hour. If vacuuming still does not reach 0.750mmHg after 3 hours, check for leakage.
(5) When vacuuming reaches 0.750mmHg or below after vacuuming, fully close valves. Close VL and VH on the gauge
manifold fully, stop the vacuum pump. After 1 hour check the vacuum gauge reading has not change. If there is a
change, there may be a leak. Check for leak.
(6) After the above procedure of vacuuming has completed, replace the vacuum pump with a refrigerant cylinder, and
advance to additional refrigerant charging work.
17
Connected to indoor unit
Low
pressure
gauge
High
pressure
gauge
Packed valve fully
closed (gas side)
Inverter outdoor unit
Main pipe
Gauge
manifold
Detailed drawing of packed valve
To gauge manifold
{
Gas-side
service port
Liquid-side
service port
Liquid-side
packed valve
Gas-side
packed valve
To main
unit
To main
unit
Piping at site
Piping at site
Piping at site
To main unit
Balance
service port
Balance
packed valve
Connected to other fixed-speed outdoor unit
Brazed
Service
port
Vacuum pump
Service port
Fully closed
Fully closed
Packed valve fully
closed (liquid side)
Packed valve fully
closed (balance)
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