U-Match Series DC Inverter Service Manual
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3.1.5 Checking the Pipe Connections for Gas Leaking
For both indoor and outdoor unit side, check the joints for gas leaking by the use of a gas leakage
detector without fail when the pipes are connected.
3.1.6 Heat Insulation on the Pipe Joints (Indoor Side Only)
Stick coupler heat insulation (large and small) to the place where connecting pipes.
3.1.7.1 Vacuum
(1) Remove the caps of the liquid valve, gas valve and also the service port.
(2) Connect the hose at the low pressure side of the manifold valve assembly to the service port of
the unit’s gas valve, and meanwhile the gas and liquid valves should be kept closed in case of
refrigerant leak.
(3) Connect the hose used for evacuation to the vacuum pump.
(4) Open the switch at the lower pressure side of the manifold valve assembly and start the vacuum
pump. Meanwhile, the switch at the high pressure side of the manifold valve assembly should be
kept closed, otherwise evacuation would fail.
(5) The evacuation duration depends on the unit’s capacity, generally, 20 minutes for the 18k units,
30 minutes for the 24k/30k/36k units, 45 minutes for the 42k/48k units. And verify if the pressure
gauge at the low pressure side of the manifold valve assembly reads -1.0MPa (145psig), if not, it
indicates there is leak somewhere. Then, close the switch fully and then stop the vacuum pump.
(6) Wait for some time to see if the system pressure can remain unchanged, 3 minutes for the
18k/24k units, 10 minutes for the 30k/36k/42k/48k units. During this time, the reading of the
pressure gauge at the low pressure side can not be larger than 0.005MPa (0.72psig).
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