DC Inverter U-match Series Duct Type Unit
17
(2). If the outdoor unit is installed higher than the
indoor unit (See Fig. 4.18)
1). Taping should be done from lower to the upper
part.
2). All pipes are bound and taped together and also
should be trapped to prevent water from
returning to the room.
3). Restraint all pipes to the wall with saddles.
Fig. 4.18
4.4 Vacuum and Gas Leakage Inspection
Do not purge the air with refrigerants but use a vacuum pump to vacuum the installation! There is no
extra refrigerant in the outdoor unit for air purging!
4.4.1 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).
(7). Slightly open the liquid valve and let some refrigerant go to the connection
pipe to balance the pressure inside and outside of the connection pipe, so that
