DC Inverter Duct Type Unit
16
4.4 Vacuum and Gas Leakage Inspection
CAUTION!
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 36K units,
And verify if the pressure gauge at the low pressure side
of the manifold valve assembly reads -1.0Mp (-75cmHg), 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,
5 minutes for the 18K~24K units, 10 minutes for the
unit 36k
During this time, the reading of the pressure gauge at the low pressure side can not
be larger than 0.005Mp (0.38cmHg).
(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 air will not come into the
connection pipe when removing the hose. Note that the gas and liquid valve can be opened
fully only after the manifold valve assembly is removed.
(8). Place back the caps of the liquid valve, gas valve and also the service port.
Hose with the valve pin
gauge manifold
pipe
pipe
VAC valve
Vacuum pump
Service port
Low pressure gauge
High pressure gauge
Gauge manifold kit
Fig.22
Note: For the large-sized unit, it has the service port for both the gas valve and the liquid valve.
