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Sealing of the Knock-off Hole
With the built-in valve model, pipe connection during the installation process, where the connection pipe is passing
through the knock-out holes, seal the unused knock-out holes of the outdoor unit with insulated cotton to prevent small
animals from entering. See the following figures.
Connection Pipe Vacuum Pumping and Leak Detection
Vacuum Pumping
Make sure the outlet of vacuum pump is away from fire source and is well-ventilated.
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.
Model
Time(min)
VRUO-2436HP-U2B(54)
30
VRUO-4860HP-U2B(54)
30
And verify if the pressure gauge at the low pressure side of the manifold valve assembly reads -0.1Mp (-75cmHg), if not, it
indicates there is leak somewhere. Then, close the switch fully and then stop the vacuum pump.
6. Wait for 10 min to see if the system pressure can remain unchanged. During this time, the reading of the pressure
gauge at the low pressure side cannot 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
: 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.