SiEN34-705
Installation
General Information
43
Vacuum Drying
Procedure
There are two vacuum drying methods and the appropriate one should always be chosen to
conform with individual local conditions.
[Normal vacuum drying]........The standard method
[Operational steps]
1. Vacuum drying (1st time): Connect a manifold gauge to the service port of the liquid or gas
pipe and operate the vacuum pump for at least 2 hours.
(The degree of vacuum produced should be in excess of -755 mmHg)
If after 2 hours the vacuum produced has not exceeded 5 mmHg then either there is
moisture in the pipe or there is a leak. Operate the vacuum pump for a further hour.
If, even after 3 hours, the vacuum has not reached -755 mmHg then check the system for a
leak.
2. Carry out maintained vacuum test.
Produce a vacuum in excess of -755 mmHg and do not release it for an hour or more. Check
the vacuum gauge to make sure that it has not risen. (If the gauge does rise then there is still
moisture in the pipe or there is a leak somewhere.)
3. Additional charge of refrigerant.
Connect the charging cylinder to the liquid pipe service port and charge with the required
amount of refrigerant.
4. Open stop valve to the full.
Open the stop valves on the liquid and the gas pipes to the full.
Note:
Vacuums should be produced in both the liquid and the gas pipes.
(Because there are a large number of functional components in the indoor unit which cut off the
vacuum mid–way through)
[Standard vacuum drying time chart]
Time required: approx. 3 hours.
Additional refrigerant
charge
(Atmospheric
pressure)
Failing
pressure
(vacuum)
Rising pressure
Vacuum
drying
Maintained
vacuum test
(2 hours) (1 hours)
