EDM SYSHP MINI SPLIT 06 16

Table Of Contents
75
3.10.2 Procedure
Notes for installers
During vacuum drying, a vacuum pump is used to lower the pressure in the piping to the extent that any moisture present
evaporates. At 5mmHg (755mmHg below typical atmospheric pressure) the boiling point of water is 0°C. Therefore a vacuum
pump capable of maintaining a pressure of -755mmHg or lower should be used. Using a vacuum pump with a discharge in
excess of 4L/s and a precision level of 0.02mmHg is recommended.
Cauon
Before performing vacuum drying, make sure that the outdoor unit stop valves are rmly closed.
Once the vacuum drying is complete and the vacuum pump is stopped, the low pressure in the piping could suck vacuum
pump lubricant into the air condioning system. The same could happen if the vacuum pump stops unexpectedly during
the vacuum drying procedure. Mixing of pump lubricant with compressor oil could cause compressor malfuncon and a
one-way valve should therefore be used to prevent vacuum pump lubricant seeping into the piping system.
Procedure
The vacuum drying procedure is as follows:
Step 1
Connect the blue (low pressure side) hose of a pressure gauge to the outdoor unit gas pipe stop valve, the red (high pressure
side) hose to the outdoor unit liquid pipe stop valve and the yellow hose to the vacuum pump.
Step 2
Start the vacuum pump and then open the pressure gauge valves to start vacuum the system.
Aer 30 minutes, close the pressure gauge valves.
Aer a further 5 to 10 minutes check the pressure gauge. If the gauge has returned to zero, check for leakages in the
refrigerant piping.
Step 3
Re-open the pressure gauge valves and connue vacuum drying for at least 2 hours and unl a pressure dierence of
756mmHg or more has been achieved. Once the pressure dierence of at least 756mmHg has been achieved, connue
vacuum drying for 2 hours.
Step 4
Close the pressure gauge valves and then stop the vacuum pump.
Aer 1 hour, check the pressure gauge. If the pressure in the piping has not increased, the procedure is nished. If the
pressure has increased, check for leakages.
Aer vacuum drying, keep the blue and red hoses connected to the pressure gauge and to the outdoor unit
stop valves, in preparaon for refrigerant charging (see Part 3, 3.11 “Charging Refrigerant”).
Figure 3-3.12: Pressure gauge