Midea MGA-D30W/SN1, Manual

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MCAC-2008-11 Air-cooled Modular Chiller
54
In this case, leakage test must be done by using nitrogen (15
～
20 kgf/cm
2
) or refrigerant. If necessary,
welding should be done after all gas of the system is discharged out.
1) Connect the vacuum pump pipeline to the refrigerant charging hole.
2) Vacuum refrigerant pipeline more than 15 minutes and confirm it achieve -1.0×105Pa (-76cmHg).
3) After having achieved the designated vacuity, add refrigerant to the system from the cylinder,
corresponding volume of the refrigerant can be got from the nameplate and parameters table. It should be
noticed that charging just be allowed from the liquid pipeline side.
4) The volume charged into the system will vary from different surrounding Temperature, if the designated
volume can’t be achieved, unit can be started for recharging while the water system is running. Wire the
low-pressure switch to short circuit if necessary.
Notice:
rewiring the connection after charging.
2. Additional refrigerant charge
Connect refrigerant cylinder to the refrigerant charging hole and mount a pressure detector on the gas side
pipeline.
1) Recycle the chilled-water, then start unit, take low-pressure control switch to short circuit if necessary.
2) Charge the refrigerant into the system slowly, and check the discharge and suction pressure.
Warning: it is absolutely forbidden to charge the oxygen, acetylene or other gas which is poisonous or
flammable into the system for leak hunting or leakage test, just nitrogen or refrigerant is allowed.
Remove compressor
If it is necessary to remove the compressor, please operate with the sequence below:
1) Switch off the power
2) Remove the electric wire
3) Remove the suction and discharge pipeline
4) Loosen the fixing bolts.
5) Remove the compressor.
Auxiliary electric heater
When the outdoor Temperature (is) below 0 , the condenser outside will frost, which will cause the heat
℃
transfer efficiency come down, for the reason above, when using unit in the areas where the lowest Temp is
between -10
℃ ～
0 in the winter, it is recommended to select the auxiliary electric heat
℃
er to supply the
additional heat. Select the heater with the reference of “Specification Table”, if the Temp below -10 , the ℃
higher power-input can be selected.
System anti-freeze
If plate heat exchanger is frozen, the exchanger will be damaged; in addition, this kind of damage is out of
guarantee, so it should be specially noticed. Users should pay special attention to the three points below:
1. When there is a long-term vacancy with low outdoor Temp Water in waterside heat exchanger should be
drained out if the Temp below 0 .
℃
2. When running
If the chilled-water flow switch and anti-freeze Temp Sensor are invalid, water pipeline will be frozen, so the
wire of water flow switch must apply to the “wiring principle figure”
3. When maintaining
It is possible to freeze waterside heat exchanger when recharging and discharging refrigerant. Whenever
the pressure of the refrigerant is below 0.4Mpa, freezing would happen. So it is necessary to drained out all
of the water or keeps the water flowing.