MAXA R407C - Page 31

CD 30 ÷ 520
31
 In the cold winter, if the unit stops at night, the water in plate heat exchanger and pipeline may
freeze, which will damage the device and pipeline. To prevent freezing, it is absolutely
forbidden to switch off the power of the unit (the unit has auto anti-freeze function). If it is still
likely to freeze, it must drain away all water in the water pipe. If it is difficult to drain water, some
anti-freeze mixture such as glycol or propylene glycol can be adopted. Notice: it is absolutely
forbidden to use salt mixture, which would corrode the system and cause damage.
 When using industrial water as chilled-water, it seldom scales. However if adopting the water
from well or river, it will produce much deposit such as scale and sand. So the water should
be filtered and intenerated through some equipment before flowing into the freeze-water
system. If there is sand or mud deposited in the evaporator, it will jam the flow of chilled-water,
which will cause freezing. So it is important to test the water’s PH value, conductivity,
concentration of chlorine hydronium, concentration of sulfur hydronium, etc.
The following is the standard of water quality:
PH value:
6.58.0
Total rigidity:
˘50ppm
Conductivity:
˘200V/cm˄25ć˅
Sulfur hydronium:
None
Chlorine
hydronium:
˘50ppm
Ammonia hydronium:
None
Vitriol hydronium:
˘50ppm xi˖ ˘30ppm
Iron thickness
˘0.3ppm
Natrium hydronium:
None
Calcium hydronium:
˘50ppm
12. Wiring
All wiring installation must be done by qualified person.
Precautions:
 The power supply must be stable when the unit is running. Considering all voltage-drop factors,
the running voltage needed by the system should be kept within fˍˌˁ range of the rating.
Too high or too low voltage will have bad effect on the unit.
 The difference of voltage among phases should be not more than ˎˁ of the rating, and the
max current difference among phases should be less than 3% the rating to prevent compressor
from overheating.
 The frequency of the power should be kept within fˎˁof the rating.
 The lowest starting voltage should be more than 90% of the rating.
 The compressor may be unable to start if the wire is too longer, so the length of the wire should
be limited to ensure the voltage-drop between the two ends of the wire is less than 2% of the