Midea MCCDH30A-TA3SL Technical & Service Manual Download

Page: 87 / 169

Air-cooled modular chiller unit

d. The pump installed in the water pipeline system should be equipped with starter. The pump will directly

press water into the heat exchanger of the water system.
e. The pipes and their ports must be independently supported but should not be supported on the unit.
f. The pipes and their ports of the heat exchanger should be easy to disassemble for operation and cleaning,

as well as inspection of port pipes of the evaporator.
g. The evaporator should be provided with a filter with more than 40 meshes per inch at site. The filter

should be installed near to the inlet port as much as possible, and be under heat preservation.
h. The by-pass pipes and by-pass valves as shown in the figure of “

Connection drawing of pipeline

system”

must be mounted for the heat exchanger, to facilitate cleaning of the outside system of water

passage before the unit is adjusted. During maintenance, the water passage of the heat exchanger can be

cut off without disturbing other heat exchangers.
i. The flexible ports should be adopted between the interface of the heat exchanger and on-site pipeline, to

reduce transfer of vibration to the building.
j. To facilitate maintenance, the inlet and outlet pipes should be provided with thermometer or manometer.

The unit is not equipped with pressure and temperature instruments, so they need to be purchased by the

user.
k. All low positions of the water system should be provided with drainage ports, to drain water in the

evaporator and the system completely; and all high positions should be supplied with discharge valves, to

facilitate expelling air from the pipeline. The discharge valves and drainage ports should not be under heat

preservation, to facilitate maintenance.
l. All possible water pipes in the system to be chilled should be under heat preservation, including inlet pipes

and flanges of the heat exchanger.
m. The outdoor chilled water pipelines should be wrapped with an auxiliary heating belt for heat preservation,

and the material of the auxiliary heat belt should be PE, EDPM, etc., with thickness of 20mm, to prevent the

pipelines from freezing and thus cracking under low temperature. The power supply of the heating belt

should be equipped with an independent fuse.
n. When the ambient temperature is lower than 2

℃

, and the unit will be not used for a long time, water inside

the unit should be drained. If the unit is not drained in winter, its power supply should not be cut off, and the

fan coils in the water system must be provided with three-way valves, to ensure smooth circulation of the

water system when the anti-freezing pump is started up in winter.
o. The common outlet pipelines of combined units should be provided with mixing water temperature sensor.
Warning:
● For the water pipeline network including filters and heat exchangers, dreg or dirt may seriously damages

the heat exchangers and water pipes.
● The installation persons or the users must ensure the quality of chilled water, and de-icing salt mixtures

and air should be excluded from the water system, since they may oxidize and corrode steel parts inside the

heat exchanger.

.2.2 Water Quality

※Water quality control

When industrial water is used as chilled water, little furring may occur; however, well water or river water,

used as chilled water, may cause much sediment, such as furring, sand, and so on. Therefore, well water or

river water must be filtered and softened in softening water equipment before flowing into chilled water
system. If sand and clay settle in the evaporator, circulation of chilled water may be blocked, and thus

leading to freezing accidents; if hardness of chilled water is too high, furring may occur easily, and the

devices may be corroded. Therefore, the quality of chilled water should be analyzed before being used, such

as PH value, conductivity, concentration of chloride ion, concentration of sulfide ion, and so on.

※

Applicable standard of water quality for the unit

value

Total

hardness

Conductivity

Sulfide

ion

Chloride