14
Test Operation & Troubleshooting & Maintenance
Flow Switch
It is used to prevent the heat exchanger from being
frozen owing to reduced water ow rate. When the
ow rate goes down to the point at which the ow
switch will act, the switch will trip off and the unit will
raise an alarm and shut down.
Three-pipe Liquid
Receiver
Three pipes are connected to two electrostatic
expansion valves and the enthalpy-adding port of the
compressor respectively. It is mainly used to further
reduce pressure of the refrigerant which has gone
through the rst-stage throttling and then vaporize
some refrigerant. The vaporized refrigerant will be
sucked in the compressor again so as to enhance the
heating performance of the system.
Safety Valve
It is used to prevent the pressure of circulation water
from increasing unusually. When the pressure is larger
than the set point (0.6MPa), this valve will open to
relieve water pressure.
Exhaust Valve
It is used to expel air trapped inside the water system
to make sure normal operation of the system. It is
usually installed at the highest point of the system.
5�3�2 Charging and Discharging of Refrigerant
he unit has been charged with refrigerant before delivery. Overcharging or undercharging will cause the
compressor to run improperly or be damaged. When refrigerant is required to be charged or discharged for
installation, maintenance and other reasons, please follow steps below and nominal charged volume on the
nameplate.
(1) Discharging: remove metal sheets of the outer casing, connect a hose to the charging valve and then
discharge refrigerant.
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