Gree VERSATI III Series, Service Manual

Page: 35 / 135

Unit Control
tank will stop. Then, the main unit will resume normal running when this error is eliminated.
5. The temperature sensor at the economizer is used to detect the temperature of the economizer
after throttling via the electrostatic expansion 2. Under the Heating or Hot Water mode, this sensor and
that at the economizer outlet both are used to control the opening angle of the electrostatic expansion
valve 2. Under the Cooling mode, the electrostatic expansion valve 2 is fully closed.
6. The temperature sensor at the economizer outlet is used to detect the tmpeature of the outlet of the
economizer. Unde the Heating or Hot Water mode, this sensor and that at the economser inlet both are
used to control the opening angle of the electrostatic expansion valve 2. Under the Cooling mode, the
electrostatic expansion valve 2 is fully closed.
7. The high pressure is detected by the sensor installed at the discharge pipe of the compressor, the
low pressure is detected by the sensor installed at the suction pipe of the compressor, and the
enthalpy-adding pressure is detected by the sensor installed at the enthalpy-adding pipe. The first one is
mainly used for high pressure protection, the second one is mainly used to control defrosting, freeze
protection and superheating degree, and all of three are used to together to control the intermediate
pressure ratio of the compressor. When any of these sensors fails, it will be displayed at the controller,
all loads except the water pump of the solar system and the electric heater of the water tank will stop.
Among them, the water pump will stop 120 seconds later than the compressor. Then, the main unit will
resume normal running when this error is eliminated.
8. The return water temperature of the plate heat exchanger is detected by the sensor installed at the
inlet pipe of the plate heat exchanger, which is mainly used for freeze protection. When this sensor fails,
this error will be displayed at the controller but the unit will resume normal operation.
9. The supply water temperature of the plate heat exchanger is detected by the sensor installed at the
outlet pipe of the plate heat exchanger, which is mainly used for freeze protection at the water side.
When this sensor fails, this error will be displayed at the controller and the unit will continues to operate.
10. The optional water temperature is detected by the sensor installed at the outlet pipe of the optional
E-heater, which is mainly used to control the supply water temperature. When this sensor fails, this error
will be displayed at the controller, all loads except the electric heater of the water tank will stop (the
2-way electric and 3-way electric valve will be closed).
11. The tempeaure sensor for the vapor line is used to detect the temperature of the vapor refrigerant
line. Under the Cooling mode, it and that for the liquid line together are used to control the opening angle
of the electrostatic expansion valve 1.
12. The tempeaure sensor for the liquid line is used to detect the temperature of the liquid refrigerant
line. Under the Cooling mode, it and that for the vapor line together are used to control the opening angle
of the electrostatic expansion valve 1.
13. The hi-pressure switch is used to judge the system pressure. When the pressure is too high, this
switch will disconnect and the unit will shut down.
14. The flow switch of the main unit is mainly used to judge the water flow. When the flow rate is too
low, this switch will be disconnected; all loads except the water tank heater and the water pump of the
solar system will stop. This error will be displayed at the controller and will be unrecoverable. The unit
can restart only when it is repowered on and this error does not be displayed again.
Items from 1~14 listed above are control parameters input by the main unit.
15. The water tank temperature is detected by sensors immersed inside the water tank. These
sensors can be divided into two groups. Group 1 is used to control the water tank temperature and group
2 is used to display the water tank temperature. When group 1 fails at the heating mode, this error will be
displayed at the controller, and all loads except the water pump of the main unit will stop. When group 2
fails, this error also will be displayed at the controller but the unit continues normal operation.