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Key components:
1. Compressor
Maintains pressure differential between high and low pressure sides of the refrigerant system.
2. Fan:
Ventilates the air side heat exchanger.
3. Oil separator:
Separates oil from gas refrigerant pumped out of the compressor and quickly returns it to the compressor. Separation
efficiency is up to 99%.
4. Accumulator:
Stores liquid refrigerant and oil to protect the compressor from liquid hammering.
5. Electronic expansion valve (EXVA/B/C):
Controls refrigerant flow and reduces refrigerant pressure.
6. Four-way valve:
Controls refrigerant flow direction. Closed in cooling mode and open in heating mode. When closed, the air side heat
exchanger functions as a condenser and water side heat exchanger functions as an evaporator; when open, the air
side heat exchanger functions as an evaporator and water side heat exchanger function as a condenser.
7. High and low pressure switches:
Regulate refrigerant system pressure. When the refrigerant system pressure rises above the upper limit or falls below
the lower limit, the high or low pressure switches turn off, stopping the compressor.
8. Discharge temperature switch:
Protects the compressor from abnormally high temperatures and transient spikes in temperature.
9. Air purge valve:
Automatically removes air from the water circuit.
10. Safety valve:
Prevents excessive water pressure by opening at 43.5psi (3bar) and discharging water from the water circuit.
11. Water flow switch:
Detects water flow rate to protect the compressor and water pump in the event of insufficient water flow.
12. Water pump:
Circulates water in the water circuit.
13. Pressure sensor:
Measures refrigerant system pressure.
14. Crankcase heater:
Prevents refrigerant from mixing with compressor oil when the compressors are stopped.
15. Water side heat exchanger electric heater:
Protects the water side heat exchanger from ice formation.
16. Water flow switch electric heater:
Provides additional heating when heating capacity provided by the heat pump is insufficient due to low ambient
temperatures, it also protects external water pipes from freezing.
17. Solenoid valve SV4:
Returns oil to the compressor. It opens after 17 minutes of compressor operation, closes after 3 minutes, then opens
again for 3 minutes at 17 minute increments.
18. Plate heat exchanger:
In cooling mode, it can improve super-cooling degree and the super-cooled refrigerant can achieve better heat
exchange in indoor side. In heating mode, the refrigerant comes from the plate heat exchanger going to the
compressor can enhance the refrigerant enthalpy and improve the heating capacity in low ambient temperature.
Refrigerant volume in plate heat exchanger is controlled according to temperature different between plate heat
exchanger inlet and outlet.
