Systems of heat pump water heater works in sanitary hot water heating:
- Compressed by compressor, low pressure and low temperature refrigerant turns into high pressure and high temperature, and passes through reverse valve to condenser (Water Heat Exchanger); heat energy transferred to water and refrigerant turns into high pressure and low temperature liquid; and water was heated.
- Then refrigerant throttled by expansion valve and becomes bigger in size, changed to low temperature and low pressure refrigerant in partial liquid and partial gas status.
- Then liquid gas mixed refrigerant goes into evaporator Air Heat Exchanger); fan system blows air through the fin-tube air heat exchanger so that refrigerant will absorb heat from surrounding air and turn into gas status.
- Eventually, the refrigerant passes through reverse valve and goes into compressor and repeats the cycle.
- When system operates in heating mode in condition of cold weather, frost will be possibly formed on the surface of evaporator (Fin-tube Air Heat Exchanger) and reduce the heat absorption.
- Activation of defrost will depends on temperature and operating time.
- If defrost program activated, system will reverse to cooling, so that the frost on fin-tube air heat exchanger will be melted. During this process, fan does not rotate when system defrosting.
- When defrost program stop, system will switch back to heating.
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