... unit included 4 way valve, liquid storage tank, pcb, heat exchanger, auxiliary heater, pressure gage, compressor inside ... the indoor unit 2.auxiliary heater for option, you can choose from 1.5Kw~7. ... , auxiliary heater also work during defrosting, our PCB with the control of the auxiliary heater, that ... type EVI DC inverter heat pump for cold area house heating and domestic hot waer