Uses electronic growth valve to exactly Command the flow of R290 refrigerant in to the evaporator in addition to a four-way valve to divert the refrigerant movement to the defrost Procedure Using electrical power, the pump compresses the liquid to enhance its temperature. It then condenses back into a liquid https://purethermal.co.uk/media-news/q4-launch-lithium-large-capacity-r290-ashp-from-pure-thermal-and-enerblue/