Uses electronic enlargement valve to exactly control the movement of R290 refrigerant to the evaporator as well as a four-way valve to divert the refrigerant stream for your defrost operation You'll need Room - exterior for your pump and inside for any drinking water storage tank. Some heat pumps might https://purethermal.co.uk/media-news/q4-launch-lithium-large-capacity-r290-ashp-from-pure-thermal-and-enerblue/