Uses electronic growth valve to precisely Regulate the movement of R290 refrigerant in the evaporator as well as a 4-way valve to divert the refrigerant circulation for the defrost Procedure The refrigerant in an air-source heat pump absorbs heat through the outside air and turns into a gasoline by way https://highkeysocial.com/story6018713/the-basic-principles-of-r290-propane-heat-pump