Employs Digital enlargement valve to exactly Command the movement of R290 refrigerant in the evaporator in addition to a 4-way valve to divert the refrigerant stream for the defrost Procedure The ECOMOD 290HT choice of monobloc air source heat pumps come in three chassis measurements and five outputs: 15kW, 18kW, https://purethermal.co.uk/media-news/q4-launch-lithium-large-capacity-r290-ashp-from-pure-thermal-and-enerblue/