Utilizes electronic expansion valve to precisely Manage the circulation of R290 refrigerant in to the evaporator as well as a four-way valve to divert the refrigerant flow with the defrost Procedure Many of the upkeep demands for air source heat pumps reflect that of conventional air con and furnace installations, https://minibookmarking.com/story20571842/r290-air-source-heat-pump-no-further-a-mystery