An aerosol-generating system includes a cartridge (20), comprising a liquid storage portion comprising a housing (24) for holding a liquid aerosol-forming substrate, the housing having an opening and a heater assembly (30) comprising at least one heater element (36) fixed to the housing and extending across the opening of the housing, wherein the width of the at least one heater element of the heater assembly is smaller than the width of the opening of the housing. In examples, the heater element is spaced from the periphery of the opening, leading to more efficient heating and aerosol production.
