A cartridge for an aerosol-generating system is provided, the cartridge including: a liquid storage portion including a housing with a first opening, to contain a liquid aerosol-forming substrate; and a heater assembly including an electrically insulating support having a second opening, an electrical heating element supported by the insulating support and to heat the substrate to form an aerosol, and first and second electrically conductive contact portions disposed at opposite sides of the second opening and to connect to electrical connectors of a battery to supply power to the heater assembly, and a capillary material having first and second faces, the first face being in physical contact with the heating element and the second face being opposite the first face, the capillary material to convey the substrate to the heating element by capillary action, the heater assembly being connected to the housing of the liquid storage portion.