A medical fluid machine includes (i) a pump that pumps a medical fluid and (ii) a heater that heats the medical fluid, the heater including an electrically insulative housing, at least one flat sheet of electrically conductive material suitable for contacting the medical fluid, the sheet disposed within the insulative housing, the sheet defining a flow path for the medical fluid in which the medical fluid changes direction at least one time, a primary coil of a transformer located outside the insulative housing, the primary coil configured to induce a current into the at least one conductive sheet, creating heat that may be transferred to the medical fluid.
