The invention relates to a device for heating an air flow, in particular for a motor vehicle, comprising a frame which extends substantially in a plane, at least one heating section, which is held on the frame and which can be traversed by a first, heatable partial air flow, with an electrical heating element, in particular PTC element, and with at least one flow resistance element which is arranged in the plane adjacent to the heating section and which is held on the frame and which can be traversed by a second, non-heatable partial air flow, wherein a flow means is provided on the device, by means of which flow means the two partial air flows are mixed downstream of the device.