Abstract: A recuperator including neighbouring sheets between which flow passages for air are formed. The sheets are provided with a corrugated profile including peaks, troughs and straight flanks. The peaks and troughs of a sheet are situated at an equal distance from a central plane of the sheet. Neighbouring flanks are directly connected to each other via a peak or trough. Between neighbouring flanks, first and second passage duct parts are formed which are each delimited at one end by a peak or trough and which are open at the end situated opposite the peak. In a direction at right angles to the central plane, the peaks and troughs associated with neighbouring sheets are aligned with respect to each other in such a way that first passage duct parts of a sheet and second passage duct parts associated with a neighbouring sheet are in communication with each other via connecting passage parts which extend between the troughs associated with the one sheet and peaks associated with the other sheet.