A modular system for exhaust heat recovery devices has heat exchangers which differ by different external dimensions, in particular different cross-sections, and identically configured exhaust gas carrying housings into each of which one of the heat exchangers can be introduced. Various tubular adapters are adapted to the external dimensions of the heat exchangers and are used to fasten the associated heat exchanger at its connection ends to the exhaust gas carrying housing. Furthermore, a tubular adapter for a corresponding modular system and a vehicle which has a corresponding exhaust heat recovery device are provided.