This document is applicable to prefabricated devices for heat recovery from shower wastewater, consisting of a double-walled heat exchanger with a vented primary side and pressurized secondary side, capable of achieving a minimum nominal flow rate on the secondary side of 12,5 l/min. Requirements for drinking water safety, durability, and general product design and associated testing are described. They do not have to be installed directly at the shower, but can be used at any point in the shower wastewater system within the building. This document is applicable for the following operating conditions: Primary side: - maximum operating pressure up to 250 kPa; - maximum permanent temperature up to 40 °C. Secondary side: - maximum operating pressure up to 1000 kPa (according to DIN EN 806 (all parts)); - maximum permanent temperature up to 40 °C; - maximum pressure drop between inlet and outlet on the secondary side of 60 kPa at nominal flow rate This document is not applicable to devices for heat recovery from wastewater with storage tank.