A heat exchanger element, in particular for inserting into a wastewater pipeline extending in a longitudinal direction, comprising a heat exchanger chamber for receiving a heat exchanger fluid, said chamber having an upper shell portion and a lower shell portion distanced therefrom, wherein an outer side of the upper shell portion is configured so as to come into contact with wastewater, at least in portions, in order to absorb heat from the wastewater, and wherein an inner side of the upper shell portion is configured so as to come into contact with the heat exchanger fluid, at least in portions, in order to emit the heat to the heat exchanger fluid, wherein an inflow of the heat exchanger chamber is fluidically connectable to an outlet of a feed line portion and an outflow of the heat exchanger chamber is fluidically connectable to an inlet of a return line portion, and wherein the inflow of the heat exchanger chamber is fluidically connectable selectively to an outflow of a heat exchanger chamber of a further heat exchanger element and the outflow of the heat exchanger chamber is fluidically connectable selectively to an inflow of a heat exchanger chamber of a further heat exchanger element, further comprising a feed-side connection pipe, which is provided on the feed side on the heat exchanger chamber and the outflow of which is fluidically connected to the inflow of the heat exchanger chamber, and a return-side connection pipe, which is provided on the return side on the heat exchanger chamber and the inflow of which is fluidically connected to the outflow of the heat exchanger chamber, wherein an entry opening of the feed-side connection pipe is fluidically connectable to the outlet of the feed line portion or to the exit opening of the return-side connection pipe of the further heat exchanger element, and wherein an exit opening of the return-side connection pipe is fluidically connectable to the inlet of the return-line portion or to the inlet opening of the feed-side connection pipe of the further heat exchanger element, wherein the entry opening of the feed-side connection pipe is fluidically connectable articulatedly to the exit opening of the return-side connection pipe of the further heat exchanger element and/or the exit opening of the return-side connection pipe is fluidically connectable articulatedly to the entry opening of the feed-side connection pipe of the further heat exchanger element, in order to provide a mutual pivotability of the heat exchanger element and the further heat exchanger element about a centre axis of the corresponding connection pipe (4, 6). a heat exchanger chamber for receiving a heat exchanger fluid, said chamber having an upper shell portion and a lower shell portion distanced therefrom, wherein an outer side of the upper shell portion is configured so as to come into contact with wastewater, at least in portions, in order to absorb heat from the wastewater, and wherein an inner side of the upper shell portion is configured so as to come into contact with the heat exchanger fluid, at least in portions, in order to emit the heat to the heat exchanger fluid, wherein an inflow of the heat exchanger chamber is fluidically connectable to an outlet of a feed line portion and an outflow of the heat exchanger chamber is fluidically connectable to an inlet of a return line portion, and wherein the inflow of the heat exchanger chamber is fluidically connectable selectively to an outflow of a heat exchanger chamber of a further heat exchanger element and the outflow of the heat exchanger chamber is fluidically connectable selectively to an inflow of a heat exchanger chamber of a further heat exchanger element, further comprising a feed-side connection pipe, which is provided on the feed side on the heat exchanger chamber and the outflow of which is fluidically connected to the inflow of the heat exchanger chamber, and a return-side connection pipe, which is provided on the return side on the heat exchanger chamber and the inflow of which is fluidically connected to the outflow of the heat exchanger chamber, wherein an entry opening of the feed-side connection pipe is fluidically connectable to the outlet of the feed line portion or to the exit opening of the return-side connection pipe of the further heat exchanger element, and wherein an exit opening of the return-side connection pipe is fluidically connectable to the inlet of the return-line portion or to the inlet opening of the feed-side connection pipe of the further heat exchanger element, wherein the entry opening of the feed-side connection pipe is fluidically connectable articulatedly to the exit opening of the return-side connection pipe of the further heat exchanger element and/or the exit opening of the return-side connection pipe is fluidically connectable articulatedly to the entry opening of the feed-side connection pipe of the further heat exchanger element,