DE3203964

In a line bus (12) of a hot-water heating system with at least one forward-run line (24) and one return-run line (25), possibly also an added return-run line (69), there are connected in at the branching-off points for branch lines, in particular the connections for floor heating elements (27, 29, 31), branching-off units (14), the housing (32) of which has two branch chambers (41, 42), which lie transversely to the direction of flow, with pipe connection pieces (42 to 46) arranged on the outside on both sides. These branching-off units can also form, with heat-exchanger elements (27, 29, 31), independent built-in units. Their housing is passed through by three tube sleeves (51-53) which are connected into the individual lines and have in each branch chamber a lateral opening (56) which can be completely or partially closed by a throttle element (61). In this manner, it is possible at each branching-off point to divert a possibly preset part of the heat transfer medium out of the forward-run line (24) via the branch chambers (41), the heating element (27, 29, 31) and the branch chamber (42) into the added return-run line (69) or directly into the return-run line (25). As the added return-run line (69) is closed at both ends although its branching-off opening (59) is constantly open to the branch chamber (42), the heat transfer medium flows out of its end likewise through the branching-off opening (55) into the return-run line (25).