A connection assembly for a heating system, in particular an underfloor heating system, - with at least one tube holder and - with a tube section of a heat exchanger tube, which tube section extends along a straight horizontal axis (X1, X2, X3, X4) in said tube holder and is held by the at least one tube holder in a form-locking and/or force-locking manner, - wherein the tube holder has a base support (2.1) having a horizontally extending upper surface (2.1a) and projections (2.2, 2.3, 2.4, 2.5) extending from said upper surface (2.1a), - wherein the projections (2.2, 2.3, 2.4, 2.5) have side walls (2.2a, 2.2b, 2.2c, 2.3a, 2.3b, 2.3c, 2.4a, 2.4b, 2.4c, 2.5a, 2.5b, 2.5c) having tube contact surfaces, wherein at least two side walls (2.2a, 2.2b, 2.2c, 2.3a, 2.3b, 2.3c, 2.4a, 2.4b, 2.4c, 2.5a, 2.5b, 2.5c) of the projections (2.2, 2.3, 2.4, 2.5) contact the tube section with the tube contact surfaces and fix it in a predefined tube position (L1, L2, L3, L4), - wherein the side walls (2.2a, 2.2b, 2.2c, 2.3a, 2.3b, 2.3c, 2.4a, 2.4b, 2.4c, 2.5a, 2.5b, 2.5c) having the tube contact surfaces are arranged in the tube holder in such a manner that the tube section can be held in a form-locking and/or force-locking manner in a plurality of possible tube positions (L1, L2, L3, L4), wherein, in each of the tube positions (L1, L2, L3, L4), the tube section extends along a different straight horizontal axis (X1, X2, X3, X4) in the tube holder, - wherein the ratio of the number of side walls (2.2a, 2.2b, 2.2c, 2.3a, 2.3b, 2.3c, 2.4a, 2.4b, 2.4c, 2.5a, 2.5b, 2.5c) having tube contact surfaces to the number of possible tube positions (L1, L2, L3, L4) is less than 4, characterized in that four projections (2.2, 2.3, 2.4, 2.5) are provided, each of which has more than two side walls (2.2a, 2.2b, 2.2c, 2.3a, 2.3b, 2.3c, 2.4a, 2.4b, 2.4c, 2.5a, 2.5b, 2.5c) having tube contact surfaces. - with at least one tube holder and - with a tube section of a heat exchanger tube, which tube section extends along a straight horizontal axis (X1, X2, X3, X4) in said tube holder and is held by the at least one tube holder in a form-locking and/or force-locking manner, - wherein the tube holder has a base support (2.1) having a horizontally extending upper surface (2.1a) and projections (2.2, 2.3, 2.4, 2.5) extending from said upper surface (2.1a), - wherein the projections (2.2, 2.3, 2.4, 2.5) have side walls (2.2a, 2.2b, 2.2c, 2.3a, 2.3b, 2.3c, 2.4a, 2.4b, 2.4c, 2.5a, 2.5b, 2.5c) having tube contact surfaces, wherein at least two side walls (2.2a, 2.2b, 2.2c, 2.3a, 2.3b, 2.3c, 2.4a, 2.4b, 2.4c, 2.5a, 2.5b, 2.5c) of the projections (2.2, 2.3, 2.4, 2.5) contact the tube section with the tube contact surfaces and fix it in a predefined tube position (L1, L2, L3, L4), - wherein the side walls (2.2a, 2.2b, 2.2c, 2.3a, 2.3b, 2.3c, 2.4a, 2.4b, 2.4c, 2.5a, 2.5b, 2.5c) having the tube contact surfaces are arranged in the tube holder in such a manner that the tube section can be held in a form-locking and/or force-locking manner in a plurality of possible tube positions (L1, L2, L3, L4), wherein, in each of the tube positions (L1, L2, L3, L4), the tube section extends along a different straight horizontal axis (X1, X2, X3, X4) in the tube holder, - wherein the ratio of the number of side walls (2.2a, 2.2b, 2.2c, 2.3a, 2.3b, 2.3c, 2.4a, 2.4b, 2.4c, 2.5a, 2.5b, 2.5c) having tube contact surfaces to the number of possible tube positions (L1, L2, L3, L4) is less than 4,