Circuit assembly

The arrangement (1) has a protection device e.g. valves (7, 17) and thermostats, arranged in an engine-internal bypass (6) for de-throttling an exhaust gas manifold (11). Coolant volume flow is circulated into cooling and heat circuit sections (2, 8). A bypass e.g. 3-way bypass valve and hose, is arranged as a branch parallel to a heat exchanger (9) in the heating section for flowing into the cooling section. The cooling section passes through a coolant radiator (3), an engine block (4) and the manifold. The heat section passes through the exchanger, the engine block and the manifold.