Heat storage in engine cooling system

A heating and cooling system (1) for an internal combustion engine (2) and a method of controlling said heating and cooling system comprising a heat storage circuit (3) and a radiator circuit (4). The heat storage circuit comprising a heat storage container (30), in which engine coolant is stored and allowed to flow into and out of. The radiator circuit (4) comprising a radiator (40) for flow of the engine coolant and the radiator has a radiator inlet and a radiator outlet. The radiator inlet is connected via an upstream radiator conduit (43) to a coolant outlet of the engine. The radiator outlet is connected via a downstream radiator conduit (44) to a coolant inlet of the engine. A bypass conduit (45) is connected between the upstream radiator conduit and the downstream radiator conduit to allow coolant to bypass the radiator. A thermostat controlled valve (46) is arranged in the upstream radiator conduit at a coolant outlet of the engine and connected to the bypass conduit.