Abstract: System for drainage of surface water, the system comprises a number of tanks being connected to a main pipeline leading water to a recipient. Each tank has at least one outlet for leading water from the tank to the main pipeline, and a corresponding lid, the lid is limiting the outlet until the water is at a predetermined level in the tank. The system further comprises a check valve arranged downstream of the outlet of each tank, preventing water from entering the tank from the main pipeline, and at least one air bleeder valve and at least one siphonic drainage regulator arranged between a tank and the recipient.

Abstract: The present invention is to provide a system and a method for effectively preventing that gases/heat from an outlet are ascending from a gully and form ice, in addition to effectively drain liquids through a gully. The present invention is obtained by arranging a float so that said float and a portion of the gully define a closable opening for through flow, further arranged such that the float is preventing gases/heat from the outlet to ascend up from the gully and form ice and/or so that the float prevents that gas is drawn into the gully.