Abstract: A discharge connection, an inlet pipe, an outlet pipe and a drain channel are provided. On an outer end, the outlet pipe has an outwardly closing check valve with a valve body and a valve seat. The outlet pipe has a first coupling geometry at the outer end, which can be interlockingly connected to a conduit coupling. The check valve is designed to be moved from the valve seat into a open position, spaced apart from same, by a profile element projecting into the outer end.