The present invention relates to a Rankine system comprising a valve including a valve member. The valve member is provided with a valve controlling element in the form of an elongated tapered end portion with a tip end facing the duct, wherein the tapered end portion is arranged to be inserted through the opening and into the duct as the valve member is moved towards the valve seat. The actuator is configured to hold the valve member in at least one intermediate position between the first and second end positions, where the tapered end portion occupies a portion of a cross-sectional fluid through-flow area defined by the duct so as to partly restrict a flow of fluid through the duct.