Abstract: A device for measuring or controlling a property of a flow medium comprises a conduit which carries a flow medium. A choke element located in the conduit has a first open operating position and a second closed operating position. A driver drives the choke element from one operating position to the other. A pressure sensor measures the difference in pressure before and after the choke element in said conduit. A processor responsive to the pressure difference calculates a flow or thermal property of the flow medium. The processor comprises an input for receiving a continuous control signal which indicates a desired value of a flow or thermal property of the flow medium and a converter for converting the continuous control signal into a pulse-pause signal for controlling the driver.

Abstract: A heat circuit comprises an initial conduit containing a flow medium and a return conduit. A choke element located in a conduit such as the initial conduit of a heat circuit serves to control the flow of the flow medium. The choke element has several active positions in which openings having differently sized cross-sections are inserted into the path of flow. The choke element is moved by a drive so that a particular position of the choke is active. A differential pressure sensor measures the presure difference before and after the choke element. A computer resposive to the differential pressure sensor controls the drive so that a particular cross-section of the choke element takes effect and the flow of the medium is measured with sufficient precision over a wide measuring range. The inventive arrangement may also include a temperature sensor for measuring the temperature difference between the initial and return conduits.