Abstract: A device for indicating and regulating the flow volume in a fluid circuit of a heating or cooling system is provided. The device includes a housing having a lower valve part, a conical bore, and a sealing seat. The device further includes an indicating element having a hollow-cylindrical inspection glass with a closed end, an open end, an indicator plunger axially movable therein and stressed by means of a spring. A regulating cone is attached to the open end of the inspection glass, whereby the free end of the indicator plunger is guided through the regulating cone and bears a flow body immersed in the conical bore. Also, the regulating cone has slots distributed at the periphery and extending to the indicator plunger.