Method of regulating a central or district heating plant by means of a differential pressure valve, and unit for working method

A method for regulating a central or zone heating plant, the method including circulating a heat carrying fluid from an upstream supply line, through at least one radiator provided with a thermostat valve in each of a plurality of rooms in a building, to a downstream return lines;

• placing a differential pressure valve in the downstream return line so that the heat carrying fluid returning from the radiators flows through a passage between an inlet and an outlet of the differential pressure valve, the differential pressure valve having a closing device controlled by a membrane for regulating the flow of the heat carrying fluid through the passage between the inlet and the outlet;
• providing a throttle in the return line upstream of the closing device;
• applying a pressure obtained from a first location upstream of the throttle to a first side of the membrane;
• and applying a pressure obtained from a second location downstream of the throttle to a second side of the membrane opposite to the first side, wherein the improvement comprises locating the adjustable throttle in the passage of the differential pressure valve between the inlet and the closing device, and adjusting the throttle to allow a maximum amount of fluid to pass through the differential pressure valve, regardless of the state of distribution of pressure in the plant.