Abstract: Method of controlling a variable delivery pump fitted to a heating system comprising: a heat exchanger connected to two circuits of fluids, the variable delivery pump making it possible to vary the flow-rate of the first fluid inside the heat exchanger; a return loop on the primary circuit allowing the first fluid reaching the input of the heat exchanger to mix with a portion of the first fluid coming from the output of the exchanger; a first temperature sensor measuring a temperature of the second fluid coming from the secondary circuit; a second temperature sensor measuring a temperature of the first fluid coming from a primary circuit; a control unit electrically connected to the first and second temperature sensors, the sensors generating electrical signals as functions of the temperatures and constituting electrical input signals of the control unit.