Method of controlling a variable delivery pump fitted to a heating system

1. Method of controlling a variable delivery pump fitted to a heating system comprising:

a heat exchanger connected to two circuits of fluids, and wherein a first fluid coming from a primary circuit transmits heat energy to a second fluid coming from a secondary circuit, said 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 provided at the output of the heat exchanger and measuring a first temperature of the second fluid coming from the secondary circuit;

a second temperature sensor arranged at the output of the heat exchanger and measuring a second temperature of the first fluid coming from a primary circuit;

a control unit electrically connected to said first and second temperature sensors said sensors generating electrical signals as functions of the temperatures and constituting electrical input signals of the control unit, said control unit being capable of generating at output an instruction for controlling the variable delivery pump;

wherein the instruction for controlling the variable delivery pump is generated by comparing each first and second temperature respectively relative to first and second threshold values, and in that:

when said first and second temperatures are simultaneously below the first and second threshold values respectively the rated voltage of the control instruction signal increases in order to step up the delivery of the pump, and;

when the first and second temperatures are simultaneously higher than the first and second threshold values respectively the rated voltage of the control instruction signal decreases in order to reduce the delivery of the pump.

2. Method as claimed in claim 1 , wherein the first threshold value is a function of the thermal demands of a user on the secondary circuit.

3. Method as claimed in claim 1 , wherein the heating system comprises a third temperature sensor provided at the input of the heat exchanger and measuring a third temperature of the second fluid coming from the secondary circuit, and in that the second threshold value is a function of the third temperature of the second fluid.

4. Method as claimed in claim 3 , wherein the second threshold value is equal to the sum between the third temperature and a predetermined value dependent on the performance of said heat exchanger.

5. Method as claimed in claim 4 , wherein said predetermined value is between 5° C. and 25° C.

6. Method as claimed in claim 5 , wherein said predetermined value is more specifically between 10° C. and 20° C.

7. Method as claimed in claim 1 , wherein the rated voltage of the instruction signal for controlling the pump is variable between 0 and 10 Volt.

8. Method as claimed in claim 1 , wherein the rated voltage of the instruction signal for controlling the pump is a function of the rated voltage of at least one of the two signals coming from the first and second temperature sensors.

9. Method as claimed in claim 8 , wherein the rated voltage of the signal coming from the first temperature sensor is compared with the rated voltage of the signal coming from the second temperature sensor and in that the rated voltage of the instruction signal for controlling the pump is generated as a function of the smallest rated voltage of the two signals coming from the first and second temperature sensors.

10. Method as claimed in claim 1 , wherein the control unit controls a three-way valve provided on the primary circuit at the input of the exchanger, said three-way valve being capable of mixing the first fluid reaching the input of the heat exchanger with a portion of the first fluid coming from the output of the exchanger via the return loop.

11. Method as claimed in claim 10 , wherein the rated voltage of the instruction signal for controlling the three-way valve is a function of the rated voltage of the signal coming from the first temperature sensor.

12. Method as claimed in claim 11 , wherein the heating system comprises a fourth temperature sensor provided at the input of the heat exchanger and measuring a fourth temperature of the first fluid coming from the primary circuit, and in that the rated voltage of the instruction signal for controlling the three-way valve is a function of the rated voltage of the signal coming from the fourth temperature sensor.

13. Method as claimed in claim 12 , wherein the rated voltage of the signal coming from the first temperature sensor is compared with the rated voltage of the signal coming from the fourth temperature sensor and in that the rated voltage of the instruction signal for controlling the three-way valve is generated as a function of the smallest rated voltage of the two signals coming from the first and fourth temperature sensors.

14. Method as claimed in claim 1 , wherein the control unit controls a two-way valve provided on the primary circuit downstream from the return loop, said two-way valve being capable of orientating the first fluid coming from the output of the exchanger in the direction of the input of the heat exchanger via the return loop.

15. Method as claimed in claim 14 , wherein the rated voltage of the instruction signal for controlling the two-way valve is a function of the rated voltage of the signal coming from the first temperature sensor.

16. Method as claimed in claim 15 , wherein the heating system comprises a fourth temperature sensor provided at the input of the heat exchanger and measuring a fourth temperature of the first fluid coming from the primary circuit, and in that the rated voltage of the instruction signal for controlling the two-way valve is a function of the rated voltage of the signal coming from the fourth temperature sensor.

17. Method as claimed in claim 16 , wherein the rated voltage of the signal coming from the first temperature sensor is compared with the rated voltage of the signal coming from the fourth temperature sensor and in that the rated voltage of the instruction signal for controlling the two-way valve is generated as a function of the smallest rated voltage of the two signals coming from the first and fourth temperature sensors.