Thermostat, coolant - 819741 VALEO

Thermostat is a device for maintaining a static (constant) temperature, as its name implies. There are thermostats of different designs in many devices and mechanisms, from water heaters to refrigerators. There is also a thermostat in a car's internal combustion engine (liquid-cooled, of course). In a car, the thermostat regulates the temperature of the coolant (antifreeze): it accelerates the warm-up of a cold engine and provides heat removal from the hot one. Therefore, the engine works more efficiently and more comfortably for the driver, especially in winter - without a thermostat, the stove would usually blew cold air.

1. A4 (8K2, B8)
2. A4 Saloon (8K2, B8)
3. A4 / S4 (8K2, B8)
4. A4 Avant (8K5, B8)
5. LEON ST (5F8)
6. A5 (8T3)
7. A5 / S5 (8T3)
8. A5 Convertible (8F7)
9. A5 / S5 Convertible (8F7)
10. A5 Sportback (8TA)
11. A5 / S5 Sportback (8TA)
12. Q5 (8RB)
13. Q5 SUV (8RB)
14. A3 Limousine (8VS, 8VM)
15. A3 / S3 Limousine (8VS, 8VM)
16. A3 (8V1, 8VK)
17. A3 / S3 (8V1, 8VK)
18. A3 Sportback (8VA, 8VF)
19. LEON (5F1)
20. OCTAVIA III (5E3, NL3, NR3)
21. See more in applications

The principle of the thermostat work

The classic VALEO brand Thermostat, coolant is a movable valve that moves due to a change in the external environment - heating or cooling of antifreeze. The thermostat is made of a thermoelement filled with a substance resembling wax in structure - ceresin, with the addition of copper powder, graphite or aluminum for better thermal conductivity. At a certain temperature of the antifreeze, ceresin expands, opening the thermostat valve. When the motor cools down, ceresin contracts and the thermostat closes again.