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. A6 (4F2, C6)
2. A6 Saloon (4F2, C6)
3. A6 / S6 (4F2, C6)
4. A4 (8EC, B7)
5. A4 Saloon (8EC, B7)
6. A4 / S4 (8EC, B7)
7. A4 Avant (8ED, B7)
8. A4 / S4 Avant (8ED, B7)
9. A6 Avant (4F5, C6)
10. A8 (4E2, 4E8)
11. A8 Saloon (4E2, 4E8)
12. A8 / S8 (4E2, 4E8)
13. A8L (4E2, 4E8)
14. A4 Convertible (8H7, B6, 8HE, B7)
15. A4 / S4 Convertible (8H7, B6, 8HE, B7)
16. See more in applications

The principle of the thermostat work

The classic METZGER 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.