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. ASTRA H Estate Van (L70)
2. ASTRA H Van (L70)
3. GRANDE PUNTO (199_)
4. PUNTO (199_)
5. CROMA (194_)
6. SIGNUM Hatchback (Z03)
7. VECTRA C Estate (Z02)
8. VECTRA C (Z02)
9. VECTRA C GTS (Z02)
10. ASTRA H (A04)
11. ASTRA H Estate (A04)
12. ASTRA Mk V (H) (A04)
13. VECTRA Mk II (C) GTS (Z02)
14. VECTRA Mk II (C) (Z02)
15. SIGNUM (Z03)
16. VECTRA Mk II (C) Estate (Z02)
17. 9-3 (YS3F, E79, D79, D75)
18. 9-3 Saloon (YS3F, E79, D79, D75)
19. ASTRA H GTC (A04)
20. 9-3 Estate (E50)
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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.