Thermostat: Testing and Inspection

Thermostat Inspection

^ Make sure that air bleed valve (1) of thermostat is clean.
^ Check to make sure that valve seat (2) is free from foreign matters which would prevent valve from seating tight.
^ Check thermostat seal (3) for breakage, deterioration or any other damage.





^ Check thermostatic movement of wax pellet as follows:
a. Immerse thermostat (1) in water, and heat water gradually.
b. Check that valve starts to open at specific temperature.

Temperature at which valve begins to open 80 - 84°C (176 - 183°F)

Temperature at which valve become fully open 95 - 97°C (203 - 206°F)

Valve lift: More than 8 mm (0.31 in.) at 95°C (203°F)

If valve starts to open at a temperature substantially below or above specific temperature, thermostat unit should be replaced with a new one. Such a unit, if reused, will bring about overcooling or overheating tendency.