Thermostat inspection

Inspect the thermostat in the following procedures:

1. 1
   remove the thermostat. Refer to “thermostat removal and installation” .
2. 2
   Inspect the thermostat pellet for signs of cracking.

   

3. Test the thermostat at the bench for control action.

• do not contact the thermostat (1) and column thermometer (2) with a pan.
• As the thermostat operating response to water temperature change is gradual, do not raise water temperature too quickly.
• The thermostat with its valve open even slightly under normal temperature must be replaced.

1. 1
   Immerse the thermostat (1) in the water contained in a beaker and note that the immersed thermostat is in suspension.
2. 2
   Heat the water by placing the beaker on a stove and observe the rising temperature on a thermometer (2)

   

String Water

6. Read the thermometer just when opening the thermostat. If this reading, which is the temperature level at which the thermostat valve begins to open, is out of the standard value, replace the thermostat with a new one.

1. 1
   Keep on heating the water to raise its temperature.
2. 2
   Just when the water temperature reaches specified value, the thermostat valve should have been lifted by at least 8 mm (0.31 In). A thermostat failing to satisfy either of the two requirements (start-to-open temperature and valve lift) must be replaced.

9. Install the thermostat. Refer to “thermostat removal and installation” .