8.17 Adjustable thermostat 8.17.1 General characteristics Thermostats are used to control and regulate the temperature of the washing water. Some thermostats are based on the fluid expansion effect, and their intervention temperatures can be adjusted. 1. Bulb 2. Capillary 3. Capillary sheath 4. Thermostat body 5. Contact Thermostats function according to the principle of the expansion of the fluid contained in the hydraulic circuit. When the bulb is heated, the liquid in the capillary tube expands against the membrane. The movement of the membrane actions a device that opens or closes the contacts.
The spindle can be used to adjust the temperature at which switching of the contacts occurs (0-90°C). 1. Bulb 2. Capillary 3. Regulation screw 4. Membrane 5. Rocker arm 6. Contact 8.17.2 Electrical symbol 8.17.3 Checking for efficiency 1. Use a tester to check that, when cold, the contacts are in the correct position (normally closed). 2. Heat the thermostat bulb and check for correct switching of the contacts. 3. Allow the thermostat to cool and check that the contacts return to their original position. 4. Check that the thermostat capillary is correctly secured to the tub and that the coils are present. SOI/DT 2002-05 eb 88 599 35 23-17