Learn how your appliance is supposed to operate so you can determine if it is malfunctioning.
On conventional ranges, the oven temperature is most often controlled by a hydraulic thermostat. That thermostat consists of an electrical switch box mounted in the control panel, a shaft which the temperature adjustment knob attaches onto and a sensor bulb connected to the control body via a capillary tube. The sensor bulb filled with gas is inserted into the oven cavity and held in place my clips. As the sensor is heated by the oven air temperature the gas inside the sensor bulb expands and is forced through the capillary tube to the thermostat body where it actuates electrical contacts which open and close in response to the changing temperatures. When open the thermostat contacts stop power from getting to the oven elements. When closed power is allowed to feed the elements where they generate heat.
Contrary to popular belief an oven does not maintain an exact temperature. The cycles of heating and not can allow the oven temperature to vary by 20 degrees above and below the set temperature. The result is an average oven temperature that the control is set for.
More complex oven designs like self cleaning models may also incorporate an oven selector switch. While the thermostat is responsible for cycling the heat in response to temperature, the selector switch can control whether it is the bake element or broil element doing the heating or both, as in a self clean cycle. There may be additional electrical relays involved in the actual switching of power to the elements depending on the design of the control system utilized in the particular model.
Most newer ranges and ovens use an electronic control system to regulate oven operations. Such a system consist of an electronic control in the control panel and an oven temperature sensor mounted in the oven cavity. The oven temperature sensor is a thermistor which changes resistance depending on ambient temperatures. The sensor is connected to the control by electrical wiring. The control reads the resistance changes in the sensor and reacts, opening and closing electrical relays to switch power to the oven elements on and off. In most cases those relays are an integral part of the electronic control although some control designs use a separate relay board to control the actual switching of power to the elements. On such a system wiring connects the relay board to the main electronic control board.
Electronic controls can be programmed to do all sorts of things it was not possible for a conventional hydraulic thermostat to do. An electronic control can turn the oven elements on at full power (240 volts), half power (120 volts) or mix and match power and element functioning in an attempt to create the best baking solution. Consult the technical data for your particular model to see exactly how your oven was designed to function.
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