Modern ovens have an intricate control system for regulating the temperature. This puts the gas and electric ovens of today a step above the wood-burning ovens of yesteryear. Heat sensors and thermostats are part of the innovations in modern ovens to help regulate the temperature. Understanding how the two are related -- and are different -- will help you to service your oven if it needs repair or adjustments.
Heat Sensor Versus Thermostat
The heat sensor and thermostat are not the same. The heat sensor is like a thermometer that measures the heat inside the oven. The thermostat is an on-off switch to turn the heating element on or off depending on the results from the heat sensor. If you turn the oven to 500 degrees Fahrenheit to try to heat it to 300 degrees Fahrenheit faster, it will not work. The oven will not heat faster. The thermostat will not shut the heating element off until the the heat sensor indicates that the oven has reached 500 degrees Fahrenheit. Just set the oven to the needed temperature and be patient. You cannot speed the rate of heating.
How an Oven Works
Electric or gas ovens basically control their temperature through the relation between the heat sensor and the thermostat. The heat sensor has a small bulb filled with temperature-sensitive gas or liquid. Changes in the temperature inside the oven cause the liquid or gas in the bulb to expand. This triggers the thermostat to turn on or off. When the thermostat turns on, the heating element or burner inside the oven turns on until the heat sensor trips the thermostat to shut off the heat source because the oven has reached the needed temperature.
Testing the Thermostat
If you suspect the oven is not cooking at the correct temperature, the thermostat might need to be recalibrated. Preheat the oven and place an oven thermometer inside. If the temperature is between 25 and 50 degrees Fahrenheit off from the set temperature and the actual temperature, you can adjust the thermostat to recalibrate it. If the temperature difference is greater than 50 degrees Fahrenheit, you will need to replace both the heat sensor and the thermostat.
Adjusting the Thermostat
Use a Philip's screwdriver to adjust a thermostat that is slightly off. Pull the control knob off the front of the oven to locate the thermostat adjustment control. Turn the control to hotter if the temperature inside the oven was lower than the set temperature, or turn the control in the opposite direction if your oven was hotter than you set it. Replace the knob and retest your thermostat.
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