If your biscuits, pies or corn bread isn’t browning/cooking the way grandma used to…you may need to calibrate your oven temperature.
The first step – get a good thermometer.
You can purchase highly recommended models for less than $10.00. All dial-face thermometers work by the same internal mechanism.
A bimetallic strip (that is, two pieces of different metals pressed together) is wound into a tight coil and connected to a tiny dial. The two metals expand and contract at different rates when heated or cooled, moving the dial on the face.
As simple a mechanism as this is, quality controls clearly vary from factory to factory. I recommend the CDN ProAccurate Mechanical Thermostat.
Inspector’s Note: It is beyond most state and Inspector Association Standard of Practice to perform technical inspections and inspectors don’t dismantle equipment during the home inspection.
TO TEST THE OVEN
- First and foremost, place your thermometer in the middle of the center rack, where most food cooks. Set the oven to 350 degrees.
- Allow the oven to preheat for at least 20 minutes and take a temperature reading. This will tell you if the oven is even reaching the desired temperature from the beginning.
- To test if the oven is properly calibrated and maintaining its heat, continue to take readings every 20 minutes for the next hour and a half to two hours.
- Divide the sum of the readings by the number of readings you have taken. The average should be around the original set temperature.
Place your thermometer in the middle of the center rack, where most food cooks.Cook’s Illustrated Magazine
TO ADJUST THE OVEN (Knob Style Control)
For digital style controls consult your owners manual.
If you determine the average temperature is not correct, diagnosing the exact cause of the problem can be time-consuming. Often, the oven temperature dial simply needs to be adjusted to match the internal temperature of the oven.
- First, ensure the internal thermostat sensor on the inside of the oven is secure and not touching the inner walls.
- Next, place the oven thermometer in the center of the middle rack. Set the oven to 350˚F (176.67˚C) and let the oven heat for at least 20 minutes. Take a reading of the internal temperature and a reading every 20 minutes for the following hour and a half. Calculate the average of the readings.
- Next, remove the plastic knob from the temperature dial. It should pull off without tools. If you have trouble removing it, slide a screwdriver behind the knob and gently pry to remove it.
- Mark where the alignment flat spot (or slot) on the back of the knob is with a marker so you can reference it or come back to it if something goes awry.
- Next, use a screwdriver to loosen the screws holding the outer part of the dial to the inner mechanism.
- Calculate the difference in the set temperature and the calculated average. If your oven is not reaching the correct temperature, hold the stem and rotate the dial counter-clockwise. If the oven is running too hot, hold the stem and rotate the dial clockwise.
- Tighten the screws and reattach the knob to the dial on the oven.
- Optionally, you can test the adjustments by taking the average temperature of the oven once more and repeat the steps as necessary until the oven is reaching the desired temperature.
WHEN TO CALL APPLIANCE REPAIR
If this doesn’t fix the issue, the problem could be with a faulty heating element, thermostat sensor, or another component that needs replacing.
If this is the case, the temperature is off by more than 100˚F (37.78˚C) or the heat oscillates by more than 20˚F (-6.67˚C) above or below the set temperature, you should consider calling a professional appliance repair contractor.
Join my 8,000+ member Facebook group for homeowners and inspectors.