When you turn on your oven to bake those cookies your have lovingly made with the little time you have in your day, the last thing you want is for them to burn or be under baked. I hope the information on how long I should preheat my oven will be helpful in your quest for the perfectly browned roast or perfectly baked loaf of bread.
After 23 years in the appliance repair business I have learned a lot, in terms of the little secrets about your appliances, that can dramatically affect the outcome of your recipe. So the question is; “How long should I preheat my oven?”
First the basics: Do you know if your temperature is accurate? You will need a 
GOOD digital thermometer The cheap one from the dollar store is only going to confuse things because they can be highly inaccurate.
Turn your oven to a set temperature and give it a good 20 minutes to come to temperature. The oven is going to fluctuate up and down after it comes to temp. It will cycle between 20 and 30 degrees up and down while it cycles. This is normal, so do not be alarmed.
If you don’t have a good thermometer, just bake a cake! It should come out within a few minutes of the time listed on the box. But be sure to use the correct pan, preheat your oven fully and bake it for the time listed on the box. A bigger or smaller pan is going to affect the cooking time. And there is more to this. Read on to “Preheating Your Oven,” before you do the cake test.
Preheating Your Oven: How long should I preheat my oven? When you preheat your oven, the little dinger will go off after about 10 minutes. Disregard the dinger! Do not put your food in just yet. That initial dinger is telling you that the air inside the cavity is to a certain temp. However, those cold walls INSIDE the oven have not quite absorbed all the heat. What that means is that if you put your cookies in after the first ding, the oven will not hold that initial temperature very long, and it will cycle back on to bring the temperature back up. That throws your cooking time all off, and it may cause uneven baking. So let your oven heat at least 20 minutes to fully bring the ENTIRE oven to its correct temperature before you put your food in.
Don’t Peek! Every time you open the oven you lose approximately 50 degrees of heat, so use your oven light and trust your recipe. And if you must open the oven, be ready; have your next batch by your side and be ready to take the first batch out and the next one in as fast as you can. No opening the door, walking across the kitchen, then back to the oven. That will totally mess with your cooking time and final outcome of the recipe!
Now, if you find out that the temperature IS off, what do you do? First, make sure there are no foil liners on the bottom of the oven. I know. I know. They help keep it clean. However, if your oven is gas, it will block the air/gas mixture and ignition process, which can cause a delayed ignition and can cause a gas build up with a mini BOOM when it does ignite. Not good. If your oven is electric, the foil can short out the element or thermostat. So, in a nutshell, get rid of the aluminum foil!
After that, all I can tell you is call a reputable service company. Use the BBB, Angie’s List, referral from friends, but be careful whom you choose to do your service. Ask questions. Establish exactly how much it will cost to send a technician to your home and get an estimate. DO NOT expect that if they do not tell you their service call charge that it is free. ASK! ALL reputable service companies that come to your home have to charge to bring the company to your door. Make sure they are established and do factory service for your brand. They are much more knowledgeable than “the other guys.” They might cost you a little more, but you get what you pay for. And you do not want a ding-dong in your home who hasn’t a clue how to work on your appliance!
So preheat your oven correctly and your cooking/baking/broiling results will be much better! Happy Cooking, readers!
