Oven temperature fluctuations - how can this be?

8 years ago

Hi, we installed a new oven last month and it doesn't seem to be working properly. The temperature is fluctuating wildly. We first noted that frozen pizza was not cooking right (same pizza we've been cooking for three years, once a week, in three different ovens over the past two years). Banana bread and cookies took longer (by a lot) in the new oven.

Decided to try a cake mix today: preheat to 350. Put in batter (door open no more than 5 seconds) and temp dropped interfaith reaching 265 at 11 minutes. At 19 minutes the temp rose to 350, then 367 at 22 minutes. It dropped back to 340 at 26 minutes. At 26 minutes, I opened the oven and very quickly tested the cake. The temp dropped to 309, them rose to 317, then started to drop again. Tested again at 29 minutes, removed the cake, temp dropped to 269 after removal.

The cake was cooked. Bizarre when the temp was well below the set temp for most of the cooking time.

1. How can this be?

2. Do the temp movements seem normal?

We've tested the oven using two manual and one digital thermometers. We had similar fluctuations with the pizza cooking at 400 - it did not cook properly.

The oven tech insists the oven is okay. His probe registered the temp at 350 and it maintained that temp - he said. We'll ask him to test again tomorrow and watch the probe.

Any thoughts or suggestions would be appreciated. It's a Bosch series 800 wall oven.

Thanks.

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Comments (4)

wekick
8 years ago
I would keep a written log of temp readings and times for this test and while cooking. This is a little time consuming and might require more patience than your repair tech has but when they come to test the oven, bring it to 250F and watch the variation in temperature. You should be able to see the upper and lower temperature. Bring it to 350F and watch the variation. Open the door for 10 or even 15 seconds and then note how much the temperature drops and how quickly it recovers. It would be normal to drop at least 50-100F degrees when you open the door. When it recovers, bring it to 450F and observe it.

The generally acceptable variation in temperature from the set temperature is considered to be 25F, so if set at 350F, it will be between 325F and 375F. Many newer ovens have a much lower variation so ask them what it should be for your oven before you start your test. My oven after it is well preheated takes about 60 seconds to come up 50F. Note how long it takes to change temperature.

Did you use all three of your thermometers at once and did they agree with each other? Thermometers have lag time after the oven changes temperature. You might use yours along with the tech's for comparison.

One thing that will help stabilize your oven is to have it well preheated. When the oven preheats to 350F and turns off, it needs to run additional time so that the sides and bulk of the oven fully heat.

I am curious if your previous ovens had open elements on the bottom as the covered elements can cause things to bake differently.
homepro01
8 years ago
I do agree with Wekick. Hidden element ovens do take longer to preheat and the preheat beep really means nothing. Are you using thermometers that you keep in the oven during use?

One option is: Can you return the Oven? Have you contacted the place you purchased the appliance from? I am not sure that as a user, you should be struggling to understand if the oven was working correctly.
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rococogurl
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No idea if it's the case with the oven you have, but I would ask about temperature averaging. I had a Viking wall oven that did that and it was terrible. Wild fluctuations and things did not cook properly. If that's the case I would see if a buy back is possible.

However, it is important to preheat a 30" wall oven for 30 minutes. Ding or no ding, that's how long it takes. After that, if it does a boxed cake mix in the set time and the cake is done, it is likely OK.

When you open an oven door, you lose about 30% of the heat in the oven. Some ovens go back to temperature quickly while others do not.

Using a thermometer can be counterproductive since these are not like the old ovens without electronic sensors.
cmw829
Original Author
8 years ago
Thank you for the replies. We used all three thermometers at the same time. Of course, the manual ones didn't respond as quickly as the digital. We cooked another pizza last night and I told my husband to just let it cook without fooling with the temp. If it was undercooked, so be it. If burned, same. It was perfect. We also waited an additional ten minutes after the preheat beep to put it in.

Tech was here again today to replace one of the refrigerator doors and put his probe in again and this time we watched it. It did not have the fluctuations that our digital did and when we opened the door, his dropped slightly. Ours plummeted. Despite ours being top rated and using the optional oven probe intended to measure oven temp, we believe his to be accurate. (Unless there's a conspiracy out there to reduce service repairs.) Given that both the cake and pizza cooked properly, we are going to move forward and just keep an eye on things.

Thanks again for your input.

Oven temperature fluctuations - how can this be?

Comments (4)

wekick

homepro01

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Oven temperature fluctuations - how can this be?

Comments (4)

wekick

homepro01

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rococogurl

cmw829Original Author

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