HBL8651UC/01 Bosch Double Oven - Excessive Temperature Fluctuation

syspig

Premium Member
Joined
Aug 21, 2018
Messages
2
Location
PNW
Model Number
HBL8651UC/01
Brand
Bosch
Age
1-5 years
Greetings, all. Problems with a Bosch Double Oven, model HBL8651UC/01.

Out of warranty, about 2 years old. Since day one, my wife has suggested the temps seem inconsistent. Admittedly, I didn't take it very seriously and assumed it was just a matter of getting used to a new oven. We don't bake a lot.

We've a visitor staying with us who loves to bake, and immediately noticed the same thing. We've done some testing, and there does indeed appear to be an issue.

Armed with a ThermoWorks Oven Probe, we tested both the upper and lower ovens and had essentially the same results in both.

- Pre-heat to 350 worked as expected, taking the temps up to 365 before cycling off

- Both ovens drop clear to 295-300 before cycling on, again shutting off at 365

I called the only Bosch service within 100 miles, and they couldn't even advise if the above behavior was normal or not. They told me to call Bosch.

I did so, and they basically said it sounds off - but only a service technician would know for sure. They referred me back to the Bosch service center that couldn't advise if a problem exists or not.

I've skills to dig into this myself with a little guidance, but before considering that - can anyone confirm that this is indeed, excessive temperature swing? And if so, what a short list of possible fixes might be?

Thanks much.
 

Jake

Appliance Tech - Admin
Staff member
Joined
Aug 24, 2004
Messages
100,713
Location
McMullen Valley, Arizona
Hi,

Here's the owners manual for your model: https://drive.google.com/open?id=1LseIDyS6S7NgvJzTXHBe06Z_CqfO7-wl

Look at Page 17 Where it says Temperature Offset.

What the oven should do is preheat the average temperature of 350 degrees. So you should see it go to about 375 degrees, then drop down to about 325 degrees before it cycles on again, so the average is 350 degrees.

It looks like you need to raise it 10 degrees on that temperature offset setting.

Jake
 

syspig

Premium Member
Joined
Aug 21, 2018
Messages
2
Location
PNW
Thanks, Jake.

After playing around with those settings a bit, it became clear the offset numbers represent something other than degrees Farenheit in my case. Pushing it up 10 degrees took it to nearly 400 (365 previously) before it turned off the element, and it cycled back on around 344. Regardless, after several cycles and testing various offsets I've got the average temps where they should be when set at 350.

However, the variation still seems a bit extreme. After several cycles, it settled in to a pretty steady 60 degree range - on at about 320, off around 380. Same for both upper and lower ovens.
 

Jake

Appliance Tech - Admin
Staff member
Joined
Aug 24, 2004
Messages
100,713
Location
McMullen Valley, Arizona
I don't know what else to suggest, sorry.

If this happening on both ovens then it can't be the oven sensor, as each oven has its own oven sensor, and the chances of both oven sensors going bad at the same time is highly unlikely.

That's probably the closest you will get it unfortunately. Unless Bosch has a service bulletin on this problem, but you'd need to have a authorized Bosch tech come out to see.

Jake
 
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