oven temp swing
I have a digital thermometer with a thermocouple on the end of a long, flexible cable (I roast coffee) and only recently started using this to monitor the temps in my oven. It reads instantly (most cheap thermometers take minutes to register a heat change - this is instant)
To my dismay/surprise, my oven temp has a ridiculous amount of temp swing. If I set the temp to 400F, for example, the temp will go up to nearly 500F before the element shuts off and then it cools down to about 380 before it comes back on and then swings up to 480F and back down again and so on.
My kitchen has an odd sized space for the oven (40") and I had only a few choices (most of them super expensive) and I went with an affordable Kenmore dual fuel that has convection in the larger side and a narrower side oven without convection. It was about $2K vs $10K for any other brand I could find in that size - still plenty expensive, I thought, so I would have expected better temp control.
I have ordered a 3/8" baking steel (was planning to experiment with pizza) and I may find that it will even out the temp swings.
Curious if this is normal for an oven (perhaps preheating for a longer period evens it out?) and if any of you have to deal with this - and ... well, this is silly I guess, I never really had any trouble with it. I mean I've been baking bread for years in it and only this week ever got around to sticking a thermometer in it and noticed the swing. So maybe it's just not an issue.
You may have a problem that your thermocouple probe is reading or affected by radiation heat transfer rather than just reading air temperature. Shield it and repeat your test. By shielding it I mean put something that blocks “light” from the element – a cookie sheet will work fine. I have seen this problem when using a kitchen oven to draw the temper on a tool that has been placed in a home oven for tempering. Also a problem in small toaster ovens.
If you still have the problem than the supplier should fix it. Temperature swings should be less than +/- 10 F not counting opening and closing the door.
said that 25-30+ degrees either way was normal. He was very clear that ovens do not stay at the temperature we set. The oven heats up past what we want and then cools off to below the set temp, which then triggers the elements to heat up past what we want again. Oven temps are just an average is what he told me.
At one point when my oven was giving me grief, I bought 3 oven thermometers and they all read differently. So what I learned from that is to not get too uptight about the temp as long as the oven is heated up nice and hot. Then play with settings until you are happy with your baking results.
I would expect that the baking steel (or other thermal mass, like thick stones) will even out the temperature. Mine (granite) hold the heat for many hours after I've finished baking, even being still warm the next day.
Andy, I have a similar situation with constant oven temperature, possibly. I'd like to determine what the temp fluctuations are. What model thermometer are you using? And are you sure it's accurate and reads instantaneously? Being the scientist that I am, I'd like to eliminate as many cooking variables as possible. I recently calibrated the oven temp setting (digital); it was cooking about 25 degrees too high.
That said, I started using an oven stone a few days ago, hoping that would reduce/eliminate fluctuations. But I still wonder.
Dave
There are certainly better (and more expensive) thermometers available than the one I use. It isn't quite "instant" but it registers accurately very quickly. Mine is a true Thermocouple (two different metals for the two wires that are fused together into a bead on the end of the wire (heat proof insulation). So there isn't much metal mass (just a very fine wire bead) ---- vs the cheap digital probe type thermometers that are meant to poke into meat. Those cheaper type have a thermistor (not a thermocouple) inside the metal poker - and the metal probe absorbs the heat from the meat or bread or whatever and gradually heats up the sensor inside. That makes them slower to read and also they usually read low because the metal sleeve conducts the heat away from what you're measuring.
I bought mine from Sweet Maria's (I got it for coffee roasting) and I bought several thermocouple wires from Amazon so I would have spares (they get bent up and eventually stop working).
I'll post the link but that may cause my post to be banned as spam. https://www.sweetmarias.com/product/digital-thermometer-with-thermocouple
I ordered the thermometer this morning. I had seen other similar units, but they cost several hundred $. My only question is why this thermometer will read up to 1382 degrees while the probe will survive only up to 480. Hope it will work in my oven at 450 (fluctuations notwithstanding).
One easy way to verify that my thermometer is accurate - I am at sea level and it reads 212F when I put the tip in boiling water - and ice cube bath reads 32F. I don't have any trick to verify it is accurate at 500F but I believe it is very close.
My thermocouple being so low in thermal mass and reading so quickly is probably why I see such a swing compared to people measuring with a slower reading thermometer that has more metal mass surrounding the sensor. And for baking bread - those quick swings in temp may not matter much (for coffee roasting they do, you really want a steady and constant temp curve).
Well when I was getting that link for you, that was the first time I'd ever noticed that --- but I do know you can buy a wide variety of types of probes and use with that base unit. In fact there are Volt/Ohm meters (fancy ones) that have a jack for a thermocouple and will read temps. They work by a voltage being generated by two two dissimilar metals as they get hot (vs the cheap ones use a varister that don't generate any voltage, but their resistance changes when they get hot - those are slower and less accurate).
I generally roast coffee to anywhere from 440F to 458F and the covering (insulation) starts to turn brown (probably from the coffee though) but the tip itself won't melt. I've been using it for over 5 years at least once a week. I've even put the tip directly in the flame of a propane torch and could not get it hot enough to melt. (the way they are made is by twisting the two metals together and putting them in a much hotter acetylene torch flame until the junction melts into a bead. But my propane torch couldn't generate enough heat)
So I don't really know what might happen at 550F but I suspect the probe would continue to work fine. You can search Amazon (or wherever) for replacement tips of various shapes and heat ranges you just have to make sure it's the right type to work with that base unit.
I get a quick read when I stick the probe in a loaf of bread or into hot water. Reading the air is odd (air currents? I'm not really sure why) so when I hang the probe in a hot oven - it seems to take longer to register. Or maybe it's just my oven. You'll have to let me know how it works for you. I hope you like it, I've been happy with mine.
You said: So I don't really know what might happen at 550F but I suspect the probe would continue to work fine. You can search Amazon (or wherever) for replacement tips of various shapes and heat ranges you just have to make sure it's the right type to work with that base unit.
I certainly hope the temp fluctuations in my oven don't rise to 550F with a 450 setting. I bake at 425-450F.
When the unit arrives, I'll see what's going on and report back to you. Thanks for the info. Dave
I baked two loaves of bread this evening with a 3/8" oven steel. I preheated much longer than usual - though it didn't seem like I needed to (my thermocouple probe read the temp staying pretty stable).
It made a big difference - I had very little temp swing this time with the oven temp staying very close to what I set it.
I was baking in bread pans and wasn't sure I should set the pans directly on the steel or not - so I set them on a wire rack just 1" above the steel. My thermometer read pretty consistent temps - oven set to 350F and the temp was ranging 335-355F throughout the baking time. My crust came out MUCH lighter than usual (which may be a good thing, it hasn't cooled yet so I haven't tasted it) and the loaves read 208F inside and have a hollow thump so I think they are done.
I'm guessing the darker crusts I've been getting (I've felt like it was too dark) was because of how high the temp would swing each time the heating element cycled on. I'm thinking I might try a slightly higher temp next time I bake but I'll know more when I cut into the loaf and see how it is.
Do you think I should just put the pans directly on the steel rather than wire rack above the steel? Does it matter?
I'm using a ceramic baking stone on the bottom rack to even out the temp fluctuations, whatever they are. I place my baking pan on the top rack, about 3 1/2" above the stone. Thought about placing the pan directly on the stone, but am afraid of the thermal shock from a hot stone and cool pan. I guess with steel, it doesn't matter.
I recently went to a different oven pre-heat procedure. During the warm up, I heat the oven in the convection bake mode so the fan moves air about and heats everything evenly. Then I switch to regular bake just before putting the pan in the oven. I haven't tried baking in the convection mode because that seems to require about 25F less than regular bake. Another variable to deal with and I have enough already.
I think I know about the max temp question. I was testing a pizza steel and trying to see if I could get it hotter by having it close to the broiler. It's the insulation on the probe wire that can't handle the heat - it burst into flames but I saw it the instant that happened and pulled it out. Still works fine but I'm pretty sure that's the heat limit on the probe. I was hotter than 550F when that happened.
I received the Mastech thermometer today and the probe is in the oven, set at 450F in the regular baking mode. The ceramic baking stone is on the bottom shelf. The Mastech has been reading 449-451F for the last hour, I'm happy to report. I'll give it another try tomorrow without the stone in place to see it it makes a difference. Thanks for steering me to this device.
I heated the oven this morning to 450F without the stone on the bottom shelf. The initial temp went to 515F, then settled down to 440-465. The stone certainly evens out the temp.