Author Topic: Dual oven effect when using large baking surfaces  (Read 1793 times)

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Offline JD

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Dual oven effect when using large baking surfaces
« on: September 16, 2013, 09:27:56 AM »
I'll try and make this as brief as possible:

My results on steel have been nothing like what others have posted, and I think I understand why now. I have a home oven (gas) that goes to 550. I use a steel plate that is 20"x 22", my oven interior is around 22" x 26". Therefore I have about 1" gap on each side front to back, and 2" gap on each side. Due to these relatively small gaps and the fact that my oven stays lit more often than it is off, I figured the bottom "oven" had to be hotter than the top. So I used two oven thermometers and kept rough track of it last night (see graph).

These are rough temperatures after the preheat was complete, with the oven set to 535.

So what's the point? Well if the lower oven stabilized around 575* and the upper at 535*, what would my steel plate be? Of course I don't have an IR gun, but since heat rises I'd put money that the steel is close to 575* and causing a seriously uneven baking environment. I'd also put money that this effect is less relevant in electric ovens since venting is not necessary.

For my bake last night, my undercrust started to show burn marks at 2 minutes 30 seconds. Question for Scott: Would that time make sense to you if someone was using steel at 575*?  Would you agree using steel in a gas oven may create this dual effect, and a lower temp may be recommended?

Josh


Offline TXCraig1

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Re: Dual oven effect when using large baking surfaces
« Reply #1 on: September 16, 2013, 09:51:51 AM »
How about creating the upper-lower effect using aluminum foil on a rack and then placing the steel on the bottom of the "lower" oven?
Pizza is not bread.

Offline scott123

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Re: Dual oven effect when using large baking surfaces
« Reply #2 on: September 16, 2013, 09:57:04 AM »
Josh, this is very useful data.  I've talk before about stones heating up a bit faster in the lower quadrant of an oven, but, because the thermostat is cycling the oven on and off, there's going to be an equilibrium reached, which your numbers seem to show.  Because the heat source is on the bottom and there's no deflection involved, there will always be a slight discrepancy between upper and lower temperatures, but, if given enough time to fully pre-heat, not only will the discrepancy reduce, but you should see a similar final stone/steel temp in all oven shelf positions.

Clearance plays a role- the more flow you have from bottom to top, the faster the equilibrium takes place. In a broilerless setup, I take advantage of this and put in a false ceiling with a secondary ceiling above that in an attempt to keep the heat in the bottom, but if you have a broiler in the main compartment, you don't have to worry about that.

As to your question, I don't think anything particularly special is going on here other than your oven is running a bit hot.  An IR thermometer would definitely help to answer some questions, but, until you obtain one, I'd put the steel towards the top of the oven (5" from the broiler) and pre-heat if for 60 minutes on 525 and see what kind of color you're getting at 4 minutes. If it's still too charred, go with 500.

Btw, this is a pretty good deal:

http://www.amazon.com/Etekcity-Temperature-Non-Contact-Infrared-Thermometer/dp/B00837ZGRY/?tag=pizzamaking-20

It only goes to 716, but that's fine for NY style.  I swear the 1300F model was $22 a few days ago, but now it's $25.  That's Amazon for you. If you think you might end up ever doing Neapolitan in a WFO, I'd splurge for the higher temp.

Offline scott123

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Re: Dual oven effect when using large baking surfaces
« Reply #3 on: September 16, 2013, 09:58:36 AM »
How about creating the upper-lower effect using aluminum foil on a rack and then placing the steel on the bottom of the "lower" oven?

Josh has an issue with his steel getting too hot and charring his undercrust too quickly.  If he isolates the steel with a false ceiling, he'll drive the temp up even higher.

Offline mbrulato

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Re: Dual oven effect when using large baking surfaces
« Reply #4 on: September 16, 2013, 10:26:34 AM »

Btw, this is a pretty good deal:

http://www.amazon.com/Etekcity-Temperature-Non-Contact-Infrared-Thermometer/dp/B00837ZGRY/?tag=pizzamaking-20

It only goes to 716, but that's fine for NY style.  I swear the 1300F model was $22 a few days ago, but now it's $25.  That's Amazon for you. If you think you might end up ever doing Neapolitan in a WFO, I'd splurge for the higher temp.


Scott,

You are correct, it was cheaper a few days ago when I first looked at it.  I ordered it anyhow, just in case there is ever a need for me to track temp of a WFO 😝

Mary Ann
Mary Ann

Offline JD

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Re: Dual oven effect when using large baking surfaces
« Reply #5 on: September 16, 2013, 10:50:04 AM »

As to your question, I don't think anything particularly special is going on here other than your oven is running a bit hot.  An IR thermometer would definitely help to answer some questions, but, until you obtain one, I'd put the steel towards the top of the oven (5" from the broiler) and pre-heat if for 60 minutes on 525 and see what kind of color you're getting at 4 minutes. If it's still too charred, go with 500.



I agree I need an IR, but let me throw you a counter argument first.

1) I keep the steel on the second shelf from the top, which is probably 6 or so inches from the broiler. I've done various temps, and even at 500 I was starting to char at 3-3.5 minutes.

2) The thermostat is in the upper oven, not the lower. You can see once it reached equilibrium, the upper oven was 535* (which is what my oven was set to). Therefore I think my oven is pretty accurate, and the reason the lower oven is hotter is because to maintain 535* up top, the lower section needs to be around 575 due to the amount of heat escaping since it is a gas oven and needs to be vented. This is equilibrium for my setup, does that make sense?

Are electric ovens vented like gas ovens so you would get the same amount of heat loss regardless of the type?  My hunch says no, gas has to be vented, electric doesn't as far as I know.

Josh

Offline scott123

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Re: Dual oven effect when using large baking surfaces
« Reply #6 on: September 16, 2013, 11:13:53 AM »
Josh, I'll tell you what, spend the 15 bucks (plus filler for free shipping), get the IR thermometer and then we'll argue the finer points of electric vs. gas oven heat imbalance/retention. Deal?  >:D

Semi-seriously, though, if 500 is giving you too much char with the plate on an upper shelf, go with 475.  It's not at all unheard of for ovens to run 75 degrees hotter than the dials.

Offline JD

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Re: Dual oven effect when using large baking surfaces
« Reply #7 on: September 16, 2013, 11:24:58 AM »
Josh, I'll tell you what, spend the 15 bucks (plus filler for free shipping), get the IR thermometer and then we'll argue the finer points of electric vs. gas oven heat imbalance/retention. Deal?  >:D

Oh I just assumed you already knew and were willing to share, Scott  >:D


It's not at all unheard of for ovens to run 75 degrees hotter than the dials.

I can keep arguing this point, but I think we're at a stalemate here...
Josh

Offline TXCraig1

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Re: Dual oven effect when using large baking surfaces
« Reply #8 on: September 16, 2013, 12:05:56 PM »
Josh has an issue with his steel getting too hot and charring his undercrust too quickly.  If he isolates the steel with a false ceiling, he'll drive the temp up even higher.

But he'd be putting 50F or maybe more higher temp above the pie, right - so he could bake for a shorter time, right? Mhat I was trying to suggest is a way to reduce the heat imbalance, and he can always lower the oven temp.
Pizza is not bread.

Offline scott123

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Re: Dual oven effect when using large baking surfaces
« Reply #9 on: September 16, 2013, 12:19:22 PM »
But he'd be putting 50F or maybe more higher temp above the pie, right - so he could bake for a shorter time, right? Mhat I was trying to suggest is a way to reduce the heat imbalance, and he can always lower the oven temp.

The moment you add a false ceiling, regardless of the material of the ceiling, it's a broilerless setup and it's imbalance city.  The hotter you take the lower area, the hotter the steel gets, the worse the imbalance.  If you want to go broilerless, then it's about less conductive hearths and/or deflectors underneath the hearth- which may not be the worst idea if JD is truly dead set against using his broiler. But steel, on it's own, without a top heat source, is a no go.


Offline scott123

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Re: Dual oven effect when using large baking surfaces
« Reply #10 on: September 16, 2013, 12:23:39 PM »
I can keep arguing this point, but I think we're at a stalemate here...


Oh, come on, Josh  ;D I didn't say anything at the time, but this is pretty damn stunning

http://www.pizzamaking.com/forum/index.php/topic,26901.msg276397.html#msg276397

If you dial down the crispiness, you've got a world class pie. If you use the broiler, you'll dial that crispiness down, trust me.  Just get those fingers moving.  I know using the broiler sucks, but suffer a little for your art  :-D You're so close!  ;D

Edit:  using that pizza as a guide, with a 500 pre-heat, you should be able to turn the broiler on at the 1:30 mark and have the right top and bottom color at 4:00.
« Last Edit: September 16, 2013, 12:25:45 PM by scott123 »

Offline JD

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Re: Dual oven effect when using large baking surfaces
« Reply #11 on: September 16, 2013, 12:41:07 PM »
Oh, come on, Josh  ;D I didn't say anything at the time, but this is pretty damn stunning

http://www.pizzamaking.com/forum/index.php/topic,26901.msg276397.html#msg276397

If you dial down the crispiness, you've got a world class pie. If you use the broiler, you'll dial that crispiness down, trust me.  Just get those fingers moving.  I know using the broiler sucks, but suffer a little for your art  :-D You're so close!  ;D

Edit:  using that pizza as a guide, with a 500 pre-heat, you should be able to turn the broiler on at the 1:30 mark and have the right top and bottom color at 4:00.


I completely agree a broiler is the best option still. When I first learned of your 4 minute bake on steel, I was very excited to say the least. But my results were nothing like what I thought I would get. I always thought it was because we just had different tastes, but after Mary posted her beautiful first attempt and you said that was typical, it got the wheels turning.


The point we're disagreeing over is whether my oven is running hot or not. I think it's not, I believe it's due to the higher temperature in the lower half of the oven. That's all I'm saying.

When you recommend to make the steel dimensions really tight, I'm curious if it is actually counter-productive in a gas oven due to the venting issues.
Josh

Offline scott123

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Re: Dual oven effect when using large baking surfaces
« Reply #12 on: September 16, 2013, 12:52:18 PM »
The point we're disagreeing over is whether my oven is running hot or not. I think it's not, I believe it's due to the higher temperature in the lower half of the oven. That's all I'm saying.

When you recommend to make the steel dimensions really tight, I'm curious if it is actually counter-productive in a gas oven due to the venting issues.

Well, if you really want my opinion on the subject  ;D then there probably is a greater difference in temperature in a gas oven than an electric one, but if the plate gets too hot, you can always pre-heat to a lower temperature.

If you look at the slots where the heat is coming up from the bottom of a gas oven, it's not a lot of area.  And if you look at the top of the oven, the vent isn't all that large either.  Most people get more than an inch clearance on the sides of the plates, but I think, based on the vent surface area and the surface area of the holes on the floor, I think an inch on both sides is plenty.

Once you invest in a high temp thermometer  ;) you'll check the floor temp and it will be considerably higher than everything else. When you put a piece of steel in, you're basically creating a second floor, so the plate will be hotter than the ceiling above it- hotter than the thermostat.
« Last Edit: September 16, 2013, 01:01:14 PM by scott123 »

Offline mbrulato

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Re: Dual oven effect when using large baking surfaces
« Reply #13 on: September 16, 2013, 12:58:11 PM »
Josh, FWIW, only one of my four pies looked great.  i did not post pics of the other three.  I noticed that my preheat with steel plate in the oven seemed to take a bit longer than normal.  I'm not sure if it had anything to do with the steel sitting up within an 1/8 of an inch of the back wall where the fan is or it is just coincidence.  When you say tight measurements, for my oven the steel had 1/8" in front and in back of space between it and the wall/door. And it had 3 inches of space between it and each side wall.  My oven is electric.  Don't know if this information is helpful to you or not, but I hope so. Did you order the IR thermometer? I think it will be very helpful  :)

Mary Ann
Mary Ann

Offline JD

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Re: Dual oven effect when using large baking surfaces
« Reply #14 on: September 16, 2013, 01:16:44 PM »
Well, if you really want my opinion on the subject  ;D then there probably is a greater difference in temperature in a gas oven than an electric one, but if the plate gets too hot, you can always pre-heat to a lower temperature.

If you look at the slots where the heat is coming up from the bottom of a gas oven, it's not a lot of area.  And if you look at the top of the oven, the vent isn't all that large either.  Most people get more than inch clearance on the sides of the plates, but I think, based on the vent surface area and the surface area of the holes on the floor, I think an inch on both sides is plenty.

Once you invest in a high temp thermometer  ;) you'll check the floor temp and it will be considerably higher than everything else. When you put a piece of steel in, you're basically creating a second floor, so the plate will be hotter than the ceiling above it- hotter than the thermostat.

I acknowledge your response ;D, and of course I want everyone's opinion, you can't learn if you're always right.   


Josh, FWIW, only one of my four pies looked great.  i did not post pics of the other three.  I noticed that my preheat with steel plate in the oven seemed to take a bit longer than normal.  I'm not sure if it had anything to do with the steel sitting up within an 1/8 of an inch of the back wall where the fan is or it is just coincidence.  When you say tight measurements, for my oven the steel had 1/8" in front and in back of space between it and the wall/door. And it had 3 inches of space between it and each side wall.  My oven is electric.  Don't know if this information is helpful to you or not, but I hope so. Did you order the IR thermometer? I think it will be very helpful  :)

Mary Ann


Thanks for the info Mary Ann. Do you have two "regular" oven thermometers and a glass oven door? I'd be very curious to know if you get the same dual zone effect I do. With an electric source and convection, I'd bet your oven is much more even than mine is.

Josh

Offline mbrulato

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Re: Dual oven effect when using large baking surfaces
« Reply #15 on: September 16, 2013, 01:24:50 PM »
Josh,

I do have glass doors on both my ovens, but I do not have any regular oven thermometers.  My IR is coming tomorrow, so I will keep track of the readings between each pie, pre heat temp, temp of steel after an hour at 550 on convection, and after about 5 minutes of broiler before I launch the first pie.  If you would like any other temps or information, just let me know and I'll write them down. I love helping  ;D

My next bake is on Friday dinner time so I'll post some info/pics afterwards on the thread I started last Friday.  I used to be an auditor, so documentation is up my alley  :-X

Mary Ann
Mary Ann

Offline JD

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Re: Dual oven effect when using large baking surfaces
« Reply #16 on: September 16, 2013, 01:40:28 PM »
Thanks Mary Ann. My curiosity is in the air temps, but I suppose after an hour the back oven wall temp should be about the same as the air. I would be curious to know the back wall temps of the upper and lower section of your oven, after the full preheat is complete. If you can, could you take a reading 2-4" below the steel plate, and 2-4" below the ceiling of your oven?

If your glass is clean you should be able to take readings with the door closed, which would be easy for you.

If your upper and lower sections are in fact different, take a reading of the steel too. This would be good info for me I think, but I really believe your oven will not vary much, especially if you use convection.
Josh

Offline scott123

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Re: Dual oven effect when using large baking surfaces
« Reply #17 on: September 16, 2013, 01:45:34 PM »
This would be good info for me I think, but I really believe your oven will not vary much, especially if you use convection.

Yes, an electric oven will mitigate the phenomenon you're seeing and convection will eradicate it completely. As far as I've seen, as long as the fan is running and not blocked, there's no spot in a convection oven that's hotter than another.
« Last Edit: September 16, 2013, 01:51:53 PM by scott123 »

Offline JD

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Re: Dual oven effect when using large baking surfaces
« Reply #18 on: September 16, 2013, 02:07:09 PM »
Yes, an electric oven will mitigate the phenomenon you're seeing and convection will eradicate it completely. As far as I've seen, as long as the fan is running and not blocked, there's no spot in a convection oven that's hotter than another.

... I'm a bit confused, I think you and I are in agreement on this issue but just speaking two different languages.


Actually now that I think about it, the more useful data would be to leave convection off and take the readings to see if a standard electric oven shows the same phenomenon that a standard gas oven does. I don't want to jeopardize your pizza night though so don't do anything you are not comfortable doing Mary Ann.





Josh

Offline shuboyje

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Re: Dual oven effect when using large baking surfaces
« Reply #19 on: September 16, 2013, 06:39:38 PM »
There must be some history I'm missing here, because I don't see what the issue is.  It makes sense that the bottom of the oven will be hotter with the bottom burner running with your setup as mentioned.  When it's time to cook you turn off the bottom burner and crank up the broiler, you'll never get a balanced high speed bake in a home oven without the broiler providing top heat.  That makes this a non issue.  The bottom temperature will drop pretty quickly and at this point the plate will be transferring heat to the bottom of the oven, not vice versa. 
-Jeff


 

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