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Offline avidan

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Building an oven with ultimate control
« on: January 19, 2012, 08:49:39 PM »
Hey all,
I am a long time reader, and avid pizza maker. I started out with a simple self cleaning oven hack, moved to an LBE, and now a full blown wood fired oven. I love making pizza, but I am also a technology control geek at heart. As an engineer, I always am excited for pursuing perfection through computer based control. (I put a PID controller on everything that will take one, my espresso machine, smoker, sous vide, the works).
I know that pizza is an art, and many will take offense to the fact I am trying to build a highly controlled oven, but for those people, i simply ask, please look away.
So, here is what I am trying to do.

I have been working on a design of a wood burning oven with a supplement of either gas or electric with a highly controllable temperature system. The idea is to have the floor of the oven PID controlled so I can set it to 800 (or any other temperature). In addition, I am looking to control the oven air temperature with variable control. For example, I would like to start the pizza "cycle" with a 800 floor/ 1400 air temp. This will last about 10-15 seconds, then i will go 800/1200 degrees for the last 75 seconds (these numbers are just pulled out of the air, if anyone has specific numbers, please share).

In order to make the fire run at such high heat, we have been looking at running a forced air system connected to a centrifugal blower, run by an arduino controller. This forced air system should be able to make the wood fire burn within a much higher range of temperatures. I know that traditionalists are against this, but we are looking at implementing a gas powered or electric coil system (similar to a ceramic kiln) underneath the floor of the cooking base. This cooking floor heating element will be independently controlled by another arduino/pid.

We are looking to make all heating elements reside OUTSIDE of the main cooking chamber. The chamber should be pure heat. We have thought about keeping all the heating elements below the oven. The wood/air burners will be offset from center, and the gas or electric heaters in the center.

I have a friend of mine currently working up a 3d model of our rough plan design, so I will post this shortly.

That being said, I am looking at several designs, and have the resources to make this happen....but, before I begin, I wanted the insight of the pizzamaking.com community.

All insight is very much appreciated.


Offline Bill/SFNM

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Re: Building an oven with ultimate control
« Reply #1 on: January 19, 2012, 09:13:04 PM »
Welcome, Avidan.

I also have my share of temperature control devices - in my proofing chamber, sous vide cooker, and BBQ pit. But I'm not sure I see the point of going that route in the WFO. You may find the environment is too chaotic and unstable with the pie being hit by different sources of heat from every angle. A proper WFO floor has high thermal mass, takes a long time to get up to temp, and should maintain a fairly constant temp if the fire is properly controlled. The radiant heat from the fire and coals is far more important in cooking the sides and top of the pie than the air temp. How do you intend to measure radiant heat hitting different parts of the pie? And how will you keep it in the desired range? By time the blowers kick in, the pizza may have blown through the very small window for a perfectly-baked pie  - maybe only be a few seconds. This process is far more about finesse and balance than it is about control. The name of the game IMO is to learn to anticipate and react to factors you will never be able to control.

Offline Bill/SFNM

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Re: Building an oven with ultimate control
« Reply #2 on: January 19, 2012, 09:20:19 PM »
I just reread your post and think I misunderstood - are you saying there is no fire at all within the cooking chamber? If so, some (much) of what I said may not be valid, but my feelings about finesse vs. control still apply, IMO. Sorry for the confusion.

Offline avidan

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Re: Building an oven with ultimate control
« Reply #3 on: January 19, 2012, 09:27:38 PM »
thanks for the reply.

yes, you are correct, there will be no direct fire in the cooking chamber at all.
I do agree that some finesse and balance still apply (this is not going to be an unmanned/automated pizza oven)....rather, this is about utilizing modern technology to get close the perfect pie. i know that there are a TON of elements that go into making this perfect pie, but hopefully a different oven design can help us get there.

now, to answer a few of your other questions.

the measurement of the temperature hitting the sections of the pie was intended to be accomplished through a series of thermocouples embedded into the floor.
the idea here is less about absolute control, but recreating the finesse and balance through some forms of computer control. for example, the idea of blasting the extra heat at the initial start is similar to the wood sawdust move done by anthony at una pizza neapolitana.
in addition, i believe we can maintain a consistent 800 on the floor similar to what the thermal mass offers.
my oven drops about 5-10 degrees on each pie i make in the same spot. so, i need to keep rotating pies. if i used a PID technique, that section would continuously stay at 800. no need to rely on the thermal mass.

i absolutely understand that this is not how pizza has been done, and hundreds of years of tradition are not anything to disregard, but if you had the budget and the goal was to implement more automated control of a wood fire oven, what approach would you take?

or more simply, how would you turn pizza cooking on its head?

Offline Bill/SFNM

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Re: Building an oven with ultimate control
« Reply #4 on: January 19, 2012, 09:44:23 PM »
Avidan,

As part of your prep for this project, you might want to study the oven created by forum member pftaylor, who now runs a very successful pizzeria in Tampa. After a great deal of research, he went the CAD route using modern materials in an attempt to improve on the traditional design. His objective wasn't control; it was about all about making the best pizza possible. Still, something you might want to take a look at.

Good luck!
 

 

Offline avidan

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Re: Building an oven with ultimate control
« Reply #5 on: January 19, 2012, 09:49:37 PM »
perfect. i will look at pftaylor's post.
thank you.
(and of course, we are trying to make a perfect pizza as well  ;D )

Offline c0mpl3x

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Re: Building an oven with ultimate control
« Reply #6 on: January 20, 2012, 04:01:01 AM »
perfect. i will look at pftaylor's post.
thank you.
(and of course, we are trying to make a perfect pizza as well  ;D )

looking at a heat treating oven may give you some better clues and design flaws towards your goals.   they are designed to hold temps in excess of 2000º+ or down to boiling temperatures within a few degrees, and are almost always electronic.
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Offline Jet_deck

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Re: Building an oven with ultimate control
« Reply #7 on: January 20, 2012, 09:36:31 AM »
.... for example, the idea of blasting the extra heat at the initial start is similar to the wood sawdust move done by anthony at una pizza neapolitana....

..... This forced air system should be able to make the wood fire burn within a much higher range of temperatures.


I see the PID controller turning the pizza to ashes by trying to regulate the oven temperatures and overusing fuel. 
... Just my $.02
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Offline shuboyje

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Re: Building an oven with ultimate control
« Reply #8 on: January 20, 2012, 09:47:10 AM »
Personally if this is what you are after I would take wood out of the equation.  I don't think the pid will be able to keep up with the constantly changing conditions of the fire, leading to less accuracy then you expect.  I would personally build a customs electric deck oven.  An element under the deck could be pid controlled to give you accurate deck temperatures.  I'd then use a element in the "dome" controlled manually by a triac to dial in the top heat.  Finally I'd use a third infrared element mounted to one side and again manually controlled by a triac to simulate the pile of coals.  This way you set the deck temp and dial in the other two elements through trial and error based on the bake time your after.
-Jeff

Offline TXCraig1

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Re: Building an oven with ultimate control
« Reply #9 on: January 20, 2012, 10:46:55 AM »
I can certainly see the allure in this. It does make me cringe a little however. Neapolitan pizza (given the temps you discuss, I assume that is your goal?) is an art first and foremost. I believe the random yet somewhat controllable nature of fire is an element necessary to achieve a “perfect” pie – if that is possible. As Bill noted, finesse is one of the indispensable ingredients.

A very wise man who I respect very much said to me just the other day, and I paraphrase, that 'pizza is a reflection of the character who makes it' (I hope I properly captured the sentiment). I had not thought about this before, but he is exactly right. I can’t help but wonder if the more we automate the process, the less character would shine through to the pie and how much we would lose because of this? My gut feeling is that it would be a lot.
 
All this being said, I’m excited to watch your build (please post lots of pics) and to see the pies you bake!

Craig
Pizza is not bread.


Offline avidan

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Re: Building an oven with ultimate control
« Reply #10 on: January 20, 2012, 12:28:08 PM »
all this feedback is fantastic, thank you!
i do appreciate the art/expression of neapolitan pizza, and that the artisan standing in front of the oven is as important, if not more important than any ingredient or piece of equipment....but, as an engineer, i have yet to program a controller for humans ;)
the reason i feel that the oven i have described is possible is mostly due to some previous builds I've done. i guess i probably should have given this background earlier. i am a professional glassblower by occupation (amongst other things, check avidanross.com) and i have been responsible for the construction and maintenance of several glass furnaces. these furnaces usually run at 2200+ F. The temperature control we have been able to attain with proper PID programming has been quite amazing. The fluctuation of the oven usually ranges in the 10's of degrees throughout the furnace. That being said, the furnace was always controlled by fuels other than wood. Our last 2 furnaces have been either entirely electric or a gas/oxy combo.
So, I hear the comments that wood fire may not be able to be controlled as easily as a fuel such as gas or electric. Perhaps I am missing something then. With exact temperatures being equal, what is the qualitative difference between these fuel sources.
I have a feeling that I am opening a serious argument that has been discussed before, so feel free to throw out some links of the arguments previously...though i guess much of the arguments will be on the abilities of these other fuels to hit 900.
that being said, i would truly like to get wood fire controlled to a level of fuels such as gas or electric...so i will keep trucking along with the design....but i do appreciate all that has been said about the art of neapolitan pizza.
i promise to employ as much art education i have learned from this forum in my pizza making :)

Offline shuboyje

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Re: Building an oven with ultimate control
« Reply #11 on: January 20, 2012, 04:39:20 PM »
With gas or electric heat you have a very predictable system.  Flip the switch today and your element is gonna put out the same amount of heat it did yesterday.  Open the valve today and your burner is gonna produce the same amount of heat as it did yesterday.  A wood fire isn't like this, there are a huge amount of variable that are constantly changing like moisture content, energy density, amount of fuel and even the shape of the fire.  My understanding of PID's is that they need to be tuned to the system to work well and they generally autotune by turning the system off and on to measure the change it creates.  This works great with a constant system and a constant heat source, but I doubt it would work well with a constantly changing wood fire.  On top of that a gas burner stops making heat when the valve closes, and an electric element stops making heat the second the contact opens.  A wood fire will continue to burn and create heat when the blower isn't running and again I think this will lead to major issues for the PID where accuracy is concerned.

I hope this all comes across as constructive.  Pizza ovens are a major passion for me, and although I generally go the traditional route, I do throw ideas like this around in my head a lot for a smaller one pizza/ portable oven as opposed to the 63" diameter 3000 pound rolling beast I have in my backyard.  If I wanted precise temperature control on a "set it and forget it" type oven I would personally go the route I mentioned above.  The beautiful simplicity of a wood fired oven is going to be lost in what you are proposing, and at that point dealing with wood and all it's downsides is just a hassle.
-Jeff

Offline scott123

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Re: Building an oven with ultimate control
« Reply #12 on: January 20, 2012, 04:55:38 PM »
I agree with Jeff. If precision is your goal, then nothing beats electric. Avidan, you've already built an electric glass furnace, so that knowledge and experience should serve you well in your quest to build an electric pizza 'forge.'

Speaking of kilns... you probably should take a look at these guys

http://slice.seriouseats.com/archives/2011/09/wild-rise-jay-street-bar-pizza-dumbo-brooklyn-nyc.html
http://www.pizzamaking.com/forum/index.php/topic,15696.0.html

I think this particular raku kiln setup has a few flaws, but it's still a good start for kiln pizza.

Offline TXCraig1

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Re: Building an oven with ultimate control
« Reply #13 on: January 20, 2012, 04:56:55 PM »
So, I hear the comments that wood fire may not be able to be controlled as easily as a fuel such as gas or electric.
I think variable nature of a wood fire is an important part of the art and necessary to make the best pie. Even heat is good. Perfectly even heat (IMHO) is not, as counterintuitive as that may seem. Consider the crust and the toppings, variability in both require finesse and adjustment in the oven. Even if you can create a perfectly controlled oven environment, you can’t create a crust without variation – there will always be thicker and thinner parts and areas with more and less gas. The selection and arrangement of the toppings change the way the pie cooks.  If you have perfectly even heat, you have nothing to adjust.

Quote
Perhaps I am missing something then. With exact temperatures being equal, what is the qualitative difference between these fuel sources.
Humidity in the oven comes to mind with electric being the lowest and gas being the highest. Radiant heat is another with wood being the highest and gas the lowest (assuming the electrical coils have exposure to the pie).

Quote
I have a feeling that I am opening a serious argument that has been discussed before, so feel free to throw out some links of the arguments previously...though i guess much of the arguments will be on the abilities of these other fuels to hit 900.
I doubt that will be a problem.

I think it is an interesting idea and worth pursuing. If it works, I think you will have an overn that will allow a less skilled person to make a pie that is better than they otherwise could but at the cost of being able to make a truly great pie.

I look forward to watching your progress.

CL
Pizza is not bread.

Offline scott123

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Re: Building an oven with ultimate control
« Reply #14 on: January 20, 2012, 05:04:17 PM »
I think variable nature of a wood fire is an important part of the art and necessary to make the best pie. Even heat is good. Perfectly even heat (IMHO) is not, as counterintuitive as that may seem.


Respectfully, I disagree  :) Below, exhibit A. (from the Nearlypolitan thread)- a 'truly great pie' made with perfectly even, electrical heat.

Pizza doesn't discriminate where the heat comes from. IR from burning wood is the same as IR from an electric broiler.
« Last Edit: January 20, 2012, 05:08:48 PM by scott123 »

Offline TXCraig1

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Re: Building an oven with ultimate control
« Reply #15 on: January 20, 2012, 06:01:28 PM »
Respectfully, I disagree  :)
Not the first time and not the last  ;D

Quote
Below, exhibit A. (from the Nearlypolitan thread)- a 'truly great pie' made with perfectly even, electrical heat.

Toby was making some incredible pies – no doubt about that. I remember exactly how blown away I was when he first posted that picture. He had great skills and passion however which can make up for a lot of oven shortcomings. I’ve yet to see anyone, except Chau maybe, match his best results despite A LOT of attempts. I think you’d also agree that you’d need to see more than the 6 or so pictures he posted to know if there was a measure of consistency in the results of relying on even heat. Did he ever say what his bake time was?

Quote
Pizza doesn't discriminate where the heat comes from.
I can’t say I’ve ever had a good Neo pie out of a gas fired brick-type oven – not that that necessarily means gas cannot be an effective heat source. I also just looked at Jeff Varasano’s list of world’s best pizzerias, and there is not a single oven identified as gas on the list.

Quote
IR from burning wood is the same as IR from an electric broiler.
Yes technically, other than the direction of travel, which may or may not be a good thing? I guess you could come up with something rather complicated that could closely duplicate the flexibility of a wood fire. The kiln pies I’ve seen – such as Wild Rise – aren’t even close to the pies Toby posted however.

Scott, you may be right, but I’m a long way from saying so at this point. It just doesn’t feel right to me – but I’m probably biased.  8)

Craig
Pizza is not bread.

Offline scott123

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Re: Building an oven with ultimate control
« Reply #16 on: January 20, 2012, 07:23:15 PM »
Craig, I agree, pies like Toby's made in an electric oven are an extremely rare occurrence. It doesn't speak to electric's inability to produce Neapolitan bake times, though, just that home ovens generally can't match Toby's specs. Many electric broilers just don't have the wattage to pump out enough IR to produce leoparding. With the right broiler (high wattage, tightly arranged coils), leoparding is no problem.  Since Avidan is building this oven from scratch, he can put a broiling element in it that will incinerate the top of the pizza.

And, yes, Wild Rise doesn't hold a candle to Toby. I said as much in the thread. I think it's pretty obvious that one can't go out and buy a raku kiln and expect to make the best Neapolitan pizza.  But kiln technology might be part of the answer.  I think the big problem is the shape.  Instead of the bulbous dome of a Raku kiln, the ceiling should most likely be shallow and rounded, like an inverted wok. It should also be considerably larger than the pizza and not almost touching the side of the rim. The one valuable feature that a Raku kiln does possess is the movable ceiling.  In order to maximize the impact of the IR, proximity is vital, so an oven with a ceiling that drops down to a fraction of an inch away from the pizza is a good idea.

I have been thinking about this a lot lately- why has no one come out with an electric oven with the necessary specs to make Neapolitan pizza?  I know the G3 Ferrari/Pizza Bella ovens are supposed to do something Neapolitan-ish, and, with the right modifications, I think they come close, but I'm really kind of amazed that no one has come up with an oven in the $1000 realm that can make Neapolitan out of the box.  It is SO feasible.
« Last Edit: January 20, 2012, 07:28:27 PM by scott123 »

Offline TXCraig1

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Re: Building an oven with ultimate control
« Reply #17 on: January 20, 2012, 08:32:25 PM »
Well, even if you are right, I'm going to invoke pizza snobbery and say wood is better anyway.  :-D

CL
Pizza is not bread.

Offline avidan

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Re: Building an oven with ultimate control
« Reply #18 on: January 22, 2012, 11:57:03 PM »
hey all.
thanks for the great feedback. i really appreciate this conversation about wood vs gas vs electric. i have been weighing the use of each of these in my project. from a pizza making perspective, is the largest difference a matter of humidity? ambient heat? or is this a discussion that has happened a million times and there is a thread i really need to read?
i have been looking at using electric kiln technology fairly prominently through this project, but have been weighing its value against the forced air system with wood fire. i am happy to hear everyones insight, even if this project goes against all pizza making traditions :)

Offline scott123

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Re: Building an oven with ultimate control
« Reply #19 on: January 23, 2012, 01:28:53 PM »
Avid, humidity, as far as I know, has never been discussed.  It's really not a factor.  You've got steam coming from the wood, but that's mostly being driven up and out the exhaust.  Water is also a byproduct of natural gas combustion, but, again, you've got an exhaust in place.  An electric oven won't have the same air flow, but the element doesn't generate water. Humidity doesn't play a role.

Ambient heat may play an extremely small role, but I think you'd be hard pressed to detect it. Pizza is 99.9% conduction and radiation. The ambient heat probably does play a role in pre-heating the hearth, but, once the pizza goes in, you're pretty much talking heat conducting up from the hearth and heat being radiated down/from the side from the dome and fire.

This forum has a few members who feel that smoke makes a difference to the taste of pizza.  I would probably say that most don't feel like it makes a difference, but you should be aware of the minority opinion.  I pretty firmly believe that if smoke plays a role, it's so insignificant that it's almost impossible to detect- a few seconds of doming isn't going to impart any detectable flavor.

Speaking of smoke... if you are working with wood, you will have to incorporate a firebox into your design to properly vent the fire. You will not be able to direct the unexhausted fumes at the pizza, as that will make a difference in the taste of the crust- a difference that you'll want to avoid. Unless you can find a way to send a tiny bit of smoky air at the end of the bake to somehow mimic the effects of doming, smoke will not be a part of your flavor equation.