Author Topic: Burnt Pizza  (Read 1355 times)

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Offline doughjockey

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Burnt Pizza
« on: June 04, 2013, 10:42:25 PM »
Dear Members,

Recently purchased a gas fired pizza oven in the hope of raising the bar for my newly discovered NY style pizzas, with the help of this excellent forum. The oven is heated by a circular gas ring, 1 1/4" below the supplied 8mm thick ceramic stone. In a preheated oven, to 527F, the base was burnt in a shape which corresponded to the burner below almost instantly. Thinking it may been the thin stone so close to the burner, I installed 1" firebricks instead of the stone. The pizza was very promising and quick to cook, 3 mins, but the result is the same. Perhaps the shelf should be further from the flame. Could it be the dough hydration, too high ? Maybe the firebricks need to be tempered, used a bit, I don't know. At the same temperature my kitchen oven cooked beautiful crusts, grrrr ! I am using this dough, cold fermented for 48hrs.


Flour (100%):    639.05 g  |  22.54 oz | 1.41 lbs
Water (64%):    408.99 g  |  14.43 oz | 0.9 lbs
IDY (0.5%):    3.2 g | 0.11 oz | 0.01 lbs | 1.06 tsp | 0.35 tbsp
Salt (3%):    19.17 g | 0.68 oz | 0.04 lbs | 3.43 tsp | 1.14 tbsp
Oil (1.5%):    9.59 g | 0.34 oz | 0.02 lbs | 2.13 tsp | 0.71 tbsp
Total (169%):   1080 g | 38.1 oz | 2.38 lbs | TF = N/A
Single Ball:   270 g | 9.52 oz | 0.6 lbs


Any suggestions would be very welcome,
Regards,
Gus



scott123

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Re: Burnt Pizza
« Reply #1 on: June 04, 2013, 10:58:01 PM »
Gus, could you take a few more photos of the oven, such as

1. One shot of the entire oven chamber - with the bricks to see how much space you have around them.
2. A shot of the burner- perhaps with the firebrick removed for better visibility.
3. A shot of the control panel

BTUs on the burner?

No broiler (top burner), correct?

What flour are you using?

Is 527 as high as the oven will go?

Is this 527 on the dial or a 527 stone reading with an infrared thermometer.  Do you own an infrared thermometer?

Do you still have a kitchen oven that goes to 527?

What is the shelf dimension and what is the hearth dimension? (or maybe just a brand name/model number so we can look  up specs?)

I hate to be the bearer of bad news, but I think you bought a less than quality pizza oven- at least, from a NY style perspective. It should be fine for American/chain style, which is probably what many buyers use it for. Don't worry, though, we should be able to get a nice, relatively crispy 7 minute bake out of it, as long as  the burner has enough BTUs.
« Last Edit: June 05, 2013, 12:23:37 AM by scott123 »

Offline Chicago Bob

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Re: Burnt Pizza
« Reply #2 on: June 05, 2013, 12:00:15 AM »
Gus, could you take a few more photos of the oven, such as

1. One shot of the entire oven chamber - with the bricks to see how much space you have around them.
2. A shot of the burner- perhaps with the firebrick removed for better visibility.
3. A shot of the control panel

BTUs on the burner?

No broiler (top burner), correct?

What flour are you using?

Is 527 as high as the oven will go?

Is this 527 on the dial or a 527 stone reading with an infrared thermometer.  Do you own an infrared thermometer?

Do you still have a kitchen oven that goes to 527?

What is the shelf dimension and what is the hearth dimension? (or maybe just a brand name/model number so we can look  ups specs?)

I hate to be the bearer of bad news, but I think you bought a less than quality pizza oven- at least, from a NY style perspective. It should be fine for American/chain style, which is probably what many buyers use it for. Don't worry, though, we should be able to get a nice, relatively crispy 7 minute bake out of it, as long as  the burner has enough BTUs.
The Master at work....you are amazing dude. Relentlessly giving...I just love watching threads like this develop. Thank you sir.  :chef:
"Care Free Highway...let me slip away on you"

Offline doughjockey

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Re: Burnt Pizza
« Reply #3 on: June 05, 2013, 12:26:46 AM »
Thank You very much for the reply Scott,

BTUs - 21MJ/h
Curved top
Using a baker's flour - don't know its details
The oven's temp gauge is pretty useless, shows 300C, actual is 270C, checked with a digital sensor. I have yet to buy an infrared thermo
My kitchen oven will go to that and higher if I use the broiler
The internal size of the oven is 19.75" W 18.5" D 13.75" H has two wire shelves as well as the stone above the burner

After the first pizza burnt last night, the next one went on the stone above on a shelf which was 3.5" above the brick shelf, wasn't burnt, base was perfect, much less oven spring though. Are you thinking a lower temperature setting ? Maybe it is a dog and that is why the guy I bought it from sold it on Ebay, after what appears to be minimal use. Had no burn evidence on the stone. The PDF brochure is not accepeted in the attachments. The oven can be seen @ www.gasmate.com.au The last photo shows the firebricks already raised by 1 1/4 "

Regards, Gus

« Last Edit: June 05, 2013, 12:30:35 AM by doughjockey »

scott123

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Re: Burnt Pizza
« Reply #4 on: June 05, 2013, 01:15:14 AM »
Bob, thanks for the kind words. I aim to please  ;D

Gus, I've got some good news and some bad news.

The bad news is that, yes, it's a bit of a dog (although not an overpriced one).  The good news is that you can teach it some tricks  ;D

The top is insulated, right?  Two layers of metal, something in between? When the oven's running, the top exterior isn't incredibly hot, right? As long as it's insulated, you should be in good shape.

I compared the energy output to other pizza ovens and they match up, so you've got the power. What you don't have, that every gas deck oven has, is deflection- a way of taking the heat past the stone and up and over the pie- without superheating the stone. I'm also not terribly happy about the 270C peak temp, but there may be some ways around that.

I've come up with a homegrown approach to mimic commercial deck oven thermodynamics here:

http://www.pizzamaking.com/forum/index.php/topic,21503.msg217026.html#msg217026

Before you try that, though, see what kind of heat balance you get just by putting the firebricks on the top shelf. Make sure the only thing in the oven is the firebricks.  Regardless of the advertising photos you see, this oven will never bake multiple pizzas at a time- unless you want deprived oven spring from long bakes.

The top shelf position for the bricks will extend the pre-heat, but other than that, it should help even out the bake, both on the top and the bottom of the crust. How long are you pre-heating for now?

The oven thermostat is usually located in one of the top corners, can you see if you can locate it? It's usually a long probe.

An IR thermometer is really critical for this kind of oven for confirming stone temps. They're really cheap from Hong Kong. Let me know if you need a link.

If you can, find out the brand of the flour, or, at least, the protein content, as the protein content dictates the quantity of water to use. How does the dough feel when you're working with it? A bit droopy, a bit taught or just right?

You've got a broiler in the kitchen?  What are the shelf dimensions there?
« Last Edit: June 05, 2013, 01:16:50 AM by scott123 »

Offline jeffereynelson

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Re: Burnt Pizza
« Reply #5 on: June 05, 2013, 01:54:28 AM »

Before you try that, though, see what kind of heat balance you get just by putting the firebricks on the top shelf. Make sure the only thing in the oven is the firebricks.

Ya that oven has 3 racks and if he moves up the wire grate and the bricks, I bet you it would come out way better. He would be pretty close to the dome. I'm curious to see what you guys come up with and can do.

Offline doughjockey

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Re: Burnt Pizza
« Reply #6 on: June 05, 2013, 08:26:55 PM »
Thank You again Scott, your attention to my (self inflicted) problem is really extraordinary !

The double wall has no insulation inside, which I thought was strange, together with the chimney arrangement. It is separated into two tubes. The inside section vents the case by drawing air in at the bottom of the case, reducing the heat of the external surface. The inside tube vents the oven interior. I have considered disassembling the case and installing insulation between the walls, and choking off some of the interior chimney to get higher temps inside. It sounds like you are implying something  like that by asking about insulation.
It seems that the design uses airflow to reduce outer case heat. There are stickers both sides warning about touching the hot surface. Would you think that because of this, that there is a constant heat loss because of the way it is designed ? So, bricks get very hot while the interior loses heat. Maybe they are trying to make sure no user gets a burn and sues the pants off them....

The only temp sensor is located right next to the gas ring. I imagine this reduces gas flow according to the "setting" of the dial, though no temp numbers are shown on it. So, no oven temperature is monitored. This may be part of the dogginess of it ?
 Last night's experiment, moving the brick shelf up by 1 1/4", was already a marked improvement to the cook. There was only marginal burn, 6 minute cook, less oven spring, overall  an ok pizza, at this stage of my development in the art. I did put the pie in @ 250C - 482F. Stood there transfixed, nervously looking for any sign of burn. This is an exciting hobby !! I wouldn't want to see the missus chewing the toppings of another burnt to smithereens pizza. I will take your kind advice and move the bricks up to the top level next.
Next research for me is the discovery of the flour characteristics. The dough  feels a little droopy, quite soft, but easily managed, and nice flavour.
The kitchen oven shelf is 18" W x 14" deep.
The preheat is an hour, perhaps not long enough for firebricks ? I have yet to learn what to do when the temp reaches the desired level, given there is no indication of "idle" on the control dial.

Regards,
Gus
« Last Edit: June 05, 2013, 08:29:11 PM by doughjockey »

scott123

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Re: Burnt Pizza
« Reply #7 on: June 05, 2013, 09:04:11 PM »
Hmmm... interesting stuff there, Gus.

So, the whole oven is double-walled, but the inside of the double walling vents at the top?

I can see how that might make for a cooler/safer outer shell, but it's horrible for maintaining temperatures.  It's a bit like saying "I don't mind using tank after tank of propane to heat the outdoors."  ;D Bad bad doggy. These guys are cheap! Keep using the oven as is, but definitely, when you get a chance, get your hands on some rockwool and/or other high temp fiber insulation and fill that gap.

Be very careful with blocking the inside chimney, though. If you block that too much and the gases don't exhaust, the burner will go out while the gas still flows, and that could get dangerous. You might be able to restrict it a bit, and keep a little more heat in the oven, but I'd be careful.

But definitely insulate between those walls.

I'm going to need to some research on that thermostat, as I'm not familiar with that design. Edit: correction after info from Bob (thanks, Bob!)

The thermal mass in those firebricks usually takes a long time to heat up, but it looks like you're achieving temps pretty quickly. Still, though, for the top shelf, I'd probably pre-heat for 90 minutes.

Have you order your IR thermometer yet?  >:D
« Last Edit: June 05, 2013, 09:27:10 PM by scott123 »

Offline Chicago Bob

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Re: Burnt Pizza
« Reply #8 on: June 05, 2013, 09:17:33 PM »
The thing on the right(white porcelain) is the ignitor. Thing on left is just a thermocoupler, flame keeps it hot; if flame goes out coupler reacts and shuts off gas.
"Care Free Highway...let me slip away on you"

scott123

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Re: Burnt Pizza
« Reply #9 on: June 05, 2013, 09:24:28 PM »
Doh!  That makes sense.  Thanks, Bob!

So the control knob has nothing to do with any kind of temperature setting, it's just like any old gas grill, it turns the gas up and down- increases the flame and decreases the flame.

I was hoping for something a bit more sophisticated, but it is what it is.

Gus, confirm that the control is just more or less gas/more or less flame and then just crank it for 90 minutes and see what she does (and start shopping for either loose or blanket high temp insulation).
« Last Edit: June 05, 2013, 09:28:56 PM by scott123 »


Offline nick57

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Re: Burnt Pizza
« Reply #10 on: June 05, 2013, 10:10:10 PM »
I wonder if there was someway to move the thermocouple a little farther away from the flame. Maybe that would help in increasing the temps. You might have to try a couple of times to get right distance from the flame. Either that, or just bypass the thermocouple and run the flame to your desired temp.
« Last Edit: June 05, 2013, 10:15:30 PM by nick57 »

Offline Chicago Bob

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Re: Burnt Pizza
« Reply #11 on: June 05, 2013, 10:16:03 PM »
I wonder if there was someway to move the thermocouple a little farther away form the flame. Maybe that would help in increasing the temps. You might have to try a couple of times to get right distance from the flame. Either that, or just bypass the thermocouple and run the flame to your desired temp.
Wrong kind of party Nick...thermocoupler is only a safety device; wind blows flame out,coupler shuts off gas. To increase burner output you would need to up fuel pressure and/or drill out burner hole's size and then adjust venturi air flow.
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Offline nick57

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Re: Burnt Pizza
« Reply #12 on: June 05, 2013, 10:29:31 PM »
You are be right, I was thinking of an over temp coupler. There should be some way to keep the flame on at full bore without a safety cutoff. Of course I would only do this outdoors. I bypassed my controls on my gas grill and really got some high temps. I could keep the flame at the maximum for as long as I wanted. In the winter it was fun to go out in several inches of snow and cook some filet mignon's  You just have to be safety conscience.

Offline Chicago Bob

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Re: Burnt Pizza
« Reply #13 on: June 05, 2013, 10:43:20 PM »
You are be right, I was thinking of an over temp coupler. There should be some way to keep the flame on at full bore without a safety cutoff. Of course I would only do this outdoors. I bypassed my controls on my gas grill and really got some high temps. I could keep the flame at the maximum for as long as I wanted. In the winter it was fun to go out in several inches of snow and cook some filet mignon's  You just have to be safety conscience.
Just please be careful and don't go burning yourself up Nick....I still need more training/tips on how to make your  cracker pies.   :chef:
"Care Free Highway...let me slip away on you"

Offline nick57

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Re: Burnt Pizza
« Reply #14 on: June 05, 2013, 11:01:22 PM »
Even though I am an artist and grew up in a restaurant environment . In my past life I was a tech guy, from lawn mowers to cat scanners.  I installed the first MRI machine in the US. So, my first thought is "Safety First" I have no problem with bypassing safety devices, but if you are not sure of your circumstances then do not  do what I suggest.

scott123

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Re: Burnt Pizza
« Reply #15 on: June 05, 2013, 11:48:40 PM »
Nick, you fell into the same trap that I did.  The 'safety' device is what keeps the burner going, not what shuts it off.  This device is full bore until the propane runs out.

Offline Chicago Bob

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Re: Burnt Pizza
« Reply #16 on: June 05, 2013, 11:55:26 PM »
Nick, you fell into the same trap that I did.  The 'safety' device is what keeps the burner going, not what shuts it off.  This device is full bore until the propane runs out.
Exactly....but all he really needs though is just your common ordinary "Spinal Tap" mod, mate.  ;)
You have one of these I'm quite sure; right Scotty?

« Last Edit: June 05, 2013, 11:57:09 PM by Chicago Bob »
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Offline doughjockey

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Re: Burnt Pizza
« Reply #17 on: June 06, 2013, 12:47:43 AM »
Scott, thanks again !
I am insulating as we speak, and ordered TWO infra readers, they were so cheap, I thought surely one will %$# itself in short order.......

Chicago Bob,

Thanks for your input as well ! By the way, an earlier post of yours introduced me to Rory Gallgher, fantastic !, I have ordered one of his DVDs, I owe ya !

Regards, Gus

scott123

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Re: Burnt Pizza
« Reply #18 on: June 06, 2013, 01:14:42 AM »
You have one of these I'm quite sure; right Scotty?

Every oven I own goes to 11 and I've got the label maker to prove it  :-D

Gus, sounds good.  For what it's worth, IR thermometers don't fail as much as you think they would.  The laser pointer tends to go, but otherwise, it's very rare that I hear about these things breaking down.

Offline nick57

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Re: Burnt Pizza
« Reply #19 on: June 06, 2013, 10:36:26 AM »
Yeah, I was wrong on my assumption. I had one too many adult beverages last night, but I had fun. I think the burner may be too small  for the heat output you are looking for. Insulation may help. You can get replacement burners, and maybe you could find one with more BTU output and modify it to work in the oven. I don't think drilling the holes bigger would help. I actually saw something similar at Sam's The oven part looked the same, but it was mounted to a cabinet that held the propane tank. I think they were asking about $269. It looked pretty cool, but I thought it was just too lightweight for making pizzas. I think insulating may be the cheapest fix, and would be my first step in any modification. If you can hold the heat in, it should raise the temps a little.