Author Topic: brick oven vs precasted oven  (Read 1657 times)

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Offline dheeraj

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brick oven vs precasted oven
« on: December 13, 2013, 11:04:26 PM »
hi ,
can someone tell the difference in the fuel consumption  (WOOD) between a brick oven and precasted oven, assuming the diameter of 48 inch and 15inch height dome (am thinking on commercial lines)

is the difference substantial or neglegible

thanks


Offline stonecutter

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Re: brick oven vs precasted oven
« Reply #1 on: January 23, 2014, 10:09:12 AM »
Too many variables to get a definitive answer.  But all things being equal between the two types, I would say no  discernible difference.
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Offline JConk007

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Re: brick oven vs precasted oven
« Reply #2 on: January 23, 2014, 05:33:05 PM »
Real question and n my mind more important than a few sticks of wood per hour is
"Do they cook the same ?"
John
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Offline breadstoneovens

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Re: brick oven vs precasted oven
« Reply #3 on: January 23, 2014, 07:15:32 PM »
As stone cutter said their are many variable to take in consideration.

That said for the same floor size and material thickness there is a difference.
A true refractory bricked dome is about 25% more wood efficient than a regular concrete dome.
This was actual tested and measured by FGM.

The reason is the thermal conductivity of refractory bricks is better, meaning they absorb the heat faster and more efficiently than refractory concrete.
The darker color of the brick versus the light color of the concrete also allows to absorb the heat and retain the heat better. Just like a red car in the sun gets hotter than a white car.

Now as John said, do they cook the same?
That all depends on the shape of the dome, ratios and so on.
For the same dome and oven shape, brick do cook better than a concrete dome.
Bricks develop a better natural convection along with better radiation of the heat, resulting in more efficient and even cooking.

For occasional use it won't make much of a difference. For passionate wfo chef and commercial use, it can quickly make a difference.

Antoine
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Offline shuboyje

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Re: brick oven vs precasted oven
« Reply #4 on: January 23, 2014, 07:22:22 PM »

The reason is the thermal conductivity of refractory bricks is better, meaning they absorb the heat faster and more efficiently than refractory concrete.
The darker color of the brick versus the light color of the concrete also allows to absorb the heat and retain the heat better. Just like a red car in the sun gets hotter than a white car.


Normally I agree with you Antoine, but this doesn't make an ounce of sense.  Heat is not conducted to the dome, so thermal conductivity is not a factor.  Even if it was most castable refractories have a thermal conductivity at or above firebrick.  As for color, most fire brick in the US is buff while every castable I have ever seen is a dark grey, so your analysis of the function color plays is also off.
-Jeff

Offline breadstoneovens

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Re: brick oven vs precasted oven
« Reply #5 on: January 23, 2014, 07:47:46 PM »
Normally I agree with you Antoine, but this doesn't make an ounce of sense.  Heat is not conducted to the dome, so thermal conductivity is not a factor.  Even if it was most castable refractories have a thermal conductivity at or above firebrick.  As for color, most fire brick in the US is buff while every castable I have ever seen is a dark grey, so your analysis of the function color plays is also off.

Ok, let me try again to see if I can win you over :)
The fire heats the dome. The heat then travels through the thickness of the materials. That happens more quickly with the bricks.

To me the standard refractory concrete once fully heated, is almost white. See picture bellow.

Using true refractory bricks, redish color, not the buff one that you describe which are more designed to be in fire places to insulate the construction. Those bricks once heated stay fairly red.

Hope you now agree with me ;D

P.S.: the red fire bricks are very hard to find in the US as it is a food grade type of bricks and are most often imported from Europe.
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Offline shuboyje

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Re: brick oven vs precasted oven
« Reply #6 on: January 23, 2014, 08:24:12 PM »
Can't say I do.

I think it is much more likely that the monolithic construction of the castable would be more efficient at transferring heat throughout the mass due to lack of joints, but the difference would be very minimal.  I've personally never had any of my castable pieces change color at pizza oven temperatures.

The color of the brick has nothing to do with it's refractory characteristics.  I can get the bricks I like in red or buff, but Buff is just much more common.  If you want to make the claim that an american made dry pressed fire brick is not a true refractory brick I don't even know where to go from there.  The kilns your red bricks are fired in are probably made from dry pressed buff fire bricks, lol. 

Lastly,  I've dug through the regulations before to show that the NSF and FDA consider firebrick food safe, I really don't want to do it again.
-Jeff

Offline stonecutter

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Re: brick oven vs precasted oven
« Reply #7 on: January 23, 2014, 08:43:00 PM »
Not trying to be argumentative, but I have never had a problem getting red firebrick anywhere I've been.  In fact, I built my other home oven with them.  Further, I have never heard of food grade bricks....or any such designation for any type of firebrick.

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Offline breadstoneovens

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Re: brick oven vs precasted oven
« Reply #8 on: January 23, 2014, 09:32:41 PM »
I guess there is different way to look at the fire bricks.

The food grade fire bricks are made from natural clay that has a higher content of alumina. Such clay is used to make cooking dishes but also bricks for wood fired ovens.

I got the European bricks analyzed by Acme and other brick manufacturers. All said the same thing, they don't make anything of such quality.

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Offline dheeraj

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Re: brick oven vs precasted oven
« Reply #9 on: February 01, 2014, 07:02:05 AM »
brick wall
« Last Edit: February 01, 2014, 07:56:45 AM by dheeraj »


Offline breadstoneovens

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Re: brick oven vs precasted oven
« Reply #10 on: February 01, 2014, 11:55:18 AM »
Very nice. Sounds like it is going to be a great oven. What is the floor diameter? Also what dome height are you going for?
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Offline dheeraj

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Re: brick oven vs precasted oven
« Reply #11 on: February 02, 2014, 12:13:49 PM »
Very nice. Sounds like it is going to be a great oven. What is the floor diameter? Also what dome height are you going for?


i am sorry the actual post is this

http://www.pizzamaking.com/forum/index.php/topic,29977.0.html
 i am sorry i think this picture  is misleading
please view the post and do comment
thanks

Offline vtsteve

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Re: brick oven vs precasted oven
« Reply #12 on: February 05, 2014, 11:46:27 AM »
The Whitacre-Greer fire bricks have a slightly higher duty temperature, due to the lower percentage of non-refractory impurities:

Buff:  2.8% FeO3, 2000F duty temperature
Red:  4.9% FeO3,  1750F duty temperature


http://www.wgpaver.com/wp-content/uploads/2013/05/Product-Data-Buff-Firebrick.pdf
http://www.wgpaver.com/wp-content/uploads/2013/05/Product-Data-Red-Firebrick.pdf

The data sheet for conductivity only references the buff:
http://www.wgpaver.com/wp-content/uploads/2013/02/Thermal-Conductivity-of-Firebrick.pdf

Other interesting .pdfs at:  http://www.wgpaver.com/firebrick/

I built my Pompeii-style dome and floor with red bricks (my wife thought it looked better). Later, to lower the ceiling and add mass for bread baking, I added a layer of the buff bricks to the floor. It does seem less likely to burn the bottoms now (both bread and pizza). I got the buff bricks at Home Depot.