#1  
Old 06-07-2007, 03:58 PM
Serf
 
Join Date: Jun 2007
Location: cozumel Mexico
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Default hybrid

Dear Forum. I am planning a pizzeria here in Cozumel and could use some advice on building my oven. First I wonder if someone could take a look at the oven that inspired me to try to build my own at the following link

w.hornosartesanos.com/hh-meneses.htm to see what I am trying to hybridize into a pizza oven in fact any feed back would be greatly appreciated. Looking at the Pompeii specs I noticed that for every 6 inches of increase in diameter of the cooking area there is 1 inch increase in vault height and that ratio applies to either the Neapolitan or the Tuscan version.

If I apply that ratio across the board to a 72 inch oven the vault would be 20.5 in for the Neapolitan or 25 in for the Tuscan versions. Considering the concern about the cooking surface being too hot with the high duty fire brick that I plan to use and the comment made at the Forno Bravo website (Starting the Oven Dome) about the exaggerated difference of opinion about the two different styles of ovens I wonder if building the Tuscan model (because of the brick type) might be the way to go. What I would like advice from the forum is thermal mass 3 inches or more? I know that there is no such thing as too much insulation. As far as insulating the hearth an opinion on using crushed glass and coarse sea salt like in the Spanish Oven (from now on referred to as the SOB) instead of vermiculite and cement and how much insulation 4-6 inches? In building the lower compartment (that I will from now on refer to as in it’s literal translation the Burner) the Spanish builder states that the Burner should be sufficiently reduced so it does not cool off the oven and sufficiently ample so one can make fire and give it other uses. I think the Burner would be useful in keeping the oven temperature and fine tuning the same. However, remember one fires this oven the same way as the Pompeii on the oven floor and when it reaches temperature one pushes the embers down to the Burner through the opening at the back, I'll call that the Chute and that done one has the whole oven floor as cooking area ( I find that a very appealing bonus in a commercial setting). Upon looking at the pix on the SOB website and seeing how the fire goes up the Chute from the Burner and hits the dome at the back of the oven I feel that one could effectively maintain the oven temp in this fashion, if it doesn’t we will maintain the temperature the traditional way. Hence the questions. It looks as if I want a hybrid, I think is worth the risk, the only downside that I see is that the Burner won’t be able to maintain temp. I think this is one of those times that it worth trying to have your cake and eat it too!

So in recapping, the following are points that I require input and advice on from the resident sages in the forum.



1. Considering the high duty brick that I intend on using and the Burner compartment that I wish to include, should I go with a Tuscan or Neapolitan dome in height?



2. In the hearth insulation, which media to use Pompeii (vermiculite&cement) or SOB(crushed glass&coarse salt) and how much (in inches) or high tech isolpac. Would additional thermal mass (Island Hearth) in the oven floor be recommended? We plan to be open 11hours a day.



3. For dome insulation, it will be a round Igloo, vermiculite & mortar or fiberglass as in the SOB or a combination of both? or tech isulfrax? and how much insulation in inches? The place will have A/C and I wish to make the kitchen and restaurant as cool as possible.



4. It will be closed vent, with a lever / guillotine glass door, with a 10 in chimney with a flue to help controlling combustion.



5. The opening will be 33 in wide and 12 in high since we’ll be making 20 in NYC pies. A friend referred to the pizza I'm trying to make as Neo-Neapolitana

6. I might not find Portland cement in Mexico, what qualities should I look for in the cement for this project?



7. Last question….. WILL IT FLY??????????????



Please allow me to thank you in advance. My best regards. dmanfish
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  #2  
Old 06-07-2007, 10:30 PM
DrakeRemoray's Avatar
Il Pizzaiolo
 
Join Date: Mar 2006
Location: Littleton, CO
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Default Re: hybrid

Wow that is a really interesting site. too bad my spanish is so malo...

Here is a clickable link for everyone:
HORNOS ARTESANOS DE OBRA

I think it is an interesting idea. Not sure at all if it would keep the oven at 700 degrees, but if you are cooing 20" pizza do you really want it that hot?

One suggestion I have is to remove the vent from the dome and use a vent at the mouth of the oven like the pompeii plans. Otherwise I think you will lose a lot of heat up the vent.

Very cool.

Drake
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  #3  
Old 06-08-2007, 05:18 AM
CanuckJim's Avatar
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Default Re: hybrid

Drake, Dman,

I, too, think this is an interesting idea, but I would definitely move the vent forward to reduce heat loss. As for the crushed glass, sea salt idea, it would be fine if they were all that's available. I'd go as tech as possible with the insulation, and a lot of it. Something like Insulfrax batts, chicken wire, vermiculite/Portland. This is particularly necessary in a commercial setting where you don't want to spend the earth on AC. I would definitely spend the money and go for a double or triple wall insulated chimney instead of traditional masonry for the same reason.

Not at all sure that the chute will keep the oven floor hot enough for pizza. It might work on the dome, though. Without a sufficiently hot floor, the pizzas will likely cook unevenly, especially toward the mouth of the oven, and especially for such large pies. Therefore, you'd lose the real estate you picked up by not having a live fire in the oven.

The Spanish site shows black mortar being used for the brick. It's refractory mortar, and I'd definitely go that way for a high-use, high-heat oven such as the one planned. For the perlite mix, I'd source Portland, either in Mexico or import it. You won't need that much.

I'd do the math and make sure the large door opening works with the volume of the oven you plan. Otherwise, you might run into problems with draw.

I'd go for a higher dome with the bricks you want to use, but, again, do the math for the door opening. Depends on the rating of what you have, but I'd use isolpac, probably about 4 inches.

It's one of the tenets of WFOs, but it's worth pointing out that you only get as much heat as you put in. What type of wood is available to you? You'll need something with a high BTU content to do this efficiently, but I have no idea what grows in your location. It must be very well seasoned, too.

Keep us posted on what you decide.

Jim
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  #4  
Old 06-08-2007, 07:32 AM
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Join Date: Apr 2007
Location: Mississippi
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Default Re: hybrid

I concur with everything these guys have written. Floor heat definitely would seem to be the shortfall in my humble opinion. I am just wondering if you could overcome some of that by choosing not to insulate the floor directly beneath the floor of the oven and rather insulating beneath the burner box. You could then perhaps pour a level top for the burner box out of castable refractory and then take advantage of absorbed heat through the roof of the burner box to heat the floor of the oven, it might also be better to lay the floor inside the walls of the oven using firebrick splits to reduce the distance that absorbed heat would have to travel. This kind of combines the ideas of the "black oven" and a "white oven." You could then heavily insulate the dome.

Definitely an interesting idea.
All the best!
Dutch
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  #5  
Old 06-08-2007, 08:04 AM
jengineer's Avatar
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Location: Garden-A, South California
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Default Re: hybrid

Ask translation

arrgh didn't work - stand by

2nd try
translatted

dang that was not easy!

Last edited by jengineer; 06-08-2007 at 08:15 AM.
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  #6  
Old 06-08-2007, 09:08 AM
jwnorris's Avatar
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Location: Orange, CA
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Default Re: hybrid

On the translated page, I find it interesting that the author refers to building the "cave of the devil." And, for those of us who truly enjoy WFO building and cooking I find the name appropriate.

This is indeed and interesting concept and it seem to work. If anyone on this forum does build on I look forward to the tale of its use.

Additionally, if you click the link on the bottom of the translated page, it takes you to the home page. There you will find other oven links along with a couple of links to wood fired grills that are being discussed on another thread.

J W
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  #7  
Old 06-08-2007, 04:48 PM
Serf
 
Join Date: Jun 2007
Location: cozumel Mexico
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Default Re: hybrid

Gentlemen. I am very encouraged by your various replies. I'll elaborate a little more to get more direction from the forum. C Jim, the brick I am using is high duty,dry press fireclay brick suitable for boilers, it's 36%Alumina 58% Silica it has a temperature equivalent of 3123oF, reheat contraction & expansion at 2550oF (3%). Thermal conductivity at 800oF is 8.2 BTU.in/hr.ft2.Fo, those are the stated specs.
I will go forward with the Pompeii vent as advised,
and go high tech an thick with the insulation including the chimney. But I'm at at a loss for the formula for doing the math for the opening size and the draw factor. The wood here is both hard, soft and in between, we have lots of uprooted trees from hurricane Wilma, it is pretty dry we suffer from forest fires in the Yucatan peninsula from draughts. Any consensus from the forum about Dutchoven's suggestions on isulating the burner box instead of the oven floor? Any insulation above the castable refractory? Laying the floor inside of the oven?
And a curve ball....... any opinion on burning coal in the oven OR a combination of both? Just trying to keep my education interesting.
Thanks again for sharing the knowledge. dmanfish
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  #8  
Old 06-08-2007, 05:01 PM
Dutchoven's Avatar
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Location: Mississippi
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Default Re: hybrid

For the suggestion I gave there should be no insulation above the castable. You would not want to inhibit in any way the transfer of the heat through the arch brick in the burner box to the floor bricks of your oven. You would be able to lay the floor the same way as in the pompeii instructions but you may want to use thinner brick as they would heat to cooking temp quicker. As for the coal question, it is my understanding that the design for coal fired ovens is very different from that of wood fired ovens. I am nearly 100% sure that you should NEVER burn coal in a wood burning oven....could be fatal...also coal does not burn actively like wood...therefore there is not as much reflected(top) heat which is quite important for really good pizza.
I hope this sheds a bit of light!
Best
Dutch
P.S. From my research most ovens have a door height to dome height ratio of between 5.7-6.3 to 10. That is what is acceptable to leave enough space for the oven to "breathe". As far as opening width I will defer to some other members of the forum.

Last edited by Dutchoven; 06-08-2007 at 05:04 PM. Reason: lack of attention
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  #9  
Old 06-18-2007, 04:20 PM
Unofornaio's Avatar
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Join Date: Jun 2007
Location: Central, California
Posts: 323
Lightbulb Re: hybrid

Everyone,
You know the original post has been in the back of my mind for a couple of weeks now. My first concern was as Jim mentioned about the floor area but today I was thinking.... really, what would be the difference between this firing method and an oven with a gas burner at the rear? I also thought of a similar design change mentioned by Dutch to address the floor heat issue. Then I thought this would be tricky because wouldn't you would need a pretty good fire going in the fire box to keep the dome up to temp? which might keep the floor too hot..know what I'm saying? You would have to calculate the floor thickness to compensate for the heat directly under it. Perhaps thats why it is built the way it is??? who knows. I checked the site and FB makes an oven with a burner in the rear so I'm sure it works?? How does the burner fired FB deal with the floor heat issue?
I'm particularly interested in this design because I have decided I will be adding a small pizza oven (as opposed to a bread oven) into my BBQ design (see told you guys it would change) and I think I'm going to use this design concept (separate box) I really like it. I do agree it could use some tweaking here and there. any thoughts?
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  #10  
Old 06-19-2007, 04:47 AM
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Join Date: Mar 2005
Location: Pebble Beach, CA
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Default Re: hybrid

Hey Uno,
I am feeling pretty dense here. Can you explain again how you are thinking of building a separate firebox? I am having trouble visualizing it.

One place where you ocassionally see a separate firebox (either on the side or in the back) is in the rotating ovens. You need a separate place for the fire to live (either gas or wood) that is not on the round turning floor.

In terms of heat and the cooking floor, the Modena oven has a very nice burner that bounces a huge amount of heat down onto the floor from the dome. That is what keeps the cooking floor humming along at pizza heat when you cook with gas. The flame itself is pretty awesome.

James
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