Forno Bravo Forum: The Wood-Fired Oven Community

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Deroles 04-16-2012 03:55 AM

New from NZ
 
Hi There

Finally I have found a forum that deals with the design and construction of wood ovens!
I want to make a pizza oven..but with a difference. I have had a look at the traditional designs (hundreds!) where one builds a fire in the oven and when its hot enough push it to one side and cook (pizzas etc). My thoughts are: this uses a lot of wood, takes time to get to temp (1-2 hours), can only cook for as long as the oven is hot enough (floor cools down first so pizzas don't get crispy base).
I would like to build an oven with a separate fire box underneath the oven chamber(dome shaped), with the fire venting into the oven space around the sides/back, and the roof of the fire box doubling as the oven floor (fire tiles). This way one can keep the fire going all the time, the oven base is always hot and it should be quicker to heat up as there is no need to heat the large thermal mass of the base.
Has anyone built something like this or know of a design for such a contraption. I have searched extensively on the web without success and am wondering why no one builds an oven like this as its essentially a duplicate of a traditional indoor wood fired oven. Is there some obvious drawback that I am missing.....

tonybaker 05-02-2012 04:01 PM

Re: New type of oven
 
this sounds very much like the conventional ovens seen in homes. This is how the older style wood stoves worked and they are only good for cooking as long as the fire is alight.

Deroles 05-02-2012 09:40 PM

Re: New from NZ
 
Yes I agree with you. I was thinking that such a design would use less wood for a given cooking time as it will heat up faster, it would also take less time to start up. And one could cook for as long as one likes - so if a bunch of people turn up to the party late you just feed the fire and carry on! These are the advantages I see over the traditional design. Do you see any disadvantges that I may have overlooked?

Bacterium 05-03-2012 01:55 AM

Re: New from NZ
 
I think what makes a good wood oven pizza is the high heat and short cook time :D

The high heat gives a quick cook time, so therefore caramelization of the toppings occurs very well. Also the short cook time usually results in the right crust as far as crisp yet flexible. My experience is once you start going towards a cook time of about 4mins or longer the crust is tougher/crunchier and must less flexible. Caramelization changes and toppings tend to dry out more.

Question is can your proposed design achieve that quick cook time? :confused:

I've had pizzas out of those gas fired ovens you see at hardware stores, ones with smoke chip boxes, a cooking stone etc and they just don't have the legs to get the temp up or the flavor from a wood fire.......not to say this replicates your design idea but it does demonstrate something's. Wouldnt you still have to pump in a decent amount of fuel to get the high heat, assuming you could.

brickie in oz 05-03-2012 02:21 AM

Re: New from NZ
 
Quote:

Originally Posted by Deroles (Post 130915)
so if a bunch of people turn up to the party late you just feed the fire and carry on!


Which is what most people on this forum do with their well designed ovens? :confused:

Dmendo 05-03-2012 02:48 AM

Re: New from NZ
 
4 Attachment(s)
Hi Deroles.
I'm fighting with a design of this kind. There are several ways to do this kind of design but all I've found have lacks in isolation or too much mass involved for get the goal of fast heating. you can get inspiration with some traditional spanish two chamber dome ovens.
Attachment 29373

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Also, Alex Chernov has designed the very sophisticated "six cilinder oven". Although it is intended for a vaulted cocking chamber it's possible to do round dome version of this design. This design and several more separate firechamber in his stovemaster web:
STOVEMASTER - News

And yet more heat efficient is the russian Teplushka oven. This design is initially intended as a dual purpose masonry heater plus oven. So it lacks isolation as the idea is losing heat to warm the house. Obviously is quite easy to isolate all around for keep all the heat inside. A lot of information about this oven here:
Krestianskaya Teplushka - Pyromasse
I hope you get this initial tracks inspiring.
Regards

brickie in oz 05-03-2012 03:28 AM

Re: New from NZ
 
Why reinvent the wheel? the best oven design has been around since Roman times.

Dmendo 05-03-2012 02:53 PM

Re: New from NZ
 
Quote:

Originally Posted by brickie in oz (Post 130930)
Why reinvent the wheel? the best oven design has been around since Roman times.

... maybe because thousands years after somebody invented the ball bearing?:D

It's a fact that many of us love the out of the box thinking way. And all the ways, there are many important improvements in the oven design in front of the ancient way. Refractory materials and isolation that are involved in a Pompeii design are the "carbon fiber wheel with ceramic bearings" compared to that used in the roman ovens. I've heard of traditional ovens for baking that needed a whole day for reach the baking temperatures and around 4 hour a day for keep it running... many of the ovens in this forum double those temperature in one hour.
So, IMO, the challenge is get such performance with less wood.

Regards

Lburou 05-03-2012 08:21 PM

Re: New from NZ
 
We baked ten large potatoes today, 24 hours after pizza (with no fire). Will bake some pastry tomorrow (with no more fire). Can bake the day after that (with no more fire).

We all go through many nights of dreams about the perfect oven we are going to build, wondering how to improve on a given oven design, or to start from scratch. After going through those dreamscapes, then coming to my senses, I chose to stand on the shoulders of those who have passed design refinements from antiquity through to today's pompeii oven design. Brickie said it correctly when he encouraged you to go with a Proven design. I hope you take his advice. :)

Good Luck whichever way you go. :)

thijsatteiltje 05-05-2012 03:02 AM

Re: New from NZ
 
5 Attachment(s)
Hi,

what a coincidence.. I just finished this exact idea this week, and am currently drying out my earth-oven-with-rocket-stove below.

But, I made sure to make it a hybrid design that could also work as a traditional oven with the fire on the cooking surface.

Why? Because after reading some posts on this forum and elsewhere on the net, I had a suspicion that the idea is flawed by a very fundamental idea. That even though a rocket stove gets incredibly hot, the hot gasses just don't have the conductive capacity that a bed of hot embers and open flames right on the cooking floor have.

I would love some comments about the difference between conductive and radiant heat of gas vs ember/flame.

The gasses (correct me if I am wrong but a gas is bad conductor of heat, isn't it?) rush at top speed through the dome, and out the chimney. They hardly touch the floor which, if made from fire-bricks, is very dense and needs a lot of heat.

You could of course heat the floor directly from underneath, but you'd prob. only be able to heat a small spot and have a hard time controlling the heat and preventing from getting the floor TOO hot, burning the pizza.

Plus, you run into construction problems by having a channel under neath the floor. So you need more supports. More support = more mass to heat up.

This is the only successful build I have found:
Rocket Oven.mov - YouTube

This guys oven is massive, and the stove very small, so he doesn't get it up to temperature according to his comments:
Permaculture Our Urban Design Part 8 - Rocket Oven Pt2 - YouTube

This guy also says the floor does not get hot enough:
Rocket Stove Pizza Oven - YouTube

Here are two other discussions about it on FB:
http://www.fornobravo.com/forum/f43/...ven-16759.html
http://www.fornobravo.com/forum/43/w...n-17487-2.html

I had a lot of fun designing and making the rocket stove and still hope to use it pre-heat the chamber and chimney before a start a full fire inside the chamber. Hopefully starting with a less smokey fire. (the output from the rocket stove is, as you say, completely smokeless)

I am not giving up on this idea yet, but I have to agree with some of the other repliers about the tried and true methods.

I do really appreciate your innovative spirit and would love to see some of your sketches.

- Perhaps a much bigger rocket stove? (it uses fuel at an enormous rate as it is)
-Perhaps connecting the burn chamber directly to the floor stones and have them conduct the heat while the exhaust gases take care of the dome?

Let me know what you think.

Matt


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