Brick oven reconstructed to a steel one

[david s]

Re: Brick oven reconstructed to a steel one

My dense firebricks are exactly 2kg/ litre, some are even denser than this. My IFB's are 0.5 kg/litre. Going on your dimensions if they are IFB's which I suspect they are not they should weigh around 0.8 kg.

[cobblerdave]

Re: Brick oven reconstructed to a steel one

david. There is another "cartable" in your post that needs to be corrected to castable I read your post and started looking for "cartable" in the dictionary then I knew it was a spilling mistake and that you meant castable. Then I was surprised that you fixed one of them ..
This may be a mad idea, but I'm trying to make my oven fast to heat up. I don't need the retained heat cooking. What is the benifit (to me) of waiting 90 minutes as in your castable oven, or even 45 minutes as in Wiley's oven which has steel in it cladded with basalt in order for the dome to clear while I can wait just a few minutes or up to 15 in an oven with less thermal mass? My belief is that the thermal mass favors two things: heat consistency and retained heat cooking, and that the thermal mass contributes nothing to getting a 2 min pizza out of the oven. The 2 min pizza is achieved by the current temperature inside the oven which is achieved by adding more fuel.
If I am cladding my oven I don't want to go beyond 0.5" thick. If I have to go thicker I prefer to not clad it at all; just 2 mm of steel with aluminum foil over it then the ceramic blanket. So what do you see?

G'day V12
Metal shell,insulated on the outside, internal heat source.
What you have now described is basically your domestic oven, only thing missing is the open shelving really.
In my pre bravo forum days I used to cook pizza for my family in a domestic oven. Having worked in a pizza place previously I understood you needed a bit of thermal mass under the pizza otherwise it just would cook fast enough. My solution was using a thick aluminum backing dish turned upside down at the top of a well heated oven. The results were... Well except able enough for a couple of hungry children and they never complained, but they were less than perfect.
I've experimented with pizza on pizza stones on BBqs and under the grills of my gas domestic stove since then. The results were except able but not on par with WFO with a bit of mass.
I myself recon you should include a couple of ins of mass at least to you plan to make it work.
You have to remember the fire is there to replenish the heat stored in the mass of the oven. If you have no mass adding a pizza drops the heat straight away. You want that bank of heat that cooks things straight away .
You might want to experiment with a pizza stone in your domestic oven to find out whilst your supplies arrive . There is section in the forum worth reading.
Can't be bad especially if the experiments are worth eating
Regards dave

[v12spirit]

Re: Brick oven reconstructed to a steel one

They are 3.2 kg each. They are exactly fire bricks .

[david s]

Re: Brick oven reconstructed to a steel one

There is a question I have about ceramic insulation blankets. Is it toxic? I mean after carrying it into home my hands started to rub a little and I had a kind of a cough! It lasted for just a few minutes then every thing was OK.

It depends on what product you have. Some insulating blankets are a class 2 carcinogen. That is, tumours have been found in rats but to date none in humans. Some blanket like Morgan Superwool is exonerated from this classification as the fibres used are partly soluble. Check the MSDS on the product you have.

[v12spirit]

Re: Brick oven reconstructed to a steel one

Mates,

I could (eventually) find IFBs, but they are rather expensive. They are 5.6 $ each. That is rather expensive for me because I'm planning to build another oven in the Garden, and insulating the hearth for both will cost as much as 4 ceramic blankets each of which is sufficient for insulating the dome of one oven.
I've got a crazy idea that I would like to justify by the forum.

Since I'mm building with 100% steel, the hearth will have a self support ability. I'm thinking of wrapping the whole steel oven (including the hearth) with the ceramic blanket, and let the oven support itself by means of 3 (or more) legs fixed to the oven base by screws and nuts, but I have two worries:

1- the legs may impede the insulation, being heat conductive.
2- the the build is made of 2 mm thick steel sheet. (I can't go thicker for the dome, but I can go thicker for the hearth). I'm afraid that the the hearth will start to deform due to heavy utensils (roasts, vegs, ..) being fed into the oven over the years and due to the hearth being self supported with no supporting insulation underneath. So, do I thicken the layers of insulation blanket under the hearth until the blanket is almost compressd tightly to get a kind of support? or do I use a thicker steel sheet for the hearth to strengthen its "self-support" ability? The second choice makes me worried that the thermal mass of the dome gets less than the thermal mass of the hearth which may result in improper heat consistency i.e. a cooler hearth.

So guys, what do you think?

[david s]

Re: Brick oven reconstructed to a steel one

Some cal sil board would be a better solution. But you could also try using a few IFB's spaced out to support the floor and fill in-between with blanket.

[v12spirit]

Re: Brick oven reconstructed to a steel one

Thank you. That's a great idea!

[hubert_s]

Re: Brick oven reconstructed to a steel one

If you are concerned about the steel thickness under the hearth, couldn't you just put some bracing underneath, e.g., an I or T profile or just tubing?

[Laurentius]

Re: Brick oven reconstructed to a steel one

Hi V12,

If you wrap the steel oven in the ceramic blanket, the only purpose it will serve will be to keep outside of the oven from getting hot. I think that you need some thermal mass to made the oven beneficial of the insulation.

[v12spirit]

Re: Brick oven reconstructed to a steel one

Thank you mates for your input.

Hubert, That is a vital alternative if I fail to get the FBI and become compelled to use the ceramic blankets merely. Thank you for your suggestion.

Laurentius, What you payed my attention to is really a a concern that I've been afraid of. Regardless of the benefits of the thermal mass, I see the price for having it outweigh the benefits I'm going to gain from it, so I'm trying to end up with an oven that makes use of the majority of the fuel right for cooking, rather than consuming the majority of the fuel for heating up and then storing far more heat than I need. My theory (not proven yet) is that the high thermal conductivity of the steel together with a tight insulation and a generous heat source inside the oven will do the job in minutes. Heck, The whole cooking in a 400 degrees Celsius oven takes a couple of minutes per piece, and if I'm supposed to feed a large family and I need 15 "door-size" pieces, I'm supposed to be done in less than an hour which is less than the time needed to clear a brick oven.
What I said is just a speculation. I'll try the steel oven with no thermal mass, but if I find it working improperly or inefficiently I will be adding some thermal mass eventually. Thanks for your input.

PS: Although I don't intend to add a thermal mass to my fuel efficient oven, I am becoming jealous from those who enjoy multiple-day-heat-retained-cooking and would like to build a brick oven in the garden. What impedes me is my family who don't like me spending too much money on oven mania.

[Laurentius]

Re: Brick oven reconstructed to a steel one

The only thing the blanket will do for you is to stop heat transfer to the outer shell. Ceramic material here was as expensive as my thermal mass(bricks).

[stonecutter]

Re: Brick oven reconstructed to a steel one

Thank you mates for your input.

Hubert, That is a vital alternative if I fail to get the FBI and become compelled to use the ceramic blankets merely. Thank you for your suggestion.

Laurentius, What you payed my attention to is really a a concern that I've been afraid of. Regardless of the benefits of the thermal mass, I see the price for having it outweigh the benefits I'm going to gain from it, so I'm trying to end up with an oven that makes use of the majority of the fuel right for cooking, rather than consuming the majority of the fuel for heating up and then storing far more heat than I need. My theory (not proven yet) is that the high thermal conductivity of the steel together with a tight insulation and a generous heat source inside the oven will do the job in minutes. Heck, The whole cooking in a 400 degrees Celsius oven takes a couple of minutes per piece, and if I'm supposed to feed a large family and I need 15 "door-size" pieces, I'm supposed to be done in less than an hour which is less than the time needed to clear a brick oven.
What I said is just a speculation. I'll try the steel oven with no thermal mass, but if I find it working improperly or inefficiently I will be adding some thermal mass eventually. Thanks for your input.

PS: Although I don't intend to add a thermal mass to my fuel efficient oven, I am becoming jealous from those who enjoy multiple-day-heat-retained-cooking and would like to build a brick oven in the garden. What impedes me is my family who don't like me spending too much money on oven mania.

Thermal mass doesn't serve a one dimensional purpose. It also helps even out and distribute heat in addition to storing it.

A wood fire is a dynamic heat source, and a steel only shell is going to be a temperamental oven. Being extremely conductive, I feel like your main challenge with using only steel is going to be not burning food when running a live fire, and/or not being able to achieve balanced cooking.

[v12spirit]

Re: Brick oven reconstructed to a steel one

Thank you Stonecutter for your inputs here and on "basalt" thread. I may be adding some thermal mass eventually. But the experiment is worth trying.

[Laurentius]

Re: Brick oven reconstructed to a steel one

Thank you Stonecutter for your inputs here and on "basalt" thread. I may be adding some thermal mass eventually. But the experiment is worth trying.

Your quote, why is this......Artemus Ward, I think?

[v12spirit]

Re: Brick oven reconstructed to a steel one

When I quoted "basalt" I was referring to my thread concerning basalt.
BTW what did you mean weh you brought up Artemus Ward?