Brick oven reconstructed to a steel one

[cobblerdave]

Re: Brick oven reconstructed to a steel one

G'day
After cutting a few 12 mm slices for brick veneer, I broke a few just cutting them. Brick is pretty delicate at those thicknesses. Then considering the forces put on them by uneven expansion! I don't know if they would survive.
But you don't know till you try I suppose.
Me I'd keep plan B in the background like cutting some 25 mm 30 pieces you could always use either as a brick veneer dependent on what works out.
As for pinning the oven down its sounds heavy enough not to move, adding some pins or screws even in to a soft surface would be enough to stop any movement starting
Regards dave

[david s]

Re: Brick oven reconstructed to a steel one

I agree, thin slices of dense firebrick are highly likely to crack. You may do better chasing some kiln shelves which are stronger. They are usually about 19 mm thick, but you can get them as thin as 10 mm. The thicker ones would be my choice. The extremely rapid rise in temp from a WFO is what kills the refractory. The kiln shelves and firebricks are designed to withstand more than double the temps we use, but they don't like extremely rapid rise and the thinner you go the more likely is their failure.

[v12spirit]

Re: Brick oven reconstructed to a steel one

I see. I may not be considering 1 cm either. Two other choices that sound a little bit hillbilly..
First is to lay a layer of the 5 mm thick floor tiles upside down. I have lots left after kitchen decoration. The upper side is smooth but the other side is porous. They may crack under thermal cycling but will remain in place.
Second is to stretch a thin layer of home brew on the floor using a trowel.

[david s]

Re: Brick oven reconstructed to a steel one

I would expect both those solutions to fail, but give it a try and prove me wrong.

[v12spirit]

Re: Brick oven reconstructed to a steel one

As for pinning the oven down its sounds heavy enough not to move, adding some pins or screws even in to a soft surface would be enough to stop any movement starting

I live in an Earthquake Zone .

[cobblerdave]

Re: Brick oven reconstructed to a steel one

I live in an Earthquake Zone .

Gday V12
I live in a cyclone zone.
The roof tiles wired to the trusses.
Which in turn are connected to the top plates with fish plates.
The top plates are bolted thought the walls with screwed rods tho the joists and bearers.
The bearers are then bolted to the reinforced cement piers. At 3.5 mtrs tall they go underground another 2 mtres.
An earthquake.
The ovens on a floating slab and probably survive.
Regards Dave

[david s]

Re: Brick oven reconstructed to a steel one

I live in an Earthquake Zone .

Those would be man-made earthquakes in Syria wouldn't they?

[v12spirit]

Re: Brick oven reconstructed to a steel one

Those would be man-made earthquakes in Syria wouldn't they?

Exactly. a few "man made earthquakes" a week is not too much. 200-600 K.g drum of explosives thrown from 4000 m high, will make the kitchen need redecoration if fell a few houses far. Fact. That is why am concerned to fix the light oven. Am fine. Am still alive and healthy so far .

[v12spirit]

Re: Brick oven reconstructed to a steel one

I provided the oven with what I prefer to call "Smoke sentinel". I will be using it when running the oven on wood in case the extractor fan fails. It allows the oven to breath from the lower half of the opening, and channels the exhausts through the vent. Theoretically. This thing should work. It may be needed only at start up. However. It can still be installed during the cooking if one can bear the resultant lower visibility and usability.

The tool is just a trapezoidal sheet. that touches the inner face of the outer arch of the vent, hangs by a built-in hook that engages to a wedge welded to the outer face of the outer arch of the vent. I choose to make it touch the inner side in order to prevent any smoke leaks that would be inevitable if it touched the outer side instead. The "smoke sentinel", when adjusted in place, covers half the way down from the outer arch, channeling the majority of the smoke through the vent while letting the oven breath from the rest (lower half) of the opening. I prefer to look at it as a manual engine starter in case the starter engine fails.
This is an indoor oven and I find both the extractor fan and the "smoke sentinel" crucial for the oven.
A view from the vent landing looking up 1st with, 2nd without the tool.

[v12spirit]

Re: Brick oven reconstructed to a steel one

Installing the extractor fan

[v12spirit]

Re: Brick oven reconstructed to a steel one

Ran the first test fire yesterday. I needed 8 more IFBs for the hearth, so there was a considerable space under the hearth "flying" with no insulation underneath as is clear from the pics. The ceramic blanket covered the dome in a humble way, just for the test. 90 minutes of moderate fire and the bench of semolina still not burning minutes after it was scattered on the heart (This is a primitive way for telling that the oven never saturated), and I could put my hand closed in the chamber for 10+ seconds without pain!
Am not sure if that was due to the poor insulation or to the low thermal mass.

The tool I have provided for stopping the smoke (The smoke sentinel) was amazing in forcing the majority of the smoke into the vent! The 1st pic is with and the 2nd is without the tool.

[david s]

Re: Brick oven reconstructed to a steel one

Did you determine if those bricks are dense firebrick or insulating firebrick? What is their density?

[v12spirit]

Re: Brick oven reconstructed to a steel one

Did you determine if those bricks are dense firebrick or insulating firebrick? What is their density?

They are light insulation bricks. They come in ten bricks packed in a box written on it "Insulation Bricks". I bought one box because they are not cheap, but found myself still lacking 5 at least, so there is about +-20% of the hearth not under-filled with the bricks so I tried to distribute them in a somehow fair way as you can see from the pictures of the previous post but still having spaces of up to 1" between them. I will be later filling the spaces with the cutting remains of the blanket as you suggested, but even as a test fire, I expected the oven to get quite hot. It didn't.

[david s]

Re: Brick oven reconstructed to a steel one

I think you need more thermal mass to store the heat. I'd be adding 2" thick dense firebrick to the inside of the floor. A steel floor will not suck moisture from the base of the pizza, but will trap moisture there leaving the base soggy. You need porous dense firebrick which is what gives it a crispy crunch.
I think you will also need some thermal mass over the dome as well, as has been previously advised. Your experiments are however, extremely instructive and will teach you lots about your oven.

[v12spirit]

Re: Brick oven reconstructed to a steel one

I admit that I am tempted to add some thermal mass to the oven. But seeing other steel ovens with fairly similar characteristics as mine makes me wait for a while and re-ask the question: Why did that happen?
Here is one of them:
http://www.fornobravo.com/forum/21/s...d-20370-2.html
This one has a 16 gauge steel (1.6 mm) for the dome and a blanket directly on top, mine is 2 mm (14 gauge I reckon).
The main difference is that the man provided a 1/2 inch steel plate on the bottom. I did not.
The man says his oven gets very hot that he sometimes has to wait until it slows down to the pizza cooking temps.
Why is this thus??