lowering cooking floor temp (at building time)

[mikeyr]

 I am in the final stages of putting together my oven, I have borrowed the manufacturers oven that is on a trailer while I was building mine and I find the cooking floor to be too hot.    They recommend vermicrete or board insulation directly under the cooking floor, the cooking floor is high alumina content tiles.  I think its too hot and it burns the bottoms of my pizzas long before its cooked.  I am thinking of adding some bricks on top of the insulation but under the cooking floor as I pour the insulation, my thinking is that will add some mass to the floor and yes it will stay hot longer with mass but it might cool it a little by giving the heat somewhere to go.  The builder does not recommend that by the way and says you put the pizza on the floor and after 30 seconds lift it up and hold it in the top half of the oven and let the top cook.  I don't like that technique, I never had a problem at my old house with my Mugnaini but that oven was too small.

 Looking for suggestions to cool the cooking floor while I am still in building stages.  I am putting together a pre-fab brick oven, not building from scratch.

[Tscarborough]

It sounds like a lack of mass in the dome, not the floor.

[scott123]

How high alumina?

As the alumina goes up, so goes the conductivity/heat transfer.  The extra thermal mass on the floor will use up more wood, but regular firebrick splits should give you more traditional/less extreme bake times.

[mikeyr]

I think its 70% alumina and the dome is split bricks so 4" thick plus a layer of concrete (not sure how thick) then lots of insulation I would  think plenty of mass in the dome.

[scott123]

If they are 70% alumina, then that's really high.

I just re-read your post and noticed that you're thinking of putting something underneath the tiles.  My advice is to lose the tiles completely and go with a traditional firebrick (full size brick) floor.

[ThatsAmore]

I thought most here was against using Aluminum and Galvanized inside ovens?

[scott123]

ThatsAmore, alumina (Aluminum oxide) and aluminum are two different things.  Alumina is a standard ingredient in firebricks.

[ThatsAmore]

Aluminum is Aluminum ... it's an element ... reduced to it's simplest form ... Being oxidation of Aluminum (rust), still is Aluminum, just oxygen rich.

[buceriasdon]

The chance of free alumina being released is near impossible. The alumina and silica are partly vitrified in very high heat kilns causing the molecules to fuse together, therefore making the firebrick very inert.
Don

[Polo]

Aluminum metal is a product of alumina, not the other way around. Alumina itself has a melting point of around 3,600 degrees Fahrenheit, hence it's use in refractory products.

[ThatsAmore]

I stand corrected 

[mikeyr]

If they are 70% alumina, then that's really high.

I just re-read your post and noticed that you're thinking of putting something underneath the tiles.  My advice is to lose the tiles completely and go with a traditional firebrick (full size brick) floor.

 That may be my best choice so far, one of those "duh, why didn't I think of that?" answers...Thank You!

[mikeyr]

 just for the record and to complete this post.  I finished my oven and have been using it A LOT, burned some pizza's and had some great ones too.  I ended up putting the oven floor directly on vermiculite mixed with little cement, works great.  The oven I had used prior to mine had the floor directly on concrete, this vermicrete is working great.