Driving heat across the cooking floor

[Xabia Jim]

Re: Driving heat across the cooking floor

We did a dozen pizzas last night.....roasting and breads today!

I moved the fire across the floor before pizza time so I'd have a good hot hearth. One large log (6-7 inch) was left and I used three smaller branches (2-3 inch) during the pizza's for the fire across the dome. The pizzas were done in 4 waves of 3 with pretty consistent results.

My oven is more of a bake oven with a large thermal mass so I think my hearth temp is more constant. I'll check with the gun next time as I rotate pizzas to check actual temp drop.

Just refiring this morning and the oven is still 350 degrees. In go the chickens!

[Alan]

I provide these comments without the benefit of direct experience - our first pizza is scheduled for tonight! - but with some knowledge of heat transfer...

"Recharge" of the floor should certainly be accelerated by the fire, but if the oven has reached equilibrium as shown in James' cartoon in the first post, the surface should also re-charge from heat spreading back from the depth of the floor. In other words, as soon as the surface cools due to heat transferred to the pizza, the surface will be cooler than the deeper portions of the floor and stored heat will move back toward the surface.

Anyone who has an infrared thermometer and a thermocouple at some depth into the floor should see the surface temp down a little after the pie is removed, and, of the fire is down, the surface temp recovering at the expense of a drop in temp at the "depths," followed by the two temperatures moving toward each other.

As others have discussed throughout the site in determining material choices, there's a balance between thermal mass that provides heat storage and thermal conductivity that allows stored heat to promptly become available for cooking.

[jayjay]

cooking temp?

I guess you folks are speaking of logs and we are speaking of sticks.
I am wondering what size 'logs' you folks put into your oven when you are
firing it to make bread or pizza.
I have posted below regarding the size dementions of the oven and its
basic construction.
If your will give me information, I would greatly appreciate
what is sent. You can also email me at
pugoclaire@yahoo.com
if you would like to get or give a faster responce.
Thanks,
JJ
Philippines

[james]

I have heard a number of people say that keep the cooking floor hot while cooking a number of pizzas in a row can be a challenge. We did an experiment with a Casa90 yesterday that was a good learning experience.

We fired the oven very well (over 90 minutes, and a pre-heat the night before), so it was hot and dry. pushed the fire to the side, and let the flame drop. The dome was well over 800F and the floor was around 750F. I then cooked two pizzas. The flame had almost completely gone down, though there was a big bed of coals.

After the two pizza, the floor had fallen to about 625F. I am guessing this is what a lot of people have seen. At this point, it would be increasingly difficult to make a great pizza.

I add two pieces of wanlut (about 4" diameter and 8" long). They caught fire very qucikly and burst back into flame, which reached about half way across the dome. Within a few minutes, the floor was back up to 750F. You could feel the fire driving heat across the floor.

The next pizzas were great.

While it is obvious that the fire is important for bouncing heat down on the top of the pizza, and recharging the heat in the dome -- it is even more important in keeping the cooking floor at good cooking temerature.

Salute.
James