Oven floor design: thickness & insulation

[RTflorida]

James, good point about keeping a good fire going throughout your pizza bakes; I always have, but lately I have kept a bigger fire (basically because my current batch of logs are larger). On a couple of my earliest multiple pizza bakes, I had to do exactly as you mention - pull the coals back over the cleared area to recharge.
Another point I've learned - letting my oven "charge" a little longer after it burns white. Initially, I waited 10-15 minutes; now I go about 20. No more issues (as of late) with the hearth cooling down before all of the pizzas are done.

RT

[gjbingham]

Great thread!

Dmun says heat rises. I think statement is entirely correct wrt heat in air. My oven's stand gets warm by the next day, so heat certainly sinks towards cooler areas as well. Ever sit on a big cold rock? It's not the rock that makes your butt cold, but the fact that heat flows from warm to cold, and you actually loose heat to the rock, and your butt gets cold.
In a well insulated and closed oven, the heat has to go somewhere, otherwise the oven would stay hot for eternity. While I didn't build a perfectly thermodynamically perfect oven, I'm still not happy with the way the oven floor cools so much faster than the dome. I'll keep working on moving my fire to the side so that it keeps burning hot. Seems like when I move it over and add a log, it burns hot for about 10 minutes then afterward, is really hard to keep the fire going really hot. Probably just poor oven management.
Comments, recommendations? As I said, gread thread! Thanks!

[james]

Hey George,

You should be able to add a smallish piece (2-3") of wood every 15-20 minutes, and have it combust pretty much on impact. That way you add flame and heat, without damping the fire until the new piece catches.

What do you think? A bigger fire? Of perhaps slightly smaller wood, so that it is ready to catch fire? More aged wood that is ready to catch?

Good thread.
James

[RTflorida]

Keeping a bigger fire (not huge or scary) has been a big help to me. I started out letting my fires die down too much ,I think. I've never had issues with logs catching once I 've reached the high temps, they DO catch almost instantly. My problem was not keeping at least one good, fresh log on the fire...doing so has made a big difference recently.
I would also like to add, if you have the opportunity to get your hands on some seasoned citrus, jump on it. There is a pretty big learning curve because it burns so long and hot (my first fire I thought the whole oven was going to melt), but my wood consumption is literally 1/2 of what it is when I use oak or hickory. Maybe the citrus is the reason I am having no problems with hearth temps dropping after several pizzas...probably a combination of the changes I've made, I'm not sure.

RT

[Xabia Jim]

Originally Posted by RTflorida

I would also like to add, if you have the opportunity to get your hands on some seasoned citrus, jump on it. There is a pretty big learning curve because it burns so long and hot
RT

Interesting, my spanish friends told me the best wood for Paella was orange wood....I'll need to try that!

[Xabia Jim]

Originally Posted by gjbingham

Great thread!

Dmun says heat rises. I think statement is entirely coorect wrt heat in air. My oven's stand gets warm by the next day, so heat certainly sinks towards cooler areas as well. !

Cold is the absence of heat...I notice that any of the masonry in touch with the oven eventually warms up as it wicks away heat. (particularly after 5 days cooking)

My first oven was to be a cooking oven and the thermal mass was intentional....but after the FB addiction "I want Pitha"

[vincent]

Although i haven't built my oven yet i believe that i can give a bit of advise on a hot fire. My wife and i cook most of the winter with a 1936 Kalamazoo wood fired stove. The fire box is very small. Its easy to get the cast iron top hot but the oven is different. It requires a hotter and constant burn. I buy my firewood split and delivered which i then have to split it even smaller. Its generally oak or ash which burns very hot. When i want increased oven temps i use pieces that are only about 2 inches in thickness. i also use a small axe to shave off the bark. There isn't really any BTU value in it and if the wood is stored outside it has a tendency to wick moisture. Its worthless and slows the fire down. I have found that feeding the fire in this manner the oven temp quicky increases and becomes easily maintained. One last thing. Properly seasoned wood is critical.

[james]

Originally Posted by vincent

... I buy my firewood split and delivered which i then have to split it even smaller. Its generally oak or ash which burns very hot. When i want increased oven temps i use pieces that are only about 2 inches in thickness. i also use a small axe to shave off the bark. There isn't really any BTU value in it and if the wood is stored outside it has a tendency to wick moisture. Its worthless and slows the fire down. I have found that feeding the fire in this manner the oven temp quicky increases and becomes easily maintained. One last thing. Properly seasoned wood is critical.

This is excellent, excellent advice. Right on target -- and what a difference it makes when you do it right.

Maybe we should move some of these postings to Fire Management.
James

[gjbingham]

Good post Vincent!

I did 9 pizzas tonight. The party was delayed by an hour - the oven heated for 2 full hours. The heat retention is much better, in fact, overly so. Four hours later I was still waiting for cooler temps to put Kaiser rolls in the oven.

The pizza was superb tonight. Good comments all!

XJ - think of heat as simple energy. It takes energy (read - fire in this case) to make the sustrate (oven) hot, and subsequently colder surfaces around it absorb it. It runs downhill like water, higer energy to lower energy, hot to cold. Never cold to hot. Hence, you get a cold butt on a cold rock!

[Xabia Jim]

I'm with you george.....but I do prefer the hot butt from the hot rocks under the sun!