dome height reduction test

[thezaman]

i am trying to see what effect a lower dome heist would have on my premavera 70 . had my floor covered with a 28 inch fire brick insert. this brought my dome down from 13.5 inches to 12 1/4 inches. i want to see if the pizza cooks more balanced. enclosed are pics

[KraemerBAC]

Re: dome height reduction test

Have you decided yet or is more testing needed??? That looks like a pretty fine pizza to me

Peter

[thezaman]

Re: dome height reduction test

the primevera cooks a really good pizza.i am going to leave this setup all summer to see if there is a difference in performance.

[Glosta]

Re: dome height reduction test

Z-man: I am interested in your findings? Did lowering the dome height result in any significant performance change. I am building a 42 inch Pompeii with 20 x12 entry.

I am on the sixth chain & the curve seems to be developing slowly leading me to believe I may wind up with a 24 inch interior dome height. Will this pose a problem? Why. I have seen the door to height ratio often recommended to be .63. Why? Has any body actually tested or is this repeated urban folk lore. The FB construction manual states you should have the door height to dome height ration greater than .63 so you don't lose all your heat up the stack. It also states that many Italian WFO have high interior domes. Have you seen any actual performance data or had input from any reliable authority on the effects of hiagher arched domes. Input from anyone would be greatly appreciated. Thank you. Glosta.

[shuboyje]

Re: dome height reduction test

Somebody already touched on this in another thread...but I'm gonna repeat it because you are setting of some major red flags. What are you using to control the shape of your arch? You really need to plan on a dome height first, which will then control your door height(or if for some reason the door height matters go that way...but that seems backwards to me).

To answer your question, to the best of my understanding the 63% door height was determined by a study done on the bread ovens of Quebec which found that to be the ratio of the best performing ovens. The height of the door helps to control the heat of the oven. Too high and too little heat will be given to the dome before it exits... too low and you will not have enough airflow to fuel your fire. You could go lower but there is no need to. Wood fired kilns are built with flues at the very bottom to reach ridiculously high temperatures, but they have huge fire boxes and very tall stacks to generate the airflow needed... not worth it if you don't need to get that hot.

[Glosta]

Re: dome height reduction test

Thank you for the quick reply. Yes I am trying to conform with the FB Tuscan oven specs. I am building a 42" Pompeii & using an I-tool. My door arch came out 12 inches by 20 (I was shooting for 12.5) I am just concerned the curve seems to be coming too slow to reach the 22 height recommended. Increased the pitch 100% this morning 3/8inch to 3/4 inch. Looks like the cure. Plan to cut a 1 inch angle of the front of the next chain to accelerate turn. Thank you again.

[BurntFingers]

Re: dome height reduction test

I was reading these posts and recall that in Wing & Scott's book, The Bread Builders they recommend a 63% height ratio door to inner dome. The example they gave is 16" inner dome.

I took a picture of an oven recently when we toured the excavation in Pompeii. It was however a commercial oven. My hand is in the area for the smoke to rise up the chimney. Unfortunately I didn't have a tape measure with me. The inner dome height was about the same as the outer arch and the width of the oven was about the same as the width of the arch.

[thezaman]

Re: dome height reduction test

i cut my dome height by 1.5 inches and i feel it cooks a much better pizza. the balance is better and the top heat is lower over the pizza . i do not have to dome my pizza to cook the top. i think i get better oven spring as well. my change was minor i don't think that the door size affected it much. your situation s different . if pizza is your main interest the dome height makes a difference. enclosed are two pies from monday.

[PizzaPolice]

Re: dome height reduction test

I took a picture of an oven recently when we toured the excavation in Pompeii.

I used that oven for my Avatar/Logo.

[BackyardPermaculture]

Re: dome height reduction test

thezaman, those pizzas look great!
Cheers,
Mick

[Neil2]

Re: dome height reduction test

"to the best of my understanding the 63% door height was determined by a study done on the bread ovens of Quebec"

You will find much the same ratio in many of the traditional pizza ovens in Italy, Sicily and Croatia.

[james]

Re: dome height reduction test

Hi guys,

I think the 63% door height to oven dome height is one of those urban legends, where if it keeps getting repeated enough times it becomes fact.

Oven dome to oven door height depends on the type of oven you are talking about. There is a large, mainstream Italian wood oven manufacturer based on outside of Rome who makes a "traditional" oven with a 47.3" floor, 22.7" dome and 11.8" door opening.

The dome is 48% of the floor diameter (a little less than the radius) and the oven opening is 52% of the dome.

I think they would be really surprised if someone told them that a Quebec bread oven was more authentic than their Italian wood oven.

Equally, our 47.3" Modena oven has a 16.5" high dome and 10.6 high oven opening -- which are 37% of the floor diameter and 64% of the oven dome height.

These are two very different ovens, both made in Italy.

I think the most interesting point is that there is no one "right" oven design. The high and low dome ovens each have their own strength. It's also interesting to point out that I don't think that the great people in Quebec were trying to make Pizza Napoletana 100 years ago.

For DIY brick oven builders -- I think you can relax and not stress an inch or two here or there (within reason). :-)

James

[fxpose]

Re: dome height reduction test

For DIY brick oven builders -- I think you can relax and not stress an inch or two here or there (within reason). :-)

Thanks James, I agree.
I think I stressed over my entry height during my build and ended up with about 60%. I agree there are several variables like dome shape, dome volume, entry shape, etc.......but at the end if your entry and dome look about right against each other the oven is probably good for the most part and you'll be happy with it.

My 60% entry is non-arched and is rectangular. I think my oven may behave differently if instead it had a 60% arched entry as the arch can choke off more hot gasses from escaping at the corners and into the flue. Who knows...? I can always add a sheet metal arch without altering the 60% ratio and see what happens......maybe my oven will each operating temp quicker....

George

[sjmeff]

Re: dome height reduction test

Thezaman - how much more time does it take to get to pizza temps with the additional 1.5"?

S