Designing a taller dome

[Rocko Bonaparte]

I'll be moving to a new place soon which means building a new oven. It's sad to leave the current cob/brick oven I have, but I did screw up a part of the front, among other things. Lessons learned. I had built the oven to be taller than normal because I wanted to also be able to throw roasts or dutch ovens in there. I am reminded of some of the stuff I've read on here about Greek-style ovens. But there are some good rules of thumb I tried to generally follow even when I was abandoning the recommended height for pizza or bread. However, I wondered how the rules of thumb change for nonstandard heights.

I'm thinking my next oven may be 42" diameter at the smallest inside, and we might go all the way to 56". I try to get something upwards of like a 14" front to slide the larger of my dutch ovens in and out. It occurred to me if I increased my diameter that I might just get away with making a more normal pizza oven anyways What are the recommended proportions of door height to oven height again?

I don't think I ever asked but I wondered what are the proper ratios for chimney height to oven height/diameter/whatever. Generally I was worried about the chimney. I wasn't so sure where I should have placed it and kind of just improvised its size. I was also curious about how far forward the front should extend from the dome, factoring in nonstandard heights. I would figure a long front would do some to offset this.

It might be worth another thread, but I'm curious how I might design the door into things up front. It was too much of an afterthought here, but I'd rather make it built-in or otherwise robust so I can easily do indirect cooking/smoking overnight or bake bread during the day.

[brickie in oz]

Re: Designing a taller dome

Ovens are designed to a ratio of oven door height to oven ceiling height, the ratio is .62 or 62%.
Make the oven or door as big as you want it just keep the opposite to ratio.

[shuboyje]

Re: Designing a taller dome

If it were my oven I would build it with as low a dome as possible and then build a door tall enough to fit your dutch oven. I would then build a double wall insulated metal insert that creates a smaller "standard" sized door inside of the oversized door. You could then use the insert at all times and have a functional pizza oven but remove it to fit your larger items in. A best of both worlds. If you want to cook Neapolitan pizza a hemispherical dome is already a negative aspect that you have to learn to work with, going even higher will be a real issue, especially with an oven as large as you are speaking. Going higher then hemispherical on a 42" oven is really off the charts high.

[Laku]

Re: Designing a taller dome

If you want to cook Neapolitan pizza a hemispherical dome is already a negative aspect that you have to learn to work with, going even higher will be a real issue, especially with an oven as large as you are speaking.

Don't know about higher domes, but at least hemispherical is not an issue while doing Neapolitan style pizza. At least I haven't had to do any special tricks while cooking them in my 46". Just put the pie in and take it out when it's ready after 90 seconds.

[Rocko Bonaparte]

Re: Designing a taller dome

Yeah the current tall dome I have can do Neapolitan already. It's not a problem. I suppose it can't do it for very long before needing more fire though.

[shuboyje]

Re: Designing a taller dome

Good luck with it! To each their own. It's not something I am looking to debate, but I am 100% positive I could not create the type of Neapolitan pizza I am after in an oven with a 24"+ dome.

[Tscarborough]

Re: Designing a taller dome

What exactly is the advantage of a tall dome? So long as the door is big enough to fit anticipated crockery, the goal should always be the lowest dome possible to work with that door height shouldn't it?

[brickie in oz]

Re: Designing a taller dome

the goal should always be the lowest dome possible to work with that door height shouldn't it?

I have to agree, I made my roof as low as possible to keep the heat closer to the food.

[Laku]

Re: Designing a taller dome

Maybe the difference between hemispherical and lower dome profile is that I keep the fire going on on the side while doing Neapolitan pizza and with lower dome profile you could let the fire die?

Other than that I can't imagine what's the gain, unless you're going for burnt top.

Anyway I think the topic is interesting. Logically the lower dome will get the fire closer to top of anything you cook. So it should get more heat.
How much that more is, is another matter. After all the height difference seems to be only around 2"-4" for 42" oven.

[Tscarborough]

Re: Designing a taller dome

Normally the low dome will have a 9" sailor or soldier course at the base, then dome from there, so the ceiling is even flatter. For a 42" the height would be around 15", for a Forno, 21". 6" does not seem like a lot, but it makes a fair amount of difference for cooking Neapolitan style true 60-90 second pizzas.

42" with 15" ceiling:

[Laku]

Re: Designing a taller dome

6" does not seem like a lot, but it makes a fair amount of difference for cooking Neapolitan style true 60-90 second pizzas.

Fair enough. Though I still fail to see the advantage if the cooking time is it. I can cook a pizza in 90 seconds or less in my hemispherical profile oven. In fact Neapolitan is the way that I almost always do pizza. So there doesn't seem to be that big of a difference in it?

But it might just be a case that with out having tried one it's hard to grasp the difference in it.

[Tscarborough]

Re: Designing a taller dome

I can cook a 90 second Neapolitan in my high dome barrel vault too, but I can't do it all night long, the floor cools too fast. Maybe the low dome is able to recharge the floor faster. Isn't the effectiveness of radiation the inverse of distance or something?

[Laku]

Re: Designing a taller dome

Ahhh! Ok that makes sense!

I haven't tried any big pizza parties so can't tell how long the charge would last. The most I've done is around 10 pies.

I know light dissipates in inverse square of distance, would be logical that heat does the same as it's just invisible wave length of light.

Another thing that came to mind is that hemispherical shape will concentrate the radiation much closer to its surface than less aggressive curvature. There for the lower profile will radiate less concentrated but larger area. And as the surface is closer the floor, even though less concentrated, is most likely about the same heat as the more concentrated reflection of more aggressive profile. But radiated to a larger surface area, and so heating more of the floor.

[Rocko Bonaparte]

Re: Designing a taller dome

I have some updates. I measured the height of the opening on my current oven and it's 13.5" so it's lower. If the rule of thumb is the door height is 2/3 the dome height, and I go for a larger oven, there might not need to be anything for me to do unconventionally. I'm trying out that dome measurements spreadsheet and I'm seeing something like 29" dome height for a 56" oven, and I guess I'd be looking at 18" for the opening with that. That's more than enough. I'd probably make it something like 16" in that case and have it more flat on the top. I see a lot of pictures where the openings are very round, and I see it difficult to get dutch ovens in and out that way.

[vtsteve]

Re: Designing a taller dome

What about hanging a stainless flap from hinges at the top of the door opening, so the opening/ceiling ratio is 62% when the flap is hanging down, but you can push the flap up to the ceiling for extra opening height (just when moving cookware in/out)? I've seen this in wood stoves, so you can load large chunks of wood but the smoke is contained.