Debating Over Which Type of Dome

[DaveDQ]

My hearth is set and I'm ready to start my dome. I started this project with the intention of following Allan Scott's method, but now, after reading about the difference in heating times, I'm really thinking of going with the Pompeii style of dome.

The major thing I'm seeing is there is no need for all the concrete Scott suggests to use. I keep seeing these ovens with all the concrete on there and then hear some say it takes 2 1/2 hours to heat up. That's just not practical.

Can we truly say that the Pompeii will heat and retain heat in a more efficient manner?

[james]

Re: Debating Over Which Type of Dome

Scout's honor. All that concrete holds up the barrel vault, but it also wicks heat away from the inner face of the oven.

Plus, it isn't just the 2 1/2 hour heat up time. One of the most important parts of a good pizza party is keeping the inner face of the dome and floor at pizza temperature (750?F+) the entire party. You don't want the oven to start cooling down after 3 or 4 pizzas and you don't want to have to keep pushing the fire back over the cooking floor to bring it back up to pizza temperature. By wicking heat away from the inner face of the oven, that concrete makes it really difficult keeping the oven at pizza temperature.

My two cents.

FWIW -- I poured all of that concrete, and there is a lot of it. :-)

James

[Neil2]

Re: Debating Over Which Type of Dome

The "Alan Scott" method puts the insulation under the structural slab.

I don't understand this.

[asudavew]

Re: Debating Over Which Type of Dome

The "Alan Scott" method puts the insulation under the structural slab.

I don't understand this.

good for retained heat... baking bread..etc... not good for a pizza oven!

go with a dome

insulation goes on top of structural concrete... ie under the oven floor!

hard enough to heat the floor up with insulation directly underneath

[Frances]

Re: Debating Over Which Type of Dome

good for retained heat... baking bread..etc...

That is, lots and lots of bread - as in professional baker. The Pompeii is is fine for baking 10 or 20 kg of bread in one firing, and roasts, cakes, pies, whatever.

[DaveDQ]

Re: Debating Over Which Type of Dome

Thanks for the replies. I think the frustration is in the rigidness (if I can use that word) in Scott's design. Please know, I really admire some of his and Daniel Wing's philosophy in their book, so I'm not taking a shot at them. However, while reading The Bread Builders, there tends to be a little bit of a "chip on the shoulder" personality about what's the right and wrong approach to both bread and oven procedures.

It's simply that the further along I get, the more of a feeling I have that I'm building this mass of concrete, and then when I recently watched a video of a Scott oven being built, the builder mentioned "it takes a little over 2 hours to heat." I'm already regretting the concrete slab I put up for the hearth. When I see those 3 arches, covered in concrete, it just doesn't seem appropriate for what I'm trying to accomplish.

Well, I have my brick, I'm ready to start cutting and the dome will begin soon.

[DrakeRemoray]

Re: Debating Over Which Type of Dome

Many of us have worked through this same dilemma, including me...
http://www.fornobravo.com/forum/f6/m...orado-472.html

I do not think there is anything intrinsically wrong with the Alan Scott approach, rather I think it is aimed at a different audience. Scott's ovens are really for professional bakers. By professional, I mean that you want to sell bread. That is the only reason that anyone would need to do so many consecutive bakes on a single (albeit long) firing.

The pompeii design works much better for home use. Even for very serious home use. Somewhere here are threads describing my efforts at using all the heat stored in my Pompeii oven. There is way too much heat in there for my family. Off a single firing, I have cooked 14 pizzas, 25 lbs of bread, a giant pork roast, two chickens and a large pot roast. I could have done twice as much meat and half again as much bread...

Hope that helps.

Drake

[texassourdough]

Re: Debating Over Which Type of Dome

I agree totally with Drake. The Scott ovens have a different audience. The uses overlap and they can both perform reasonably as the other. The key determinant is how many batches of bread you want to make. If it is three batches of 20 pounds or kilos each, then the Scott is clearly the choice - for it can do it but it will take two to four hours to heat load before you can heat soak it an hour and then bake. A Pompei will heat load in an hour to two (depending on the amount of extra mass you have).

My oven is a Scott/FB mix in that the base is done Scott style with the insulation UNDER the cement floor. The oven is FB with an extra inch of refractory cement for mass. It will do two batches of bread and needs about two hours to fully heat load.

The advantage of the Scott design for the floor is that the extra cement keeps the floor warmer for bread because it retains extra heat. The disadvantage is that heat does seep out when doing pizzas and I have to rake the coals out and reheat the floor for about five minutes every half hour or so if I want the bottom browned. NOTE: I can do pizzas in about 45 minutes to an hour - at that point the oven is NOT fully heat loaded but with open flames in the oven the dome is fully cleared, the floor is hot and it is ready to go.

I don't have experience with the FB floor design but it should stay hotter in pizza mode. Since few actually do multiple bread batches I think the FB design is superior for most, but IF you really want to do bread, I would build a Scott - or have both a Scott and a Pompei or FB oven.

Hope this is useful to some of you debating what to do!
Jay

[DaveDQ]

Re: Debating Over Which Type of Dome

Thanks, Jay. I'm going with the Pompeii style dome. I too have the concrete mass on top of the vermiculite layer (Scott style). I did run some extra vermiculite in there, hoping it would help. I'm going to do my best to make sure the oven dome is good and insulated.

In the end, I think I moved too quickly, not checking my bases.

Journal of My Oven's Progress

[egalecki]

Re: Debating Over Which Type of Dome

Can you add a layer of vermiculite concrete on top of the hearth? See my thread for how I did mine- worked great. You could set your floor on that and then not have to heat up all that concrete when you fire the oven. 4 inches would do it. If you're worried about the finished height, mine's pretty tall for a 5'4" woman, but I like being able to see inside without having to bend over! And, if you need to, build a step in front....

If you don't separate the floor from all that concrete you'll be sorry. You could also get some insulating board- 2 inches of that would do.

[DrakeRemoray]

Re: Debating Over Which Type of Dome

I second what Elizabeth said. Stop now and insulate above that concrete mass. You could just get some insulating board if you don't want to do another concrete pour.

Drake