New to Pompeii Oven

[WhiteRose]

We are planning to build a house, and I have been dreaming for a long time to own a hearth. My husband is almost convinced to commit on building one for me, as long as I bring him all details and specifications. I found great reviews and photos from Forno Bravo, and the free plans for Pompeii Oven made me want to embark for the journey of building one. Here are a few questions I have:
1)Are these plans suitable for a gas burner inside the cooking chamber? I hope it is not a blasphemy to talk about using gas in a wood-firing oven, but I would like to have it fired with gas because I am planning to have it inside the house (you know, trying to avoid the smoke, the black soot, etc).
2)The 40 minutes heating time is a great time that I couldn’t find in any other brick ovens out there. Is this for a 750F temperature needed to cook pizza? How long will it take to heat it at 500F? Can somebody explain what the variables that determine this heating time are?
3)Is it possible to use a glass door instead of a steel or cast-iron one? I would like to be able to see inside while cooking.
All of your input will be appreciated. Thanks.

[dmun]

Gas burners are discouraged. This isn't an open barbeque. Gas can gather within the oven, with explosive results when you try to light it. Since it's in your house, you'll need to get building code approval for your oven, and no one will approve a gas appliance that's not to code. You could get a commercial oven with a gas burner, I think FB sells some of those units, but because of the extreme safety requirements, they are MUCH more expensive than wood burning units.

The forty minute heat-up time is for the pre-cast refractory ovens, which are thinner than the ovens we build here. And again, that's with a wood fire which produces raging heat, I'd be alarmed about the amount of BTU's a gas jet would need to produce to heat up a brick oven in fourty minutes. We're talking about a lot of mass here.

The ovens that leak smoke are outdoor ovens. They typically have two or four foot chimneys, and don't have enough draw, since the bottom of the chimney is more or less the same temperature as the top. They are also subject to gusts of wind. An indoor oven with a chimney tall enough to get two feet above your roof will draw, as Jim says, like a locomotive.

You can use unlimited creativity in building your door. Since the door isn't used except after the fire is raked out, there's not much to see inside, but some builders have installed lighting in the entry, in which case a glass door might make sense.

Temperature control is something of a learned art. In most cases, we fire the oven to pizza temperature, and if we need lower temperatures, we wait until the oven cools off.

One final thing. With an indoor oven you are going to want a damper in the flue, to close it off when you aren't firing, so you don't loose heat in the house. Good luck with your project.

[james]

Here is the standard response I have written up on gas burners in home ovens. As David says, we strong recommend against them for both safety and cooking reasons. The burner than comes with the Modena G oven is a real monster, and is not appropriate for home use. It's scary up close and personal.

I think wood-fired ovens for the home are great -- definitely the best way to go.

Here's the stock response.

********

I am sending you background information on our ovens that I hope will be helpful. We do not recommend gas fired ovens for homeowners for two reasons. First, there are some serious safety issues. Pizza ovens are small and enclosed and even a small leak can leave enough gas in an oven to be unsafe and capable of exploding. Our commercial gas-fired ovens have very sophisticated burners that cost $3,000 by themselves, and are operated in a commercial setting by professionals.

Second, a gas fire has much less potential energy than a wood fire, so gas-fired ovens take a long time to heat up from scratch. Gas does a good job of holding a commercial oven at cooking temperature because those ovens never fully cool down. Still, it can take hours for a gas burner to heat up an oven from a cold start -- which is what homeowners do with their ovens. The Forno Bravo wood-fired ovens heat up in about 45 minutes, which is why they are so popular.

Again, I hope this is helpful.

[asudavew]

Originally Posted by james

The Forno Bravo wood-fired ovens heat up in about 45 minutes, which is why they are so popular.

I gotta get me one of those!


One of these days!

[james]

Dave,

You have an FB oven. :-)

James

[WhiteRose]

Thank you for all the answers.
From what I read throughout this forum, most people have these wood-fire ovens outside. Is it even safe to have one inside? Besides a tall chimney I will have to have, are there any other considerations I should think about?

James,
1) How do I judge the size of the oven I need? You say that the difference in cost and effort of building a 36” oven is not much, compared to a 32” one. But, won’t I use more wood to fire and wait more time to heat the 36” one?
2)Some recommend considering cooking based on the heating retention time not on the oven floor dimension. What do you think? Then, will a 24” (internal) oven be enough to cook several pizzas (even one at a time) with a difference of a couple of minutes between them? I am confused.
3) Then, adding some extra thermal mass in the floor will make sense for a smaller oven, to help you cook for a longer time at high temperatures? How much more is this extra mass going to increase the overall heating time of the oven?

David,
1)you say: ” The forty minute heat-up time is for the pre-cast refractory ovens”. Do you know how much will it take to heat-up one of the Pompeii ovens with a 32” internal, to 500F? How much wood do I need to accomplish this temperature?
2)Thanks for reassuring me about the possibility of a glass door. Now, if the door is used only after the fire is raked out, I was wondering if the heat from the fire won’t escape in the kitchen. It shouldn’t be a problem during the winter, but in the summer it is going to be detrimental, isn’t it?
3)How do you cook in these ovens: with the wood burning in, after it has burnt but keep the coals inside, or rake them out then put the pizza inside?
Thanks for trying to enlighten a dummy.

[gjbingham]

Re: questions to Dave -
1) every oven is different, based on the type of brick you end up with, the insulation used, the wood you're burning...on and on. I think a 36 inch oven is a great size. A 32 incher - you'll probably end up cooking one pizza at a time, or two small ones. You pretty much want to get the oven to 750ish and let it cool to 500. If you stop after 30 minutes of fire, the oven will be at 500 degrees (possibly), but quickly cool to 400 or below, because the bricks faces got hot, but the entire bricks were not up to temp, so they cannot maintain the original heat that you measured.
2) Most of the heat goes up the chimney. A good door can help direct that heat trying to get out the front up the chimney as well. Regardless, you'll probably have some residual heat sneaking into your already hot house in the summer.
3) Pizzas cook with fire burning. Breads and other foods, the fire's out. There's plenty of people cooking at lower temps though with small fires burning. You make your own decisions. Its your oven and your food.

[james]

All good questions. Let's see if I can get them all.

1. From a time perspective, you can get a small to mid-size FB Casa oven up to 750+F in about 45 mintes. You shouldn't always force it, and giving the oven time to absorb heat is a good thing for longer cooking periods. Still, in a pinch, you can do it. The company that makes the Casa and Premio has their own refractory "recipe" which is really part of their crown jewels for fast heat up and good heat retention.

2. On size, you shouldn't go smaller than 31". I've said this before, but I installed and used a 26.5" oven for a year, and it just didn't work. The opening was too large relative to the oven size, so it gave up heat too quickly, and there really wasn't room for anything to cook when you had a fire burning. 31" is good, and 35" is better. If you really like to cook, 39"-43" give you a lot of space for work with.

3. Heat up times and heat retention times change within the 31"-43" range, but not by a huge amount. A larger oven will take longer to heat up, but perhaps 15 minutes more; and it will retain heat better. Still, the 31"-35" oven will easily retain enough heat to roast a turkey or bake lots of bread.

4. You definitely do not want to add more mass under the floor unless you want to do multiple bread bakes per firing. I think that keeping the floor hot for pizza baking is one the biggest challenges to operating a wood-fired oven. The floor seems to give up first.

Why don't you read around some in the forum -- perhaps typing in term into the search function. There is a lot of collective wisdom here.

Keep the questions coming.
James

[WhiteRose]

Ok, the fog is clearing bit by bit. Thank you for clarifying things for me.
I will take James’s advice and read through the forum. You know the old saying: The more you learn, the less you know. After reading and trying to learn about brick ovens, I realize how little I know about its principles and basic functions. But, I will continue to do my homework, and I will submit the project to my husband for "approval"

[gjbingham]

James,
in reference to your answer number 4) above, I'm curious if the modular ovens have difficulties retaining floor heat like our brick-built versions.

Thanks!