Bigger ovens

[dmun]

Re: Bigger ovens

Or no flue as the oven is outside?

First, congratulations on your decision to put your flue in the front. It's the proven technology, and will make for a better oven.

You do want a chimney in the oven. At start-up your oven will produce a lot of smoke, and that's when you have to do most of the face-to-oven work of building the fire. You can build an oven with no flue, but you will have a lot of smoke in your face, and the front of your oven will be covered with soot.

In addition, the flue will improve air-flow, and will get your fire going more quickly with less frustration. That's why serious boilers have tall chimneys: the draft supercharges the firebox.

[CanuckJim]

Re: Bigger ovens

Guys,

Years ago, a friend of mine purchased an 1820 square cut limestone farmhouse north of Kingston, Ontario. It's a lovely building, but it was in need of lots of masonry repair work. (No matter what, it remained a refrigerator in winter.) Part of the work was to restore a limestone beehive oven that had fallen in. Most of it projected from the outside wall. It shared a flue with the six foot wide cooking fireplace next door, and the flue was in the front but not isolated from the bake chamber. The limestone construction blocks were an average of six inches thick. It WAS possible to get it up to baking heat, but not for long, and it took enormous amounts of wood to get there in the first place.

Ruth, the lady who did the baking in it, was a dedicated historian and definite believer in the old ways. That didn't keep her from cursing the design. She ended up not using it very often, mostly around Christmas.

Jim

[Dutchoven]

Re: Bigger ovens

I think you will be happy with it and will have a very efficient and long standing oven!
Dutch

[JayP]

Re: Bigger ovens

After looking at squirrel tail ovens I have decided that I don?t want to put the flue at the back. Our oven will no longer have a hole in the back, thank you for correcting my misdirection. I will post a design with the flue at the front when I have designed it. Or no flue as the oven is outside? Will search the forum, thanks again!

[edschmidt]

Re: Bigger ovens

And gas indoor ovens pretty much killed wood fired outdoor ovens as well, I guess were all just living in the past and need to keep up with technology. My point on the 50-100 years is that they did this for generations AFTER having full knowledge of the roman design. It must have done something better for it to be built that long. My guess is that it heated quicker, but probably lost heat quicker as well, but before highly efficient insulation it was probably not that significant.

[gjbingham]

Re: Bigger ovens

Edschmidt,
50 - 100 years seems hardly a proven design compared to say a couple of thousand years of use of the oven provided on this site. There's nothing wrong with experimenting with existing or new designs, they might be better. If they proved to be significantly better, no one would be using the older designs at all. At least, that's how I see it.

Man dreams, builds, modifies, then discards those ideas that don't work as well as their existing model. You can make even a poorly designed model work, (my oven for example), but no one would do it that way again for very long, say.... 50 - 100 years?

Another devil's advocate, back at ya!

[Dutchoven]

Re: Bigger ovens

Ed
You are correct in saying many "squirrel tail" ovens vented from the back and then over the dome. I do not however recall the one that the MHA folks built, I would love to see it! I believe that there are ways to create something that would satisfy both needs...I think if the opening to the flue is at the recommended door height and is located correctly I think such an oven could heat up in good time...however...keeping the heat in would be another issue as you have added an additional "drain to the bathtub"...one opening to the oven is simpler and more efficient...has to be...
That's my 2 cents before bed...
Jealous about the Labatt's...have not had one sine I left NY!
Dutch

[edschmidt]

Re: Bigger ovens

I love being the devils advocate.....So..... I believe the squirell tail ovens which from my knowledge were built in vermont and other earlier settlements had the flue in the back.

People seem to quickly dismiss this change by saying it was less efficient, but if that was the case why did they do it for 50-100years. It seems to be more laborous to build, so it must have served a purpose right? I know at least one of the ovens built by the MHA (masonary heaters of america) was a squirell tail design. It would seem that giving the exhaust gas a second pass at the masonary would make sence (scents? im on my third labatts). I think there is a way to make an oven in this manner with high tech insulation and have the best of both worlds.

I believe alan scott wrote that domed ovens are old technology which should be relegated to history. I just dont feel comfortable dismissing the squirell tail (or the dome for that matter) as easily.

[james]

Re: Bigger ovens

Hey David,

I think this is the second time we answered the same question the same way; at the same time.

Great minds....

James

[james]

Re: Bigger ovens

Hi Jay,

There is a style of Italian oven where the vent is located outside of the oven chamber above the door, where it arches back over the oven dome -- and connects to the chimney at the top of the oven. While it looks as though it could be vented in the back, it is the same oven design we describe in the Pompeii Oven e-book.

The Twin Ovens were actually made in Italy, and shipped to NY -- where they use Caputo flour. :-)

The main advantages of the Italian design is that you have much better control of the fire, higher heat cooking and better use of your wood.

Community wood-fired ovens are the wave of the future.
James

[dmun]

Re: Bigger ovens

The ovens you linked to:



are the twin ovens at "a mano" here in Ridgewood NJ. Those are low dome Naples style ovens, and yes the vent is above the door. The commercial builders of this style of oven angle the vents up from the entryway and take the vent stack up from the center of the dome enclosure. I think this is mostly for aesthetics, but do not be deceived: these DO NOT vent from the inside of the dome, they only look that way.

We've only seen one built example of an vent-from-the-dome oven, built by the father of a member (can anyone help me with a link here?) that wasted vast amounts of fuel, and took forever to heat up. No amount of dampering is going to compensate for having the flue in the wrong place. One additional thing about wood stove commercial dampers: they are designed to cut off only about 80 per cent of air flow when fully closed for safety reasons, and they are just a flap of cast iron - no insulation at all.

Ovens are a lot of work to build, and we're here to help you to build one that will work right the first time. If you decide to do things differently, we're here to cheer you on, and to learn from your mistakes, or to share in your triumphs.

[JayP]

Re: Bigger ovens

Thank you for all the feedback, our pizza oven will be the better for it!

My flue has received the most attention and I would like to explain why I designed a pizza oven with a rear flue and how I believe they work.

The advantages of putting the flue at the back:
? The oven will be easier and cheaper for us to build because we won?t need a hood over the door and can simply put the flue straight into the oven.
? We get our door opening directly onto the cooking floor, an advantage I think that is more applicable to bigger ovens. We would need to be able to reach 1.75m across the floor plus an extra length for the flue, using a 2m plus pizza peel.
? And well?the oven just looks more approachable (see perspective).

How a pizza oven with a low rear flue with damper would work:
? The cook would be able to tune the damper so that the flue draws enough to stop the oven from smoking out of the front, but not enough to suck the hot gases from the dome. To do this you would simply close the flue until the oven starts to smoke from the front, then open it a bit.
? The cook can also choose to shut the flu off which means the oven work like ovens displayed on this site, and vents from the front.
? Using a door you would be able to shut the oven down and retain the heat. You also have the option of shutting the flue.

Perspective @ http://www.fornobravo.com/forum/phot...dex.php?n=1028
Pictures of pizza ovens with the flue at the back - http://www.fornobravo.com/forum/f37/....html#post8640

If the oven will not work like this why not, and has anyone used an oven with a flue design similar to the one I have posted, or the ones in the above link?

Thankyou
Jay

[CanuckJim]

Re: Bigger ovens

Jay,

I built my own Alan Scott 4'x3', brick by brick, barrel vault oven for baking bread. From my experience with this build and also installing Forno Bravo ovens for customers, I would very strongly suggest that you completely scrap the idea of the flue placement at the back. This simply will not work with any efficiency. Making the oven more accessible is a misdirection; properly built these ovens do not smoke, and the facade of the chimney will only get warm to the touch. The whole point about these ovens is to get them hot and keep them hot. For a community oven, this would be crucial for people who want retained heat for bread, meats, casseroles. The design you suggest would guarantee, damper or not, that most of the heat would go right up the flue. Stick with the flue in the front model; it's been proven over centuries. True, for you fuel is not an issue, but how long are you willing to wait to get the oven up to heat? With a rear flue, you'll be stoking and waiting quite a bit; then add gathering and cutting into the equation. The time would be better spent baking with a beer in hand.

The 63 per cent figure for door height is the one to go with. I'd use the dimensions of one of the Ristorante ovens or go with a barrel vault design. My oven is a demon for bread baking, but it's not as efficient for pizza, though it can be done with practice.

Also, the mantra here, and it's a tried and true one, is that you can NEVER have too much insulation, both below and above. I suspect you'll only want to build this oven once, so insulate it as thickly as you have room for; you'll be glad you did.

I suggest you revise your drawing and re-post it here. You will get the advice you're after.

Jim

[Dutchoven]

Re: Bigger ovens

Jay
Just realized this when I read your last post, although you said it in the first I just didn't recognize it...about the flue in the back...I think you would have to make the opening to the flue at the 63% height and the door should be lower(I think) otherwise your exhaust gases will exit the door. I agree with Dmun and think you should use the door as the "exit" for the gases...you could then run the flue over the oven dome toward the center or the back...that could be the best of both worlds!!! I will try to render up a sketch for you tomorrow!
Dutch

[james]

Re: Bigger ovens

I think a community oven is a great idea. It reaches back to a time when the oven was the center of the community for bread, cooking, and events; and the gatherings and the food will be great. We have talked about wood-fired ovens supporting community work before.

I would agree with the idea that you should build an oven where the vent is located outside the oven chamber, above the door. It will be easier to manage heat and temperature, it will be better a baking pizza, and more efficient with your wood.

From the perspective of dimensions, check out the FB Ristorante ovens. They go all the way up to 185 cm (nearly two meters). This type and size of oven is used throughout Italy to support large restaurants. My view is that these proportions will work well for both high-heat cooking, such as pizza, and for retained heat cooking, such as bread and roasts for the community. You are in good company here. These restaurants make pizza all day, and then bake bread the next morning.

Here is a link to the oven sizes. The drawings give you floor, dome height, door width and door height sizes.

http://www.fornobravo.com/commercial_pizza_oven/pizza_oven_specs/ristorante185.html

Let us know how the project goes.