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Old 06-12-2006, 10:28 AM
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Default Question about vent

Hey there,

I noticed that some ovens have vents in the front, others in the middle, and others in the rear. What are the pro's and cons to each?

Also, I noticed for most ovens, there are smoke stains on the outside which leads me to believe that the front vents aren't working well much of the time. I dislike getting smoke in my face because you can't taste the food as well if you've beeen breathing in your nose.

Any suggestions would be helpful.

Thanks,
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Old 06-12-2006, 10:47 AM
dmun's Avatar
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Default vent location

I think you will find that all brick ovens vent from the front, but the flues can be tilted to give a middle or rear chimney position, for aesthetic or clearance reasons. The conventional wisdom is that a straight vertical path is the best for chimney draw.

The only member we've heard about who is unhappy about his draw is Robert Musa, who attributes it to not having enough of a funnel shape above the door opening. I'll leave specific comments on chimney draw to those who actually have built one. In general, a taller chimney draws better.
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Old 06-12-2006, 10:50 AM
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Lightbulb Smoke escapes only on start up.

(M) Hi, Mike,

(M) I am speaking *only* from my experience which is that smoke escapes from my oven entrance only when the oven is cold and not drawing well. That is invariably when I first start my fire. An uncooperative breeze can exacerbate this problem. Once the fire is hot, I get almost no smoke period; not even out the chimney.

(M) I suspect that other bulders have had similar experiences but I've seen no postings yet supporting this probably unavoidable occurance. To mitigate it's occurance I build my starting small fire very carefully with only small, perfectly dry pieces of kindling. Even then, I will get some smoke escaping and it does discolor the front of my housing. The image I plan to post on Thursday of the front of my oven will not show the discoloration. That's because I repainted just before taking the picture. I painted the HardiPlanks a flat black (as opposed to the rest of the yellow housing) to act as a Trompe L'oile (sp?) which, from a distance, should create the illusion of a large semi-circular oven entry when in actuality, the opening is 1/2 that size.

(M) Get your kindling securely started and walk away for 10 minutes. When you come back, slowly add larger dry pieces and you should be able to bake without any smoke in your eyes.

Ciao,

Marcel
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Old 06-12-2006, 11:53 AM
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Default

A builder told me that the Naples ovens have the vent run back over the top of the dome, then straight up from the center, because the hot air of the exhaust helps keep the dome hot.

Hmmm.

I'm not sure if that is an urban legend or not, but even if it's true I don't think it's worth the extra effort.

James
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Old 06-12-2006, 03:03 PM
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not an urban legand....

http://www.pizzamaking.com/forum/ind...ic,1118.0.html

some folks are saying that the vent should hook back. So if you go this route then you want to have your refractory around this vent to force the heat down to the dome then you will want to insulate, insulate, insulate to keep it there.

Might be easier to use the flue gas as a co-gen station to heat your jacussi instead.

unless you are a member then you can't see the pics. I am not a member but when the thread was only 5 pages long I was able to get the pics...
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Old 06-12-2006, 03:36 PM
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Hey Patrick,

I know that some builders say you should do it, I think the urban legend part is whether or not it really helps.

There are zillions of wood-fired brick ovens in Italy, and an incredibly tiny percentage (that's a scientific term) of them have the vent style where you bring the chimney back over the dome. Perhaps a few thousand out of a few million brick ovens. There are a few folks out there lost in the weeds of Pizza Napoletana, who don't seem to understand how you really use a brick oven. It's too bad, because they are confusing a lot of people.

At the very most I would only consider doing this design if I were going to run a Pizza Napoletana restaurant -- and even then I wouldn't actually do it.

James
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Old 06-12-2006, 03:59 PM
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Default Mr. building code speaks

Yeah, I know, nobody follows code, but code says that flues can tilt a maximum of 30 degrees off vertical. Unlike some code rules, there's a reason for this: It's the most bend a chimney cleaning brush can navigate.
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Old 06-12-2006, 04:01 PM
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Excellent. I never knew why. Duravent only makes a 30 degree angle, and I thought had to do with draw. Now I know.
Thanks David.
James
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Old 06-13-2006, 03:30 AM
Fio Fio is offline
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Default There was a big debate on the venting issue in Pizzamaking.com

Quote:
Originally Posted by james
A builder told me that the Naples ovens have the vent run back over the top of the dome, then straight up from the center, because the hot air of the exhaust helps keep the dome hot.

Hmmm.

I'm not sure if that is an urban legend or not, but even if it's true I don't think it's worth the extra effort.

James
James,

Check out this thread. It may explain the rationale for having the vent routed over the dome, or it may just muddy the waters more. Vent Debate

The debate begins on page 7 of the thread. Look for comments written by Bill/SFNM
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  #10  
Old 06-13-2006, 08:07 AM
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"There are zillions of wood-fired brick ovens in Italy, and an incredibly tiny percentage (that's a scientific term) of them have the vent style where you bring the chimney back over the dome."

Ok everybody back away from the cool-aid. So code limits you to 30degree from vertical. I was more concerned with draft, as the drawing looked a bit fishy as the path of least resistance for the exhaust would be to spill out of the door seeking higher ground and unless you have a subtantial hood this swept back chimney seemed dubious for efficient draft capabilities.

As for a zillion and a tiny percentage lets look at Zillion. From a math research web site we get Zillion - A generic word for a very large number. The term has no well defined mathematical meaning. Conway and Guy (1996) define the nth zillion as 10^(3n+3) in the American system (million==10^6, billion==10^9, trillion==10^(12), ...) and 10^(6n) in the British system (million==10^6, billion==10^(12), trillion==10^(18), ...). Conway and Guy (1996) also define the words n-plex and n-minex for 10^n and 10^(-n), respectively.

And a Brit author says this - If your concern is only to express the hugeness of some number, without tying yourself down to anything so mundane or precise as actual numbers, you can use one or other of the hand-waving words we have in the language. Zillion ... is well-established and can be traced back at least as far as the 1940s and Damon Runyon; more recently, others have begun to appear, such as bazillion, kazillion, jillion, gazillion and squillion, hardly any of which have yet made the dictionaries, though the last two are fairly commonly encountered.

personally I would go with googolplex
Googolplex is a large number equal to 10^(10^(100)) (i.e., 1 with a googol number of 0s written after it).

The term was coined in 1938 after 9-year-old Milton Sirotta, nephew of Edward Kasner, coined the term "googol" and Kasner extended it to this larger number (Kasner 1989, pp. 20-27; Bialik 2004).

dang got off topic on this
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