#1  
Old 10-29-2008, 10:34 AM
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Location: Minneapolis
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Default Offset Chimney

Hello,
I am just finishing up the dome for the oven that I am building and I have a couple of questions. I have been building the oven according to the "Bread Builders" book. I am wondering if it is possible to have the chimney offset from the doorway. I understand that the gasses need to move quickly out of the doorway to create the proper draw. I intend on using a eight inch pipe for a vent and plan on having the chimney about eight feet tall. I would like to have the chimney at the front corner of the oven about 27" center to center. This is for aesthetic reasons. How can I make this happen?

My other question is where is the best place to position a thermocouple in the oven. THis oven will be used for bread and for pizzas.
Thanks
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  #2  
Old 10-30-2008, 04:19 AM
staestc's Avatar
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Default Re: Offset Chimney

Your flue needs to start directly above and in front of the door. I see no reason why you could not angle from there towards the corner, then go up from there, but a steep angle might slow down the length of time it takes for the flue to heat up and start working properly. I would think you might have smoke rolling out the door for a bit until the flue heated up enough to start drawing properly.

Just my two bits,
Travis
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  #3  
Old 10-31-2008, 09:00 AM
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Default Re: Offset Chimney

This is currently what I am thinking for the design of the flue and smoke box. I would appreciate any info about the feasibility of this design. I am a pretty good welder and plan on welding the smoke box. Does it matter if the flue is based off to the side of the smokebox? does it need to be directly above the smoke box?
Here are some photos of the setting of the oven and the current progress
Attached Thumbnails
Offset Chimney-yard.jpg   Offset Chimney-oven.jpg   Offset Chimney-oven2.jpg   Offset Chimney-yard2.jpg  
Attached Files
File Type: pdf oven.pdf (170.4 KB, 252 views)
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  #4  
Old 10-31-2008, 03:11 PM
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Location: Washington State USA
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Default Re: Offset Chimney

Here's a thought and I only toss it out since you said you were a welder: Fabricate a hood such that the gasses escaping from the left hand side of the entrance door move up at an angle to the right. Perhaps that's not clear, on your drawing the top line of the cross section of the chimney makes a dog leg, instead make it a straight line from the top left to the actual connection to the vertical chimney. You could build the whole thing out of ten guage plate; front and back plate and constant width strip to separate them. Probably be easier to build. Your drawing has the whole assembly covered by stone so it wouldn't be any more visible than what you have.

The advantage of what I'm suggesting is that the gasses don't have to move horizontally before they start moving upward.
Bests,
Wiley

Last edited by Wiley; 11-01-2008 at 12:00 AM.
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  #5  
Old 10-31-2008, 03:29 PM
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Default Re: Offset Chimney

That sounds like a pretty good idea. Anyone have any thoughts about this or have any other ideas?
Thanks
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  #6  
Old 10-31-2008, 03:53 PM
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Default Re: Offset Chimney

It looks like your oven is attached to the house, meaning that your oven may have to conform to code. Code is pretty clear, you can have two bends in your flue, not to exceed thirty degrees, in order to offset the chimney top from the firebox. Horizontal runs are not allowed because you can't get a chimney brush down them. You'll have to also maintain close attention to "clearance to combustibles". You can read the IRC pertaining to masonry fireplaces (the code applying to brick ovens in residences) at rumford.com
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Old 10-31-2008, 08:52 PM
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Default Re: Offset Chimney

The oven is not attached to the home. I looked into the code before construction. It needs to be 2" away from any structure and the chimney output needs to be 3' above anything within 10'. It will be with the chimney offset to the corner of the oven. The code is not so clear for the chimney elbows as far as a outdoor fireplace is concerned. Is it necessary to be able to clean a pizza oven chimney? The Interior code is clear. My concern is that the design that I am thinking of will properly draw and make the oven work well. Any thoughts that you have to make that possible would be appreciated.
Thanks
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  #8  
Old 11-01-2008, 05:32 AM
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Thumbs up Re: Offset Chimney

Hi terraVista,
I have put a diagram of an idea over your original .pdf diagram.
The chimney void could be made from 304 stainless steel, around 1mm thick, (easily welded) to flow the smoke and gasses in as a direct line as possible under the constraints of your build. I would make the flue at least 8” as a 6” would not handle the amount of smoke until it got hot to draw as you hope. It would be very easy to dynabolt onto bricks both over your oven doorway and also the back of your face arch.
The diagram speaks for itself and would be a breeze to make.
My 40" Pompeii void and 8" flue are centrally located and symmetrical and it draws a treat.
Food for thought!.

Neill
Attached Files
File Type: pdf Vent-Flue offset.pdf (128.7 KB, 348 views)
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Old 11-01-2008, 07:37 AM
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Default Re: Offset Chimney

I like that shape Neil. It has the advantage of appearing to be releatively easy to clean from the oven side as well.

Travis
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  #10  
Old 11-01-2008, 07:55 AM
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Default Re: Offset Chimney

Freestanding ovens are considered backyard barbeques, and are not covered by code. You still want the most direct flue path for your smoke to travel. Sometimes building code is the distillation of experience and common sense. I'd avoid a horizontal smoke path.

As to your flue cleaning question, pizza ovens burn at such hot temperatures, and with ample air input that they don't build up chimney deposits like smoldering all night wood stoves. Still, you should be able to clean it if need be.
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