Chimney Primer Design Styles, Chimneys and Finish Discuss Chimney Primer in the Pizza Oven Design and Installation forums; Bruce. I played around with your calculator. If you intend on a tapered chimney, like those pictured above, what dimensions ...

[mfiore]

Bruce. I played around with your calculator. If you intend on a tapered chimney, like those pictured above, what dimensions do you enter? Top dimension or bottom?

[brokencookie]

Mike
I'm not sure. The dynamics of a tapered chimney are a lot different. Maybe one of the engineers on the forum can lend us a formula. If not, I would use the smallest measurement. That way you could be sure of the draw since a larger diameter would only draw better.
I'm of the over kill school of building. If it is worth building, it obviously needs crossbracing, large support beams, heavy brackets, deep footings etc. I just finished a septic system up grade that should work for 25 fiber eatin people for the next 100 years.

[mfiore]

I'd luck to return to this discussion. Several questions.

First, regarding the above discussion on round vs. square, it appears that the square flue tiles are measured by the outside measurements, while the round are from internal dimensions. No logic, but I'm sure there is a reason. As it turns out, according to Superior Clay website Superior Clay Flue Liners
an 8.5x8.5 square flue tile has an effective area of 49 sq inch, while the 8inch round has an area of 50 sq inch. Essentially the same.

How important is the taper as you go up.

I plan to build a tapered vent entry into my arches. Mines not done, but similar to this


The bottom dimensions will be about 4.5x 21.5 inches, tapering up to a dimension of 4.5x 12.5 inches.

Locally, I can find 8x13 inch flue tiles that will span the opening. This would be in increase in the effective area as vent opening transitions into the flue tile. Will this cause a problem?

Is it important to alter the flue tile for the chimney to continue to taper as it goes up, like dmun and Les did -



Even more importantly, can my arch support this weight?

Thanks in advance. This chimney stuff is giving me a headache.

[Lapenna]

[QUOTE=mfiore;43473


Even more importantly, can my arch support this weight?

Thanks in advance. This chimney stuff is giving me a headache.[/QUOTE]

I too, would like to use clay flue tiles on my oven, up to about 3' with the stainless insulated chimney inside of the tile extending 4' above that, both of which go through the top of a redwood pergola, but I don't know if the exhaust manifold/oven arch can support the weight. Any comments? Thanks

marco

[dmun]

would like to use clay flue tiles on my oven, up to about 3' with the stainless insulated chimney inside of the tile extending 4' above

I'm confused. Why would you use a stainless liner inside a clay liner? What goes on the outside?

[Lapenna]

Originally Posted by dmun

I'm confused. Why would you use a stainless liner inside a clay liner? What goes on the outside?

After thinking about it more, I guess that i only need the pipe on the top of the clay liner terminating with the spark arrestor.

Can the oven handle the weight of the liner, or will I have to fabricate some kind of additional support? Thanks

[Ken524]

Hi Marco,

Welcome to the forum! I notice you're in Cinci. I'm right down the street in Louisville .

If you go with a product like Duravent (what I used) you only need 2" of clearance to combustibles. You should be able to put that right up through your pergola with no problem (or maybe rework the pergola slightly to give the pipe 2" clearance). No need for the chimney tile.

The DuraVent system is not cheap, but it does a heck of a job. When my fire is roaring, my pipe is slightly warm to the touch. I can keep my hand on it indefinitely so it's not going to burn anything.

You can mount the DuraVent directly to your oven vent. No clay liner necessary.
DuraVent UL103HT Chimney System

If your oven will have a roof, you can add bracing in the roof to help stabilize/support the pipe.

[dmun]

Can the oven handle the weight of the liner, or will I have to fabricate some kind of additional support? Thanks

Yes, your oven opening will support any reasonable length of clay flue liner, and of course the lighter stainless systems. I have a two story chimney, with maybe 10 lengths of 8" square clay flue tile resting on my dome/entry without problems. The external masonry chimney is supported separately.

[anduzy]

Not to change the subject or anything...But why do you feel the need for a chimney at all? I've been using my Pompeii oven 3 years & my Premio 120 for 2 months and I'm not liking the whole chimney idea.

[mfiore]

Please clarify. Do you not have a chimney or vent system on your Premio? I guess I don't see why you wouldn't want a chimney. I have little experience with the alternative, but it seems hot smoke pouring out the front of the oven is undesirable.