Marcel's Pompeii Oven photos Part 4

[Marcel]

Symetry isn't everything, ... is it?

#50

(M) "but let's hold the applause until the final act.

(M) Partly Duplicated from:

http://www.fornobravo.com/forum/newr...quote=1&p=1478

Forno Bravo Forum > Pizza Oven Installation Forum > Pompeii Oven Construction > Chimney Bricks: Thermal or Insulating? >Firebrick or insulated clay liners, again, ....

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(M) I will post another image on Forno Bravo's Photo Forum (here) that shows what happens when vanes are badly cut. I really will need to fudge a lot of mortar to accomodate the uneven height of rings of brick. I think my cutting error was exacerbated by crossing over the opening throat too late. I had already gone higher than the flat iron. But, if I gable this "turkey" no one but you who read this will know of my error. <insert> and, to be helpful to "Newbies" I need to show my goofs as well as my successes:

[Marcel]

2 more pieces of steel to support the chimney

#49

[QUOTE=Marcel]# 45
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(M) Mike, would flat iron instead of angle iron also work?

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(M) I have been considering 2 more pieces of about 24" - 29" flat iron to either support clay liners, or a chimney I'd build out of bricks.

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(M) So I don't know where, chronologically speaking, this post will appear but for the record, I bought 2 more pieces of flat iron. These are wider than the one I used to support the dome entry. I plan to use only brick for my chimney and am trying various layouts to avoid cutting. I have a plan which will give me a vent opening of about 18" x 2.75" for a total of 50 sq/in. The opening James recommends would yield about 78 sq/in but both Luis, and Paul have gotten by with less.

(M) Below? Next? should appear an image that shows the approximate placement of the 2 pieces of steel. The chimney will lay on both pieces:



Ciao,

Marcel

[arevalo53anos]

Hi, friends:

Following, some pictures showing vent type and building steps, along with the finished vent/chimney junction.
The last picture try to show the fire exhaust.
I hope this helps.
Luis

[james]

Paul,

Agreed. The taller you go, the better it pulls. Our oven producer even has a chart for oven installation inside the house, where they show how you can go narrower when you get to really long runs. It turns out that a lot of Italian ovens are installed in a rennovated farmhouse basement (Rustica), which was where they used to keep the animals (400 years ago). It's a great playroom for parties. They also put in fireplaces, game tables, etc.

Still, you need to get the chimney through the rest of the house, so there are some pretty long runs.

Great oven. You should be proud -- it looks great.

James

[paulages]

i just completed my vent moments ago, and i hope i don't have robert's problems!!...

it seems that, as with woodstove chimneys, having a tall chimney would be important, as it increases the flow. my chikney is 8' tall, and the vent is about 12" tall.

i'll go post pictures in my other thread...

[james]

David and Les,

Too funny. I just posted a photo of the Casa vent in a different thread, saying it would probably work well. It is made of the same composite refractory as the ovens, so it will get hot and draw well, and last a long time.

It would make sense to use a 12" round opening, which you can use with either a terra cotta flue liner, or a Class A (double wall) 10" system. You attach the chimney using an anchor plate. You could even use a 10" vent, with an 8" chimney.

The cost would be $120, plus shipping.

Les, I don't think round or oval matters -- just volume. Don't go too small where the hot air overwhelms your chimney, but otherwise it's pretty flexible. The vent itself tends to get hot and create the draw.

Drop me an email if this sounds interesting, and if there is interest, I will put it on the web site.

James

[Les]

Along these lines - the directions say that for a 40+ oven we should have a chimney diameter of 10 inches. This infers that it be round. Does anyone know if round is better than rectangular and what specific size would be optimum?

Les...

[dmun]

casa vent?

James:

Will you sell the casa vent piece to pompeii builders?



Could we get price/size/availability info?

David

[dmun]

flue funnel

I think some kind of funnel shape to the bottom of the flue would prevent smoke leakage out the front. I seem to recall that:

My vent arch is my problem child. the throat is too small (due to an error i made when pouring some repair mortar in that area). ultimately, i'm going to have to take the old arch out (or scoop it out from underneath) in order to accomodate a larger pipe and to enhance the draw. (but i'm dreading it.) it really works just fine, as is, if the wind isn't blowing briskly in the wrong direction.

a flue without a funnel can be a smoke problem, as this quote shows.

I was planning to build my funnel with split firebricks, but seeing the two rectangular flue sections side by side above has given me a good idea. The two sections could be sawn on an angle to create a refractory funnel, that would be strong and light, and would perfectly match the flue tile above it.

You can buy a refractory smoke chamber of the sort used in fireplaces, but they tend to be very expensive, as well as too big top and bottom.

David

[aikitarik]

Tarik
You might laugh, but those columns a wedding cake separators. I got them at a yard sale. They are plastic, but have not been damaged by the heat thru 3 full burns. I will be making some larger ones to finish my dome facade.
I'm trying for a peripteros temple look.

Mike

Ok, that DID make me laugh, but not in a bad way. That's awesome.

I've been planning on buying some sonotubes and pouring our columns out of concrete, perhaps mixed with perlite to lighten them up a bit and then stuccoing them and adding the capitals and such.

I need to do at LEAST 3 to frame the wood storage, and we may still frame the doorway with a pair as well. When I get to the BBQ, we may need more, but probably not.

[svtlightning]

Tarik
You might laugh, but those columns a wedding cake separators. I got them at a yard sale. They are plastic, but have not been damaged by the heat thru 3 full burns. I will be making some larger ones to finish my dome facade.
I'm trying for a peripteros temple look.

Mike

[Marcel]

How important is the area devoted to the chimney?

Marcel

I used two 24" long angle. Layed across the vent landing area. Spaced ~ 9" apart. The flue sections are set on top of this. I used angle for the vertical support as well as horizontal. Maybe some pictures with show what I am unable to describe.

Mike

#46

(M) Thanks, Mike. Your explanations were clear although I didn't actually see the vertical supports. Now, a few questions for anyone:

1- Mike used 2 large clay flue sections. I am concerned that such a large area may give up the dome heat too quickly. Does anyone know the relationship between the size of the vent opening and the effiiciency of the oven? ___ I'm sure there is a point of diminishing returns at both the large and small end of the scale but is anyone aware of a "scientific" or statistical study, such as the one that dictates about 60% of the dome height for the door height? _____

2- I am gravitating away from clay liners since they force a specific size and shape of the flue. Instead, I am thinking of using brick, perhaps the red kind with holes in which I could insert re-bar. Comments? ____

3- If I use brick, I wonder if an insulting brick would help prevent a wicking away of the dome heat? ____

4- If I can't find insulating bricks, would red clay bricks (*not* concrete) be better, or should I use my existing over-buy of the same thermal bricks as used on the hearth floor. Perhaps Jim Hatch could address this? ___

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(M) I layed a couple of courses yesterday and probably have about 4 -5 more to do. I had to stop because my mason's sand had gotten wet. I find it much easier to mix refractory mortar ingredients dry before adding water.

Ciao,

Marcel

[aikitarik]

James, how much is that vent piece? I've got a great vent hole in an archway, just haven't quite worked out the vent transition to the clay chimney pipe.

Also, Mike, where did you find your columns? That's exactly what we have in mind for our oven, including 3 columns in front of the cement blocks under the oven.

Regards,

[james]

What about this. It is one of the two vent pieces that comes with the Casa ovens. You could readily use it for a Pompeii vent.

[svtlightning]

and another