pompeii oven construction began today

[janprimus]

Chad, The rigidizer sounds pretty cool! But I've read a few postings on other forums (mainly regarding kilns and foundries) that say the rigidizer makes the blanket brittle and can crack if bumped into. Although that shouldn't be a problem for the oven--provided the dome is enclosed...

You know, the people I found on Ebay with the Kaowool suggested That I could just coat my dome with a thin layer of mortar and stick the kaowool right to it. He also suggested that the rigidizer might not even be necessary as you are going to be covering it with a layer of mortar and then stucco later. I also asked if the mortar and or the rigidizer would compromise the insulating value of the kaowool and he said it does not, that it just makes a tough shell of the outside. The inside would remain soft and fluffy unless of course you were soaking he kaowool in a slurry of concrete. I do know from the construction business that they use a very thin coating of a stucco like material called dry-vit on the outside of a lot of commercial buildings as long as it is high enough to not have people putting their hands through the relatively thin and brittle coating.
Pax
Chad

[paulages]

no longer a theory!!!

okay, so finally i got some free time and it stopped raining for a few hours, and my vent/chimney finally came to life.

my camera batteries were dead, so i missed some interesting photos showing how i tied all of the bricks in the arch in the "tunnel" together, including the initial arch that supports my oven opening. to summarize, i just staggered the bricks here and there to tie everything together, and at the top, used a 2" section of brick to hold in the long pieces that frame the vent opening. well, enough explanations---as they say a photo is worth a thousand words (i hope)...

the line at the top is where the old archway ends




you can see here where i cut the middle four bricks into 2 1/2" and 6 1/2" sections, and used them to straddle the vent opening, holding the middle section of the arch together.

[paulages]

venting my frustration

this cost me $1 at my local recycled building supply (the metalbestos sections were $30 from there also). i cut the bottom to the curve of the arch, and bend the tabs out for "feet."



i set on the arch, and used the weight of the chimney pipe to hold it down solidly, and mortared it in place.

[paulages]

i really hope my vent opening is large enough! it's 8.5" x 4.5" inside the archway, tapering up to a larger cavity inside the galvanized vent piece. i guesstimated based on watching it draw and vent when i cook in it, and i think it'll be fine. the chimney will be pretty tall to help increase the convection and draw.

am i shortsighted for using that galvanized section instead of ceramic, when the steel will eventually corrode?

[Marcel]

Great Vent And Chimney Photos, Paul

#47

(M) Your super photos came just when I need them. Thanks!

(P) " (the metalbestos sections were $30 from there also)

(M) I guess that would be the shiny double walled piece that seems to be about 3' long-tall?. The word asbestos is alluded to and I have seen it before. Evidentally there must be no danger as such flues are still being sold at my Home Center.


(P) " i set on the arch, and used the weight of the chimney pipe to hold it down solidly, and mortared it in place."

(M) Smart, effective and neat! Also how you straddled-staggered the different size bricks. But what else would one expect from an Oregonian?

(P) "i really hope my vent opening is large enough! it's 8.5" x 4.5" inside the archway, tapering up to a larger cavity inside the galvanized vent piece."

(M) Paul, my concern is that one could make the flue too large and perhaps divert too much heat with the smoke. The opening you made looks just about right. Luis Arevalo's isn't much bigger and he says his oven draws fine. After all, we're not making a conduit for fluid. Gases will escape, .... particularly after eating pizza.

Ciao,

Marcel

[paulages]

we'll see...i don't want to fire it up too soon to see how it draws, but i also don't wat to wait until the roof is finished and discover i have to remodel. i'll give it a couple of days and then fire it up. actually (not sure whether this is good or not ) the top four or five bricks on the front of the arch were so tight i couldn't fit ANY mortar in. they are completely dry laid, with mortar packed on top. i figure the weight of the chimney will help hold it solid along with the wonderboard that will surround it to make the walls.

[paulages]

and yes, clarification: metalbestos is 3' doublewall insulated chimney sections (8" interior diameter).

[dmun]

Am i shortsighted for using that galvanized section instead of ceramic, when the steel will eventually corrode?

From the look of it, that thin wall galvanized item is for heat duct use rather than flue service. If it were me, I'd plan on it's corroding out, and coat it with a couple of inches of refractory cement, using the flue as a form, leaving you a good flue transition after the flue rots through.

In wood stove instalations, the single wall stove pipe rots out in maybe three heating seasons, and has to be replaced, and I think that's thicker gage than what you've used.

[Bob C]

Paul,


your oven looks great...I wish I had the patience that so many of you have...not that I'm unhappy with mine...I just decided to start using mine before it was completely finished. But again, great work and fantastic support you provide to others.

Bob

[Bob C]

I think it would be interesting to see what size flue is being used on all of these ovens we are building...I have two sections of an 8" x 12" flue and it works fine...I'm wondering if a smaller flue would work even better...
Let's here some responses.

Bob

[svtlightning]

Paul

The arch vent looks great.

I was concerned that the galvanized pieces would outgas when the oven was fully fired and exposed to high temp for extended periods. But now that I have a temp gun, the temps are not as high as I expected. I don't think it will be a problem.

Mike

[Marcel]

Insulating transitional heat duct, and vent size.

From the look of it, that thin wall galvanized item is for heat duct use rather than flue service. If it were me, I'd plan on it's corroding out, and coat it with a couple of inches of refractory cement, using the flue as a form, leaving you a good flue transition after the flue rots through.

In wood stove instalations, the single wall stove pipe rots out in maybe three heating seasons, and has to be replaced, and I think that's thicker gage than what you've used.

================================================== ===

#47

(M) Paul, I would guess you are planning on following through on Demon's suggestion but instead of refractory cement, how about a perlite based insulating concrete on top of chicken wire. I suspect that that lower area of the vent would wick a lot of heat away and insulating it might be an advantage? ___

================================================== =====

(M) On a related issue, there has been a lot of interest generated over the question of vent and flue size so I'd like to offer this question for everyone's consideration:

(M) If many early, and some late model ovens have *no* vent &/or chimney but simply let the smoke out the entrance, doesn't that suggest that the whole issue of vent-chimney size is not that critical? ___

Ciao,

Marcel

[paulages]

marcel,
i think it's only critical if you are concerned with having all of your smoke go up the chimney. contrary to bob's belief, i haven't been patient at all, and have been cooking in it with no vent for quite some time. it works great, but i need a roof.

i'm gonna consider the ideas here for that galvanized section today. i'd like that section to be structural as well as just a vent--that is, i'd like it to be able to hold up the chimney. i was planning on wrapping it in chickenwire and coating it with a couple of inches of the insulcast, but this would only achieve the latter and not the former. i'm gonna check out ceramic sections today. i sure as hell don't want to ever have to take anything apart on this and repair it!

[Bob C]

Paul,
I'm glad to hear that you've been using it right along. I like the arched vent also. Very good work! Personally, I'm having trouble deciding on my finish. I like the look of the "igloo" but I think a complete enclosure would be a better served as a shield against New England winters. AAAAGGGGGHHHH!

Bob

[paulages]

thanks bob. yeah, patience is not my greatest virtue... i really like the look of the fully enclosed ovens. it really looks authentic. but there are some great looking examples of igloo-style ovens out there (robert musa for example).

i found this pile sitting out in the rain and decided to put it to use.


i do like the idea of complete masonry construction. as someone mentioned in another thread, if it's worked so well for the greeks, italians, lebanese, etc...for so long, it oughta last in my backyard.

so gimme a little while, and i'll be back with my revised vent/chimney pictures.