pompeii oven construction began today

[Alan]

First link from Google, though maybe not the same manufacturer because they don't list 70 lb bags:

http://www.ablerefractory.com/datash...%2025%20LW.PDF

THERMAL CONDUCTIVITY
BTU/SQ.FT./HR./IN./oF

Mean Temp. "K"
400 F 1.91
800 F 2.10
1200 F 2.46
1600 F 2.97
2000 F ` 3.31

[paulages]

i coudn't find any product specs on the supplier's website, but the product you found is probably very similar. the 25 in the name denotes the temperature rating (2500 deg.).
most refractory products are named this way, but with some the number refers to the alumina content.

i would wager that any manufactured refractory product will outperform any anything you make yourself, but i believe much of the original point of the pompeii plans was to provide plans for an oven for which supplies can can be easily found.

perhaps there could be an 'advanced building section' in the forum for posts like jim's arch specs, discussions about more professional products, and other techiques that go a bit beyond the 'possible for anyone' point.

[james]

Paul,

I like the Advanced Pizza Oven concepts idea -- brick ovens for the hardcore builder. Let me think about how to do that. One idea would be to include all the real technical information there on arch design, insulation efficiency, concrete compression, etc. Issues that fall outside the range of the standard installation techniques. It could apply to both Forno Bravo refractory ovens and Pompeii ovens.

Do you think there is enough content for its own Forum section?

James

[paulages]

Do you think there is enough content for its own Forum section?

i don't know...maybe that's a question for everyone, or maybe for jim. perhaps there haven't been too many applicable posts yet, but i'm just thinking that in the future it might help someone wade through the different ideas and discussions if they are just shooting for jim's original plans.

[james]

I definitely think there should be a single set of core plans on www.fornobravo.com, that reflect the basic state-of-the-art. I can update the plan set on the net to reflect the internal foam forms, which I think is the best method.

Right?

James

[paulages]

since the foamboard method is the only one i've tried, i can't say whether it's best or not, but it sure worked well.
maybe it would take you, jim, robert, or someone else who has tried other methods, to try it and compare.

[paulages]

insulation time...

here's a photo showing about how thick i spread the insulation, and another showing it fully covered. i ended up going a bit thicker on top, as it seems to heat up considerably more there, and i'll most likely fill the sides with vermiculite once the exterior walls go up anyway.





i'll post before and after specs after it dries and i've cured the insulation properly.

[paulages]

it's alive!!!

okay, i'm having fun making pizza every night, but i guess i should move forward and get to work on the vent, walls, roof, and all of that other stuff i have to do before the rain comes. here's a nice photo of my oven in action:

[paulages]

the insulation seems to work fairly well, though i ended up going thinner with it than i'd liked, because i didn't wrap the oven in chickenwire first. consequently, i couldn't pack it on as thickly as i'd liked on the sides without it sliding off. the top has about 2-3 inches or more, but the sides are probably more like 1 1/2" -2" max. when the oven has been heated for a while (2 hours or more) the walls heat up to about 150deg. F, when the interior walls are 700-900deg. F. this is about a 100deg. drop from before insulating, but still higher than i'd like. what do the vermiculite insulated walls heat up to, anyone? since this stuff was free, i'll probably add another couple inches before all is said and done.

also, i am having problems reaching the temperatures i want. mostly in the floor, but even in the walls, i have to have a pretty damn big fire going to keep proper temperatures. having a 42" oven is probably part of it, but i also feel like i'm losing a lot of heat into the hearth. i definitely am burning more wood than described by some people on here.

[pam]

chimney

i am anxious to see how you tackle the chimney ...

i found a place in dallas where i can order terra cotta chimney sections for about $13 each ... they're 8" a-oval and about 2' long.

[Alan]

Paul, should you decide to leave a thermocouple on the outside or shove one in between the rigid insulation and the vermiculite before closing up the roof, remember that with the vermiculite added the outside of the chamber should be hotter than it is now. There should be less total heat loss, but a higher temperature on the outside of the chamber. Think of it as a bunch of resistors in series: dome walls - rigid insulation - vermiculite - outer walls - air interface, with the oven temp and air temps as "voltages" at the two ends. Adding more resistance bewteen a given spot and the outside will always bring that spot's temperature closer to the oven chamber temperature. Real heat transfer's not quite the same since the transfer to the outside air is horribly complicated, but the analogy still works in terms of when to expect things to be hotter or colder.

[james]

Paul,

My guess is that you are still driving moisture out of the bricks, mortar and hearth concrete. Give it a little time, and it will get better (hotter and faster) with each subsequent firing.

James

[paulages]

i can definitely believe there is still moisture in the hearth. it hasn't been ridiculously hot here in the NW, and the slab inside my barn (from posting #1, when i poured the foundation) is STILL not cured enough to move in with the acid etch staining coming next. granted, the hearth was poured outside, but it was also poured much later.

i hope you're right, james. right now i feel like i'm gonna go through my winter's firewood supply in no time...

[Marcel]

A letter to AbleRefractory insulation in Texas

To: AbleRefractory.com

I am in the process of building a masonry wood burning outdoor oven. The design is essentially like that of an igloo. The dome structure is made of refractory fire brick covered with refractory mortar.

The next very important stage is to prevent the heat from the inside of the "igloo" from escaping through the bricks and mortar.

I see that your Co. produces a very wide range of products to meet the needs of vastly different applications.My question to you is given the novice description of the 42" diameter oven, what product(s) would you advise as best suited to keep the heat inside the oven?

_____________, ____________,

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

I live in west central Oregon, not too far from Eugene. What are the closest retail outlets in that area, if any? ______

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

Thanks for your time and trouble,

Marcel Demiranda
marceld@efn.org

P.S. I am posting this inquiry on the Forno Bravo oven forum.

[jengineer]

oh Boy

Are you looking to set up a group buy? From the looks of their web pages I would think that these folks are more apt to deal in large bulk quantities. Say your local electic power producer that uses coal/gas to fire the furnaces. In the same breath they also point to insulating dentist furnaces.

From the pdf product sheets their mortors would be overkill for the oven however their blankets could reduce the size of the insulating. A possible substitute for the Vermin-Cellulite or Pearl-Lite?

You might want to follow this up with one of their sales reps.


je - lurking in so-cal