Just about to build a pompeii oven :D

[Roastie]

Hi l'm Shelley from Kent UK, and have been interested in building an oven for some time now, l have found lots of information and advice from reading this site - l am so pleased it's here.
So firstly thank you to those of you who had the initiative to start such a forum.
From an oven fancier's pov - it's invaluable.

l have on order (which were very difficalt to find in the UK) 500+ low duty firebrix - l am hoping this will be too many rather than not enough, the company l have purchased them from couldn't make an order any smaller then 556 -(l believe the number was)?
l also have on order a flue and a cowell for the top.
l have a pretty good idea how to put it together, the only thing my head is having difficalty disciphering is how will l put the oven floor together, l saw the poto bucket pics, thank you sir.
l noticed how you made a wooden framework with which to pour the cement into - but how are you supporting this?
l have at my disposal several sheets of galvanised parrot mesh/net with which to lay into the wooden framework but is there anything that should go beneath this like a granite slab or other o would it not be heat proof?
Any help would we greatly apprediated.
Thank you so much in advance.
Shelley.

[dmun]

Good luck with your project. You have more than enough bricks, but as hard as they are to get in the UK, you should have no problem selling extras on eBay.

As far as the concrete floor, it is supported on the edge by the block stand, and the center is either overlaid with concrete board (I don't know UK brand names) or inset with cheap plywood or chip board, supported by a wooden structure from below. No need to be too fancy here - no one will ever see it. I used old skids cut to fit, and held up with scrap lumber, but most people do something fancier than that. You fill the holes in the blocks that you haven't filled with concrete bags, or any random junk.

Most people support their forms in the middle where they can bulge out, either bracing them from the ground on the diagonal, or using twisted wire through holes from side to side. I'm not sure how important this is - I didn't notice much sideways thrust.

This support slab should be reinforced, usually with re-bar, but the grid that they use in sidewalks should do fine as well. Parrot mesh is a term unfamiliar to me.

Sounds like you're doing great. Don't forget to insulate between your support slab and oven floor.

[Roastie]

Thank you for that,
l have some help now with the construction of the chimney and flue, l wasn't sure about this, but a kind gentleman from Nationwideflue who should be here searching for my posts has an ebay shop where he sells flue's, cowellings and alsorts re: fires and the like. - l am hoping he will point me in the right direction, as to the materials l need to construct the chimney.
Does the oven floor hafto have the blocks you spoke of beneath? l can understand insulating them and l think sand would probably be the best bet there. However l was going to just brick up a cabinate of sorts and from there lay the oven floor ontop?
Does this sound okay?
Shelley.
PS - Parrot mesh for any of you that are confused is just a strong steel/galvanised grid which you would find on a large parrot cage.

[Nationwide Chimneys]

Hi Roastie, following our previous discussions with regards to the flue system for your Pompeii Oven I have searched this site and have found a similar installation within the Photo Gallery. What is concerning me is the diameter (size) of the flue system required as this needs to be calculated in order to allow the correct volume of smoke to pass through it at one given time. If the flue system is undersize you will prevent the smoke from escaping and if the flue is oversized you will loose alot of heat up through the flue system. The Pompeii oven is very similar to an open fire which is normally a minimum flue size of 200mm (8") diameter, however that is based on an opening of 550mm (22") wide x 500mm (20") high. I would personally recommend you to use a 125mm (5") diameter or 150mm (6") flue system which is a common diameter for the likes of solid fuel and wood burning stoves.


many thanks

[dmun]

Brick ovens are very heavy. Placing them on a cabinet, or even a massive timber structure, will introduce unwelcome flex into the system, and might cause cracking. A solid slab, and a concrete block structure is the usual method, although as an alternate a similarly strong and rigid frame welded up from structural steel can be used. Remember, we are talking about a lot of weight here.

Sand was a traditional underlayment for the oven floor, but doesn't have much insulating value. Concrete made from vermiculite or perlite and portland cement is much better, and a modern refractory insulating board is better still. One thing that experience has taught is that there is never too much insulation. Under insulated ovens waste wood and time.

Flue size is traditionally calculated by the opening of the firebox in masonry chimneys. Although our opening is much smaller than a domestic fireplace, ovens do need to pull air and smoke around a circuituous route. An under-flued oven will tend to pour smoke out the front opening when the fire is started. Most US builders use an 8" round stainless flue system, or an 8" square refractory flue tile. This is the smallest size commonly available here.

[Roastie]

Thank you to Nationwide Chimneys and to DMun.
l have taken all considerations on board and am quite satisfied reading through this forum and with what you both say, Nationwide Chimney's is correct in what he's saying that too big a flue would surely lose more heat, and what l would imagine the important thing is, IS the pull and draw of the oven and the vent for the smoke, a fire would draw better on a smaller opening - surely? So l'm going for the 6''
As for the structure / cabinate of my oven, it will be a 9'' 'double brick wall' with ties between, filled with sand and the concrete block beneath the oven floor (of fire brick) will be supported by angle-iron and the strong steel mesh l spoke of in my previous post.
Does this sound satisfactory?
Thank you for your help, we are indeed getting somewhere.
l cant wait to get to work on the oven and this weekend will see the start.

[dmun]

Originally Posted by Roastie

a fire would draw better on a smaller opening - surely? So l'm going for the 6''

I just double checked the pompeii on-line plans: here's the chimney specification:

The following table outlines the internal diameter of the chimney for the different oven sizes:
Oven Size Chimney Diameter
32" - 36" --- 8"
40"+ ----- 10"

You could of course use a smaller chimney, but at the cost of some smoke in the face. Less of a problem outdoors, more indoors.

As for the structure / cabinate of my oven, it will be a 9'' 'double brick wall' with ties between, filled with sand and the concrete block beneath the oven floor (of fire brick) will be supported by angle-iron and the strong steel mesh l spoke of in my previous post.
Does this sound satisfactory?

That sounds great. As strong as needed. "cabinet" means a flimsy chipboard box under a kitchen counter here in the States. Two countries divided by a common tongue.

[Roastie]

ha ha -
Yeah we have them too, called the same. l can see why you worried now.
l did mean a cabinet 'of sorts' - didn't quite know how else to describe it, apart from saying a bricked box of sorts?

Thank you for your specifications's most helpful.
l will bear that in mind. l am hoping to build quite a large oven of around 40-42'' maybe?
With a large (ish) opening 12-14'' wide by the same (ish) high.
ls there some kind of metal netting you would use beneath the flue at all?
l am worried that l might lose some heat, l guess only you guys with experience - would know?
l'm taking it all in.
Please forgive me if l sounded a tad rude earlier - l never intended it that way.
Shelley.

[nissanneill]

Hi Roastie,
I have been sitting on the side reading your post and agree with some of the information received. I have just finished a 40" Pompeii with a 10' high 8" flue and it works an absolute treat.
the last thing you need is to spoil the front brickwork with smoke when you start firing (and it is only for a few minutes) but mine is great, no smoke what so ever out of the front.
The complete build is on this forum but spread around a bit. Check it out at:

http://www.fornobravo.com/forum/f8/n...-1-a-2005.html

then

http://www.fornobravo.com/forum/f21/...-4-a-2045.html (Neill’s Pompeii #4)

then

http://www.fornobravo.com/forum/f21/...10-a-2119.html

with the final, the spark arrester at

http://www.fornobravo.com/forum/f21/...ster-2333.html

Don't hesitate to contact me if you need more specific information and good building.

Neill

[Roastie]

Thank you for that Neill
l appreciate all anyone hasto say, l do listen to it all and have gleaned a lot from all of you. lt's a great forum this.
lt's nice to hear all of your points of view, bcause l really was afraid of losing a lot of heat thru an 8'' flue, but l will trust everything you all say and go for it. Everything is slowly coming together for it now. So thank you, all of you.
Has anyone used a damper on the flue and how well does that work?