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enzo 11-29-2009 01:28 PM

What is a scary fire?
 
1 Attachment(s)
I have tried to burn my oven to get the dome white, but I haven't got close yet. Should the flames be reaching into every corner of the oven? including the top of the dome? And if so, do I continue that rate of flames until I see the dome change colour? The height is my main concern, its about 22 inches above the floor. Does this sound too high?

Photo attached.

nissanneill 11-29-2009 01:57 PM

Re: What is a scary fire?
 
Hi enzo and welcome,
I just picked you up as a fairly newbie and like to keep a list of the participating Aussies on board.
It looks to me like you have built a vault type oven. The wall thickness will govern how much heat it will absorb and hold - thermal mass, (together with the material/brick type, thickness), type of wood, dryness, density, fire intensity and time alight.
From your picture, you have what I would normally would call a 'scary fire' as it is coming out of the front arch. My fires are a little intense and my dome starts to change colour after about an hour. I use hardwood, usually dries river red gum and also some eucalypt cut down less than a years ago, so the fuel shouldn't be much of an issue.
I can't see how a 22" oven height is a problem as the heat generated within your oven will rise and it is close to all of the Pompeii's built.
How long do you keep this ferocity fire going? It needs to last around 1 to 2 hours to change the dome colour.
Do you have a laser infa red thermometer to measure the oven temperatures, wall, top and hearth?
How thick is your oven wall?
How have you dried out the moisture from within your build? My oven got rather wet back a while ago and it took considerably longer to drive out that moisture and the dome only turned white at the very top of the dome, no matter how fierce I got my fire. Hell, I also use a leaf blower sometimes to really get it going if it is reluctant to burn properly and you can almost melt steel in the oven. have bought some rather dry expensive red gum ($300 / ton) which didn't want to burn very well in the oven but when I put in some greener gum, it took off and performed as expected.
What sort of timber are you burning? Softwood will burn almost as hot but not for as long as good hardwoods. Larger/thicker split timber (around 3-4" in diameter and a couple of foot long) is better once your fire is well established rather than smaller lighter timbers.
You are not far away from it so keep up with the fires, ensure tht your oven is dry and good luck.

Neill.

PS. Where abouts in Australia are you located?

Les 11-29-2009 02:00 PM

Re: What is a scary fire?
 
Enzo - the height of mine is a little less than 21 for a 42 inch oven. I have my flames licking the top of the dome for a couple of hours before it starts to burn off. The flames in your pic look like it should do the trick - they are coming out the front. If thats not enough fire I don't know what is. :confused:

Les...

texassourdough 11-29-2009 02:00 PM

Re: What is a scary fire?
 
It is not that it turns white but rather that the black soot and tars that turn it black burn off. Once your oven is reasonably dry that should happen in about 45 minutes to an hour with a good fire. The flames don't have to fill the oven to get there but it does speed things up.

Good Luck!
Jay

enzo 11-29-2009 02:41 PM

Re: What is a scary fire?
 
2 Attachment(s)
Thanks for the replies.

Yes I'm a newbie, the oven is a barrel vault and was built around a wooden template which is being burned out, in the pic I posted. I haven't burned it that ferociously since, all of my fires have been kept well inside the oven and by the sounds of things nowhere near scary enough! As far as other details go the oven was supplied in kit form from a commercial supplier, the photos show some of the construction. There are a number of insulation barriers on top of the bricks including 20-30mm of ShiraLite, then Thermal wool blankets and about 50mm of normal mortar render.

I'll keep persisting with nastier, longer fires. I have read somewhere on the site that barrel vaults are a poor choice for cooking pizza's, perhaps I've made a bad choice in ovens.

BTW Neill, I'm from Melbourne.

Thanks for your reply, it's very appreciated and helpful.

dmun 11-29-2009 03:39 PM

Re: What is a scary fire?
 
It looks offhand like your oven has no insulation over the dome yet. Adding the insulation will help a lot in getting your oven above carbon burning temperatures. We have seen barrel vault pizza, by canuk jim and others, it can be done. It takes lots of wood and lots of insulation over and under.

nissanneill 11-29-2009 04:58 PM

Re: What is a scary fire?
 
enzo
Thanks for your location, I've just updated my list of participating Aussies on this forum and you add to the growing Melbournites!.

Neill

Mitchamus 11-29-2009 06:45 PM

Re: What is a scary fire?
 
Barrel vaults make great pizza. :)

paulyboy 11-29-2009 10:12 PM

Re: What is a scary fire?
 
Enzo,
Mine is a concrete dome, but I lit my first full on fire on Sunday. It was wet and cold and it took a bit for the fire to get enthusiastic but once it was up and roaring it seemed like no time and my dome was turning white. Mine is really well insulated so I guess that helps, but it also has less mass than yours so should take a shorter time.
Good luck, stick with it, you'll get the hang of it.
Paul

ps. Melbourne WFO builders/owners rock!

enzo 11-30-2009 01:08 PM

Re: What is a scary fire?
 
Quote:

Originally Posted by Mitchamus (Post 73143)
Barrel vaults make great pizza. :)

Hi Mitchamus, I'd like to hear more from you about this!


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