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Post by cobblerdave on May 14, 2015 12:29:16 GMT
G'day If you want go by a set formulae a chimney should be at least 15 per cent of the area of the oven mouth. If the chimney is square say 8 inch by 8 inch only count and 8 inch circular area in the middle as the outer corners draw poorly and shouldn't be counted. It's a pretty complex subject if you want to make it so. Make the vent leading to the chimney as wide as possible and as big a chimney as possible and you shouldn't suffer from smoke stains Regards dave
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Post by darrellme on May 14, 2015 16:04:13 GMT
Oh, the other quick question is how long do I leave the former for the arch in place before trying to remove it.
Thanks
D
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Post by darrellme on May 23, 2015 10:45:48 GMT
HI All
Just a quick question, I'm at the point now where I'm going to layer the insulation blanket on top of the dome. Is it worth seeing whether I've got the space to put a later of vermicrete on top of the blanket. I haven't actually allowed for that so I might not be able to, but just thought I'd check to see what people thought. I have two boxes of insulation blanket, so I should have plenty anyway.
I'm actually planning on bricking up the outside of the dome with regular bricks as opposed to rendering it
Thanks
D
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Post by cobblerdave on May 23, 2015 23:25:55 GMT
G'day I rendered to the outside of blanket insulation. I found pearlite/ cement to be a real curse to work with, and it was an extra to the required insulation anyway. I used 2 incs ceramic than 3 ins of rockwool on that so I covered the insulation pretty well. Advantage of not using pearlite is a gain in drying time that stuff adds heaps of water that takes ages to remove. Due to kids climbing on the oven I got cracked render and decieded in the end to brick over the oven. Due to lack of space I 1/2 ed the bricks. Worked out really well the oven now has a tough water resistant shell Regards dave
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Post by darrellme on May 30, 2015 9:52:10 GMT
Thanks Dave, thats good to know that the pearlite isn't necessary. I'm also going to be halving the bricks on the outside so it sounds like its a similar thing to you, which is good.
In terms of the firing of the oven, I'm on about my fourth fire now, I"m just wondering how I keep increasing the temperature inside the dome (its not currently insulated yet). I'm on the fourth fire and the temp is still in the 100's so far, granted I haven't built a bonfire size fire in there yet, but I was wonder what tips/tricks people might have
Thanks
D
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Post by cobblerdave on May 30, 2015 10:38:20 GMT
G'day Ditch the term "cure" add the term "dry" Keep those fires low and slow and the same size. You'll find as the oven dries the temps from the same size fires will increase. This is because the fires aren't using all there energies to dry out the water trapped in the build. The water boils to steam at 100C. 1 ltre of water expands to 1500 ltre of steam. Drives steam turbines to produce electricity and easily cracks ovens. Take it low and slow. A tin full of holes on a couple of bricks full of lite charcoal beads will provide a low slow heat source without the flame impinging on the roof. Dry then do the flame thing. Remember pizza temps are 400C plus, twice the temps of a domestic oven. So on the way to drying the oven take the time to cook something. This thing is a wood fired oven not just a pizza cooker. Cook a bit of chicken wings anything really. Regards dave
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Post by darrellme on Jul 22, 2015 9:08:54 GMT
Thought I'd add a few more pictures I've fired it up a few times and a few hairline cracks appeared in the outer area, I've attached photos. I don't think they are anything to be too concerned about. I'm concentrating on the chimney landing area and then I'll inspect the inside to ensure that everything is sealed up as it should be A quick photo of the chimney platform Although inside the chimney doesn't look as pretty, I don't think I need to worry too much about it though, do I? I'll hopefully start building up some longer, hotter fires once we have some more decent weather, I can then start on the insulation and outer brick work
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Post by cobblerdave on Jul 22, 2015 10:15:27 GMT
G'day Looking good from here. You got to be happy with what you've done Regards Dave
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Post by darrellme on Jul 24, 2015 18:00:43 GMT
Thanks Dave, Yeah I'm pretty pleased with it so far, had good fun making it, just can't wait to cook something in it now :-), and obviously finish it off of course
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Post by darrellme on Jul 31, 2015 13:14:34 GMT
Well, that's done it, lol. I created a hotter fire and a few bigger cracks have now appeared, whats the best way of fixing.repairing any cracks that are there. Simply dig out the as much as possible and stuff some homebrew in ?
Thanks
D
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Post by cobblerdave on Aug 1, 2015 2:31:59 GMT
Thanks Dave, Yeah I'm pretty pleased with it so far, had good fun making it, just can't wait to cook something in it now :-), and obviously finish it off of course G'day Why waste that heat. You might not be a pizza temps those lofty 450C temps but well within cooking range. You can cook nan bread for sure on a lower temp hearth. In fact it cooks better at low temps that don't burn the sugars and fats in a nan bread. Anything you stew make sure you seal in in well a wood fired oven is dry heat. If you cook fire in the oven you'll find it a great experience. Try chicken wings they are not to thick and are hard to burn. If things are cooking to fast move them away from the flames and cover with cooking foil. I cook most things these days without getting the oven to pizza temps and waiting for it to cool. It just takes practice. So why not start now. Regards dave
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Post by darrellme on Aug 1, 2015 18:35:52 GMT
Oh, I didn't waste the heat, I tried to cook some bread in it, but I think the cracks meant that heat went pretty quickly, so I ended up with half baked bread.....although I may have gotten the mixture all wrong on the bread anyway haha, so perhaps that was it.
So, a couple of questions. Do I simply hack out the cracked mortar and replace it with some nice new stuff? If so do I then have to go through the whole drying out phase again from scratch? In terms of cooking stuff in it do you wait until the flames have completely died down and you're only left with the embers, or do you simply push the fire to the back/side and throw some stuff in to cook then ?
Thanks
D
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Post by oblertone on Aug 2, 2015 10:38:56 GMT
Regarding your cracks, are they letting smoke out when you fire the oven ? If yes then you'll need to dig them out in a V trench and refill with mortar, but this shouldn't take too long to dry out as it'll be exterior. If they're not letting out smoke then you could either leave them or just backfill for appearance and peace of mind.
As to cooking with/without embers, it all depends on what you want to cook. For pizza you need a high temp (450c +) and most folk manage this by pushing the embers to one side and occasionally feeding a stick of wood but only after the oven has become heat saturated*. For lower temp cooking such as bread, veg or meat you need to know what temp your oven is maintaining without a fire; so scrape out all the embers, block the entrance and let it stabilise before checking. Searing meat can be done at 250c + but only a short (Max 20 min) blast, bread needs about 230c and veg can also be roasted. Once it's down to 160c put your seared roast back in, seal it up and leave it until you are ready to eat. Spuds can go in with the meat but wrap in foil to prevent drying out. I did a marinated pork shoulder, gave it a sear at high temp then when the temp was down to 200c I put it back in and left it overnight (11hrs), not a scrap left after lunch !
All ovens are different and you need to determine the 'heat gradient' of yours (nb: This will change as the oven dries out), what you cook and when depends on where you are on the gradient.
* Heat saturation sound complex but isn't. On a full firing your oven will start off sooty inside, once this soot burns off you are at pizza temperature. If you keep feeding it fuel the oven will absorb heat over time until it becomes saturated, as above this time will reduce as your oven dries out with use so don't be put off if it takes 2hrs to get to 'soot free' when you first start.
Hope this isn't teaching you to suck eggs.
Paul
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Post by cobblerdave on Aug 2, 2015 22:04:20 GMT
G'day cooking bread old school in a wood fired was a practiced art. Getting the heat deep into the brickwork took time. Time that the baker used to proof his dough. They would take a bit of that dough and stretch it out flat. This told them that the glutin stands had formed that would hold in the expanding CO2 from the ferment that would provide the soft open structure of the loaf. They threw this into the oven hearth floor to proof the heat. It would brown and puff up in the heat. Then they threw it in the bin.... The hell they did this was the bakers breakfast. The first bread of the batch! A bit of salt, some oil, a sprinkle of cheese. Someone took the time to call it pizza and make some rules. It was something exotic because no one else was up with the baker at 2 am in the morning! But pizza is really the first bread the bakers breakfast. Same with the pizza oven now, it's the first cook as the temps to hot for anything else Regards dave
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Post by darrellme on Aug 3, 2015 12:33:29 GMT
Cheers for the info guys, and nope, its certainly not teaching me to suck eggs. Unfortunately the cracks were definitely letting out smoke haha. I've dug out what I could and re-filled with the fire cement that you can get from B&Q. Its quite nice stuff to work with actually and I patched up the inside and out, so I'm hoping to start up another fire in the next couple of days, although I may go back a stage and start a little smaller. The previous fire was burning for nearly 3 hours and soot still remained. Possible because of the crack and also possibly because of the wood, perhaps there is too much water content. I've brought a moisture meter to check the wood now, and I'll start drying some of my own wood out now too using the pizza oven. I also need to build myself a door too as I'm not gotten around to that part yet either, so many things to do, not enough time.
Great info on the heat saturation though, really helps, so thanks for that. Fingers cross I can get to that stage by the weekend (depending on the weather)
Cheers all
D
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