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Post by pesho77 on Apr 20, 2015 11:48:39 GMT
Is it a good idea to have a bafffler on the out let chimney of a Pompeii oven ?
Does this just mean that toxic gases cant escape the flue ?
Would more air at the inlet mean more heat like a bbq or are these hot enough ?
can the heat be conrtoled more easiy with an air blower (like a bbq dragon) ?
Pete
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Post by oblertone on Apr 21, 2015 0:17:47 GMT
A baffle in the chimney would only force the flue gases out of the front arch so would be fairly pointless. As to using a blower, you might get up to temp a bit quicker but at the cost of more fuel. As your average Pompeii will reach 500c normally aspirated I wonder what you could cook at 600 ?
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Post by pesho77 on Apr 21, 2015 8:46:13 GMT
OK so what about less fuel at a lower temp, could you still achive and maintain say 350c with a blower.
as these work with bbq's i cant see why they wouldnt work with a wfo.
Has any one used an istalled temp probe / can any one recomend one that can take the 500c for prolongued periods ?
Pesh
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Post by pesho77 on Apr 21, 2015 8:51:47 GMT
I should add here, i more interested in temp control not just a higher over all temp
Pesh
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Post by cobblerdave on Apr 21, 2015 21:45:00 GMT
G'day
A wood fired ovens is self regulating. The mouth of the oven is 63 per cent of the interior dome hieght. The mouth obout 1/2 the oven width. Once a fire established and the heat kicks back off the dome and makes the fire burn its best. It's pretty efficient the carbon burns off the dome and the smoke is held in the top third of the dome and completely burnt. Dry wood and dry oven and there is no visible smoke. The chimney is external to the oven and is there to take the smoke away from the user the entrance is there to stop the effects of wind
The hot gas exiting the oven mouth at the top the draws fresh air at the bottom. You don't comtroll the air intake or exhust only the amount of wood. Flames licking out the oven mouth is wasteful so you back off.
The WFO is a mass oven and the heat stored in 3 to 4 hours of burning in the mass of brick/ clay/ refractory will give you usable cooking heat for 2 to 3 days of cooking and you follow it slow drop of heat to what you cook. ( that's if it's properly insulated)
From my experience over the years with wood burning and charcoal burning BBQ is that you don't damp down the exhurst you comtroll the air intake to control heat. It you do damp down the exhurst you get an incomplete burn and much smoke. The best example that most wood know of this would be a webber kettle.
Regards dave
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Post by pesho77 on Apr 22, 2015 12:06:58 GMT
Thank you very much Dave.
While on the topic of WFO geom, can i ask what is the length of the oven opening as a % of oven diamater / height ?
Pesh
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Post by cobblerdave on Apr 22, 2015 22:54:02 GMT
G'day
I think it would be about 4 times the width. Just my gut feeling. I think it would be governed by the practicalities of operating a peel or fire pooker rather than a formulae
Regards dave
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Post by pesho77 on Apr 23, 2015 8:26:59 GMT
Thank you
Pesh
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Post by pesho77 on Apr 23, 2015 10:19:10 GMT
Can i ask you to confirm 4 times as lond as it is wide please
if the oven has a 1m dome it would have a door height of 63cm and a width of half a meter, but a length of 2 m.
do you mean 1 quater of the dome / half the door width ?
Pesh
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Post by chas on Apr 23, 2015 12:13:45 GMT
Can i ask you to confirm 4 times as lond as it is wide please if the oven has a 1m dome it would have a door height of 63cm and a width of half a meter, but a length of 2 m. do you mean 1 quater of the dome / half the door width ? Pesh A bit of confusion, Pesh... a '1m dome' - quite a usual size - is 1m in diameter. The 63% rule applies to the height of the dome which is, of course, the radius ie 63% of 500mm giving a door height of 315mm. In practise, that's a bit low for some of us, so we jack the dome up on one or two courses of bricks before we start, and take 63% of the combined radius and starter brickwork. You're right, a 2m diameter oven would have a door of 63cm, but not many of us have built ovens that big... Hope that helps, Chas |
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Post by cobblerdave on Apr 23, 2015 21:42:10 GMT
G'day
Woops read the question wrong
The doorway to a dome oven ends up being about roughly 1/2 the width because this is were the hieght of the door bisects the shape of the dome.
But the dome can be 1/2 sphere or a a flattened curve say with starting with a solider course. Ony way to accurately find a measurement from acurate drawings. Or like me draw the thing out full size on an old fridge box flattened out . A half section on the dome draw on this the entrance hieght and were its to meet the dome. This measurement can be then transferred to a top view giving you the door width.
Pretty important really as you need this to start the oven as of course you start at the bottom.
I cut me full size drawing out and used it for reference during my build. I'm a visual person and found this a great aid as you could lay at the top view on the top slab and it helps you position the oven on the slab. Even so my oven ended a bit far back in hind site
Regards Dave
ps you have to draw in brick thickness in as well as a 1/2 brick is 100 mm and that's a lot to be out
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Post by pesho77 on Apr 24, 2015 7:38:27 GMT
Thanks Chaz i had missed that should have been obvious realy
Good idea to modle it first Dave, my plan is to make the dome + door way out of polystyrene and build around it.
Pesh
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