[maver]

Originally Posted by klaatu

The pre cast one takes 75min to 90min to burn clear with an additional 30min burn to soak in the heat. After the pizzas, the fire is cleared out and some food goes in ( a chicken, some potatoes ,some garlic, a cobbler) . 120min later and the little bi metal temp guage says 250F. If you burn for 4hrs it will be the same. My guess is that it is thin walled and or badly insulated.

I agree, this sounds like it is poorly insulated.

Originally Posted by klaatu

The brick one needs 4or5 hours get right but man o man it sure stays right. He can cycle stuff in and out for 8 hours and in the morning it usually is 250F or more. I'm guessing a firebrick , 8" of cladding and well insulated..

I think you are also right here, the cladding is likely very thick, but it may also have inadequate insulation. Other variables include how well seasoned the wood used is and how 'aggressive' the fire is. Robert Musa has been quoted here as saying something to the effect of 'you want a fire that makes the kids say "yeah, dad, add more wood" and your wife say "if you add another piece of wood I'm calling the fire department".' Do you know what temperature either of your friend's oven reaches? I will make pizza in an oven anywhere from 700 (a bit too cool, usually only if in a hurry or I get distracted in my oven temperature management) to 850 (I've used 900 hard to avoid some portion of your pizza burnt beyond good eating).

Originally Posted by klaatu

Would a home built oven with a 42" dia. X 21" dome and a 13 1/4"tall X16"wide inner door with one firebrick, 1"of cladding and perlite bring me this? Would 2" of cladding , how about 3"? The hearth is one brick in a herringbone pattern run out to the outer door. 3" of perlcrete under it and perlite over it..

With a dome made of 1/2 firebricks (4.5") 1" of cladding should be more than sufficient if you have good insulation. 3" perlcrete under should be adequate, and you want 6" at least over the dome (or better yet, a ceramic fiber insulating blanket and less perlite). I am interested in some of the recent forum posts here regarding a thinner dome with no cladding (3"). I suspect that would heat up faster, I'm just not sure how long heat would be retained. If your primary purpose is pizza then this may be superior. Since you are interested in varied uses, I'd use 1" cladding (I have just a little less than that) with 4.5" bricks.

Originally Posted by klaatu

I've seen guys write in on differant sites saying that thier dome turned white after a 45min burn , did 12 16" pizzas, 8 2lb loaves of bread,2 pies, 2 chickens, a goose ,a 4"X12"X12" lasgna 6heads of garlic, the partridge and dried out the pear tree for the next burn. The next morning
still at 350F..

You'll find similar posts here. Realistically, if I have my oven in fairly frequent use (so that the bricks haven't taken on moisture) I have a 60" burn time (with white dome) before pizza is ready to go. If I were to do 12 pizzas, by the time the oven has been kept hot for that long (another hour or so - less when I start using my outdoor prep area) then it takes an hour to drop the oven to baguette temperature (around 600). After that I can roast meat or cook some beans. If I do use the oven to dry wood for the next use the oven will probably be cool the next morning (I have not checked temps with this). If I just put the door on with a pot of beans in the oven, it's still usually 320-330 the next morning.

Originally Posted by klaatu

Okay, I once caught a fish thiiiiiiiiiiiiiiiiiiiiiiissssssss big. I'd like a less than 2 1/2hr burn and not drop under 300F for atleast 5hrs. So , how much cladding above and perlcrete under ? I'm just trying to get in the ballpark.
Rick,

I think the 2 ovens you are experienced with are not performing ideally - many have posted here with experiences of faster than 2 1/2 hour burns and high temps the next morning (I guess it depends how long you sleep in though). As a counter example, my father built an oven with little insulation and the flu in the dome rather than in front of the door area. His oven takes 3 hours with an aggressive fire to bring to heat, and still only reached 3-4 minute pizza temps rather than about 2" with my better insulated oven. Keep to 1" cladding maximum and insulate well - you'll see.

Marc