Alan Scott oven in sydney

[chubbybones]

Hi guys,
I just found you guys after looking for information for my oven build.I've been meaning to make an oven for a while now but never had the opportunity.We moved to a new place and can now build one.We dont want to take up a lot of space both with the footprint of the oven and the airspace it will occupy above so im going to try and keep it relatively low (as much as feasibly possible).

The concrete block dimensions will be 1350mm(w) x 1500mm(d).I will probably end up with an oven which is like 700mm x 800mm in size.So not really huge but big enough i think for a couple of pizza's.I also want to be able to make breads which is probably why i went for the Scott design.From what i can gather the extra mass/insulation makes for the perfect temps for breads in a retained heating environment.I understand that this particular design is not endorsed on this forum as they have and sell their own variety here so if im not supposed to be here,i apologise in advance.

I have just broken ground and poured a small slab 100mm thick (slightly thicker around the edges).My first issue was that my slab had to start higher than it should be because i have water pipes to the house which run past quite high.This is going to make the opening under the oven very small when i build the concrete blocks up to slab level.But i guess i can live with that.
Anyways i hope to be able to post progress of my oven here in due course.
Thanks,John.

[chubbybones]

Re: Alan Scott oven in sydney

Got some blockwork done today.Starting to get an idea of the bulk of it all but a long way to go still.Next im going to start building a platform inside the blockwork to support the insulation that will sit under the hearth slab.

I need to start ordering some materials aswell like the vermiculite insulation and of course the hearth fire bricks and refractory cement.If anyone has any recommendations in sydney i'd appreciate that otherwise i was going to get them from " Field Furnace Refractories" or "Sydney fire bricks".
Ciao for now.
John.

[brickie in oz]

Re: Alan Scott oven in sydney

You seriously need to rethink the Alan Scott oven idea, unless you have a forest of firewood to burn that is.

[chubbybones]

Re: Alan Scott oven in sydney

You seriously need to rethink the Alan Scott oven idea, unless you have a forest of firewood to burn that is.

Hi there Al,
You are having me worried now
Is it not pretty similar to other ovens using insulation?
I actually intend on reducing the thickness of insulation recommended in the book all around the oven dome and under the hearth.
For the bottom ill have the hearth firebricks on edge (110mm) sitting on a hearth slab (75mm) which in turn sits on vermiculite mix (50mm)
The dome will consist of the same brick width (110mm) + concrete cladding (50mm) with a final vermiculite mix (50mm).
So thats 235mm (9.5 inches) on the bottom and 220mm around sides and back(9 inches).
Oh well i better start making friends with a firewood supplier

[brickie in oz]

Re: Alan Scott oven in sydney

Its fine if you have a bakery that fires every day, but for home use forget it.

[brickie in oz]

Re: Alan Scott oven in sydney

I actually intend on reducing the thickness of insulation recommended in the book all around the oven dome and under the hearth.

I think you have thermal mass and insulation mixed up

[brissie]

Re: Alan Scott oven in sydney

I think you have thermal mass and insulation mixed up

I am with you on that brickie. 50mm insulation all around is not much at all. I have been adding extra insulation just so I can cook for an additional day or perhaps two...

I don't have experience yet but by all indicators that additional thermal mass, bricks and concrete is going to take some fire to heat to pizza temperature.

[chubbybones]

Re: Alan Scott oven in sydney

Ok,so do you guys suggest i decrease the thermal mass and increase the insulation?

[brissie]

Re: Alan Scott oven in sydney

Ok,so do you guys suggest i decrease the thermal mass and increase the insulation?

Having not completed my oven, but doing the research, and knowing basic physics, I have come to the conclusion if you want to save energy (wood) and have quick heat up times ~ 1 hour, you need good insulation and not as much thermal mass.

Generally to get to this point, many people use a minimum of 50mm ceramic fibre + more vermiculite concrete insulation, if you have space for the extra padding. Wall thickness is half a brick, or 50 to 80mm castable for the dome. 50mm calsil board under the hearth bricks. Calsil board can be substituted with vermiculite concrete. However if bread is the main aim then more mass is recommended.

It really depend on what you want, but I would not skimp on insulation, and remember that the more thermal mass, it will take longer to heat but allow you to bake for a longer time. In a home situation to much mass may be a liability.

[chubbybones]

Re: Alan Scott oven in sydney

Hi brissie,
I think if i go for a thermal mass of 176mm (7'') in the floor( firebrick+hearth slab) and 126mm (5'') in the walls(red brick + concrete cladding) , it should suffice.As for insulation , i will probably now end up putting 100mm (4'') under the hearth slab and 75mm (3") around the walls.
Im not really too fussed if i end up using more fuel to get it going.

Cheers,John.

[brickie in oz]

Re: Alan Scott oven in sydney

Hi brissie,
I think if i go for a thermal mass of 176mm (7'') in the floor( firebrick+hearth slab) and 126mm (5'') in the walls(red brick + concrete cladding) , it should suffice.As for insulation , i will probably now end up putting 100mm (4'') under the hearth slab and 75mm (3") around the walls.
Im not really too fussed if i end up using more fuel to get it going.

Cheers,John.

I doubt it will ever get hot enough for pizza if that is what your aim is.
There have been lots of threads started by ppl who have built the AS oven and they all complain that it never gets hot enough.

Anyway, build it and report back.

[cobblerdave]

Re: Alan Scott oven in sydney

I doubt it will ever get hot enough for pizza if that is what your aim is.
There have been lots of threads started by ppl who have built the AS oven and they all complain that it never gets hot enough.

Anyway, build it and report back.

Gudday
Al build an Allan Scott / Allan watt (aussie) inspired oven.
Then rebuilt it .... Check the link on the bottom of his posts.
It's not a true "forno" oven. Lower mass more insulation,though.
Regards dave

[Polo]

Re: Alan Scott oven in sydney

I'll give the straight scoop on an Alan Scott oven that is built from his plans.

It will indeed take more wood to reach pizza temperatures, but it will get there. The "forest of wood" analogy is a poor one. As a matter of fact I would dare say that one who fires their pompeii oven three times a week to make a few pizzas is deforesting the planet much more quickly than I am firing it once and baking all week.

My oven is a 32"x38" hearth dimension oven with 7" of mass all around. It will take me 5 hours of firing to reach 800 - 900 F (that is a temperature read at 1" into the hearth brick). It takes longer to saturate the oven to 4" deep, but that is not necessary for baking a few pizzas.

I use my oven prety much exclusively for bread baking and the amount of heat it stores is incredible. If you are building the oven to make a few pizzas once a week, I agree that a higher mass oven is a waste. If you are planning on using the retained heat to bake and cook throughout the week, then this is the right choice. If I bake on Sunday morning (550 F) the oven is still at 110 F when I light the fire to bake a week later. (saturated temperatures for my oven are read at 4" into the masonry)

[chubbybones]

Re: Alan Scott oven in sydney

Well i had a good talking to by a friend who is an expert in this field and i will definately be changing things up somewhat.I'll be going for a hybrid version of the original design.Barrel vault type oven with approx. 75mm thermal mass all round and close to 150mm of insulation.Unlike Alan scotts design i will be putting the insulation over the hearth slab not under it,meaning i no longer need to design a suspended type hearth slab,it could just sit of the existing concrete blockwork.I will actually probably end up with a slightly bigger oven internally overall so thats also good.

Thanks to all who pushed me to revise my original idea.

Polo,i definately see the advantages of an oven like yours and like you say its also very efficient in the fact you need not fire it as often but i dont think ill be needing to be cooking throughout the week.I see myself as a weekend cook for when people come over etc.So i think i quicker fire up time and still a decent amount of retained heat time will be ideal for my purposes.

I'll keep you guys updated.
Cheers,John.

[Laurentius]

Re: Alan Scott oven in sydney

I'll give the straight scoop on an Alan Scott oven that is built from his plans.

It will indeed take more wood to reach pizza temperatures, but it will get there. The "forest of wood" analogy is a poor one. As a matter of fact I would dare say that one who fires their pompeii oven three times a week to make a few pizzas is deforesting the planet much more quickly than I am firing it once and baking all week.

My oven is a 32"x38" hearth dimension oven with 7" of mass all around. It will take me 5 hours of firing to reach 800 - 900 F (that is a temperature read at 1" into the hearth brick). It takes longer to saturate the oven to 4" deep, but that is not necessary for baking a few pizzas.

I use my oven prety much exclusively for bread baking and the amount of heat it stores is incredible. If you are building the oven to make a few pizzas once a week, I agree that a higher mass oven is a waste. If you are planning on using the retained heat to bake and cook throughout the week, then this is the right choice. If I bake on Sunday morning (550 F) the oven is still at 110 F when I light the fire to bake a week later. (saturated temperatures for my oven are read at 4" into the masonry)

Hi Polo,

Most of our ovens are on par with your, especially those of us who choose ceramic fiber boards and blankets, and didn't build primarily for pizzas.