Thermal mass across whole floor or biased centrally ?

[Tank]

Re: Thermal mass across whole floor or biased centrally ?

if the bricks weren't $6 each making the build 3x the cost what these alternative designs

I have often thought it would be worth importing 1/2 a container of them to sell down here. You could make some $$$$ undercutting place makers etc.

[Tscarborough]

Re: Thermal mass across whole floor or biased centrally ?

Basically, the old method of making bricks is the same as the modern way of making fire bricks, but not modern brick. That is, they are drypack pressed not wet extruded like modern brick. They will hold about the same amount of heat, but the firebrick ARE more durable, and have slightly better physical characteristics (very accurate sizing).

In some parts of the world, old common solids are not very common, or if available they are almost as expensive as FB and pretty beat up. In this area, we also have a brick industry that makes brick by hand, wetpack in wood molds and fires them at relatively low temperature. These will work for an oven as well, but they erode quickly, so even though they are dirt cheap, I do not recommend them.

[uk_exile]

Re: Thermal mass across whole floor or biased centrally ?

So old red house brick will be ok but they just won't store as much heat as true fire bricks. Correct ?
Seems most builders on FB use fire bricks. Is that a bit over the top for a 4 person family domestic use ? i.e. has excess storage

[Tscarborough]

Re: Thermal mass across whole floor or biased centrally ?

Insulating refractory is used in situations where you want to store a liquid or gaseous material with minimal energy input, i.e. a kiln or a boiler. Firebrick are used to store heat, i.e. an oven.

[Laku]

Re: Thermal mass across whole floor or biased centrally ?

Roman ovens were made of "normal" red clay bricks. They are still around.

[uk_exile]

Re: Thermal mass across whole floor or biased centrally ?

Oh, that's quite different than I thought. I may need to recost it all as will be able to get recycled red house bricks. Probably still more expensive than new house brick but will be less than new or used fire bricks. Factor may become increased insulation needs & higher wood cost vs the insulated brick less insulation design.

[Tscarborough]

Re: Thermal mass across whole floor or biased centrally ?

"Spall" is the correct term, and if they are old solid brick, they will not spall under normal conditions. They will eventually erode (similar to spalling, but at a microscopic scale), but that is a long slow process.

[uk_exile]

Re: Thermal mass across whole floor or biased centrally ?

I didn't think common bricks could be used. I read somewhere that when heated they shoot little bits of brick off their surface & hence ruin the food. Splay is the term I think

[Tscarborough]

Re: Thermal mass across whole floor or biased centrally ?

I can't believe that you can not find 200 solid common used brick for less than 6 bucks ea. Use them for the dome and buy enough fire brick for the floor, and you are gold.

[uk_exile]

Re: Thermal mass across whole floor or biased centrally ?

Get the plans, build your own oven.

Thanks however I have the Pompei plans, they're the ones that really sparked my interest a couple of years ago and I would just build off them if the bricks weren't $6 each making the build 3x the cost what these alternative designs are.

I'm not wanting to compare this kit's performance to a full on high mass pompeii type design as I know it won't be as 'good'. However I'm willing to sacrifice some aspects such as really long slow cooking in favour of quicker heat up, less wood knowing in return we'll use it more often & will save money both building & operating it. I'm trying to compare it's performance to a steel box 'pizza' oven that sells for similar money (or often more).
Wood Fired Pizza Oven | Trade Me

Is the fozmex kit design 'good' enough ? Can it be 'improved' by adding a little more mass ?

[brickie in oz]

Re: Thermal mass across whole floor or biased centrally ?

Here's the info I received re cooking tile.
Heat Sink Tile
The heat sink tile is an additional, unique feature of the Deco Wood Fired Oven.

Rubbish, this is how all wood ovens work.

The tile is supplied in x 2 monolithic halves and has a hard, ceramic-like cooking surface. It has also been designed to absorb and retain intense heat, releasing it slowly after the combustion process is spent. It is akin to cooking on stone.

Like a normal wood oven

The tile is manufactured from a composition which has a very high thermal-mass.

Like a normal Aluminium oxide firebrick you mean?
The same stuff that gives you cancer according to their website.

Because of the cyclic changes in temperatures that the tile is subject to (ie. heating/cooling), and that it absorbs moisture from the atmosphere in between oven firings (ie. water turns to steam and can’t escape),

Rubbish, most water in an oven turns to steam and burns off, its the quick generation of steam in the refractories that cracks them.

The tile surface is covered with a thin film of beeswax to assist in curing.

Which will burn off at the slightest hint of a flame.



The crap that people spin to sell stuff is just unbelievable.
Get the plans, build your own oven.

[uk_exile]

Re: Thermal mass across whole floor or biased centrally ?

Thanks Tscarborough, maybe I'll just go fo the kitset exactly as supplied as aim is for convenient use.

Here's the info I received re cooking tile.
Heat Sink Tile
The heat sink tile is an additional, unique feature of the Deco Wood Fired Oven. The tile is supplied in x 2 monolithic halves and has a hard, ceramic-like cooking surface. It has also been designed to absorb and retain intense heat, releasing it slowly after the combustion process is spent. It is akin to cooking on stone.
The tile is manufactured from a composition which has a very high thermal-mass. Because of the cyclic changes in temperatures that the tile is subject to (ie. heating/cooling), and that it absorbs moisture from the atmosphere in between oven firings (ie. water turns to steam and can’t escape), it is highly likely the tiles will develop surface fissures and may occasionally, fracture. Any such events will in no way affect the performance of the files and/or, oven. We have made the tile a few mm thicker than the insulation tiles for greater heat retention, and for ease of clearing ash. The tile surface is covered with a thin film of beeswax to assist in curing.

[Tscarborough]

Re: Thermal mass across whole floor or biased centrally ?

The floor is the hardest area to fire, and for a low use pizza oven, the thermal mass should be minimal, 2.5" bricks laid as pavers for the hearth, with good insulation will work better than localized mass or thick floors.

[uk_exile]

Re: Thermal mass across whole floor or biased centrally ?

Clever idea ! I don’t know what the tile is made of. I’ll ask

[ATK406]

Re: Thermal mass across whole floor or biased centrally ?

Sounds reasonable. That would also increase the size of your cooking surface. You might even be able to cut the third layer of cooking tiles in such a way that you could remove them if they slow down your heat-up time too much. And you could put them back in when you think you need more thermal mass. May be a bit of a pain but might give you the flexibility you are looking for.

What is the cooking tile made of? Is it ceramic? If so, that might be hard to cut.

AT