Overkill?

[PerryPizza]

I've just laid my 3" thick brick floor and I can't help thinking it's just too much thermal mass for what I'm going to use it for, cooking 1 - 6 pizzas and a baguette every now & then. For me I'd rather have an oven which heats up quickly than one capable of cooking 20+ pizzas in one firing.
Another thing is my oven is very small (31") due to space limitations.
I've got enough 2" thick bricks to re-do the floor tomorrow (and they're new bricks) - anyone think I should, or will I end up regretting losing that extra thermal mass?... surely 2" is plenty thick enough for what I need???

[KraemerBAC]

Re: Overkill?

Perry,

Based on everything I have read so far, and I am by no means an expert...and somebody will probably contradict me, it doesn't seem like you are adding that much extra mass for the size oven you are building hence the heat up time shouldn't be increased by that much. You will probably hold heat longer though.

Peter

[DrakeRemoray]

Re: Overkill?

I will jump in and contradict Peter.

You don't need extra mass in the floor and adding extra mass in the floor makes keeping the floor hot during cooking pizza more challenging. When people do add extra mass, they tend to add it in the dome (as I did). If it is not a big deal, I would use the thinner bricks for the floor.

Drake

[KraemerBAC]

Re: Overkill?

All righty then...xtra mass in the floor bad, extra mass in the dome good...I stand corrected and my apologies

Peter

[DrakeRemoray]

Re: Overkill?

I think for most people the extra mass in the dome is a no-no too. I wanted to bake bread and started with a barrel vault design, so for me it makes sense. If you are going to bake fewer than 15lbs of bread (a totally arbitrary number) then you will not need extra mass. I acutally spend a lot of time waiting for my oven to cool enough so I can bake.

Drake

[dmun]

Re: Overkill?

Yes, this community came to the one-brick-thick floor by trial and error, at the cost of some ovens that were very inefficient to heat. The first design was for the insulation below the support slab as in the Scott oven, then a slug of concrete was put below the floor, inset in the vermiculite concrete, the so-called island hearth. Finally it was determined the one layer of flat laid bricks was just right for the floor. I'm glad that I spent a year reading and planning before making that decision: 2.25 inch thick floor is just right for me.

[Matt916]

Re: Overkill?

I'm still trying to understand the thermodynamics of wood-fired ovens, so sorry if there is an obvious answer to this question, but why is too much mass in either the dome or the floor a bad thing? I thought that more mass means a hotter oven that holds heat in for longer...which i thought was a good thing for food.

[james]

Re: Overkill?

There are some great threads in the forum to read, and a page on FB.com. Why don't you read this as a start:

Thermal Mass Primer

It should make some intuitive sense and keep your creative thoughts flowing. I can add one other thing. My growing experience with the Primavera ovens (which are a little thinner than the FB precast ovens) has reinforced for me that the precast ovens have more than enough mass for baking and roasting -- plus the faster heat up times and the ability to maintain 800?F+ temperatures for baking Pizza Napoletana make these ovens and the Pompeii oven with a 2.5" floor and a 3-4.5" dome perfect!
James

[DrakeRemoray]

Re: Overkill?

My thoughts
1) More mass takes longer to heat up. More wood, more time.
2) It is not necessary for home or most commercial uses. The refractory ovens that FB tells have a thinner floor than a brick on it's side.
3) More mass makes it more sluggish as well, slower to cool when you want it to cool and slower to heat the floor when you need it to recharge between pizzas.

[dmun]

Re: Overkill?

Firing up a high-mass oven is an all afternoon project. That's fine if you're going to use the heat for multiple batch bread bakes, but most of us want to fire up the oven for a quick pizza bake. That's where the lower mass ovens come in. The fact that it only uses a couple of armloads of wood is a factor too.

[Les]

Re: Overkill?

I've just laid my 3" thick brick floor and I can't help thinking it's just too much thermal mass for what I'm going to use it for

Perry, most of our floors are 2.5 inches thick - 3 inches is just 20% more. I don't see this as the end of the world, and personally, I wouldn't change it. In fact, I wished I had just a little more mass on the floor. All things being equal, 20% more wood to bring it to heat would be something less than 2 sticks and less then 1/2 hour of time. The time is a huge variable - if you go nuclear, it will take considerable less. Question, where did you get 3 inch brick (or did you rip the standard?)

Les...

[james]

Re: Overkill?

Nice point Les.

If you have the bricks and have done the work, a 3" floor isn't a disaster. That said, it's a real bear keeping a thick oven floor hot enough to bake serious pizza. And even if you can make it work, it takes a lot of the fun out of the evening.

I know I'm a stuck record on this one, but I think it's important. The FB Modena commercial Italian pizza ovens are designed for 10+ years of high throughput restaurant pizza baking, they are the state-of-the-art, very popular in Italian pizzerias, and they have a 2 3/4" cooking floor.

It worries me that too many builders overlook this.
James

[PerryPizza]

Re: Overkill?

Question, where did you get 3 inch brick (or did you rip the standard?)

Les...

I got them from David Reekie, who I think got them from Aureole...

I'm going to re-do the floor with the thinner brick - it's laid on a dry mix of fireclay & sand so it isn't a huge problem to change it. The surface on the new bricks is much rougher than the ones I'm replacing (it looks as if the 'grain' of the brick runs through it like in a slice of bread) but I don't think this will be a problem, especially as I like a bit of char on my pizza base. Cosmetically the smooth bricks do look a bit nicer though...

Just looking at the 3" floor I can see it will take a very long time to heat up, I honestly think the 2" one will be more than enough, especially after the comments in the thread - gloves are on & the sun is up, time to crack on!