#1  
Old 02-16-2008, 11:24 PM
Il Pizzaiolo
 
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Location: Mishigame & Iberia
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Default Hearth Height and operator ratio science!

WFO experts, another post made me wonder what a standard height for a WFO hearth should be. (Obviously a custom height shoulld be better for individual bakers based on their own height.)

My hearth is at 97cm or 38.2 inches and was predetermined by the manufacturer. I did not raise or lower it but I could have.

I'm 6 feet tall so the hearth to height ratio is 38.2 / 72 or .53

I have never felt my hearth needed to be higher or lower for me. I tend to look down on the pizzas cooking. But when I consciously look at it now, I think it could have been higher....maybe more chest level than waist. What do you think?

Want to compare your height and ratio?

James, what's considered standard?
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  #2  
Old 02-17-2008, 07:31 AM
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Posts: 306
Default Re: Hearth Height and operator ratio science!

See the following table

Oven area versus open area

Naples residential oven
Internal H Area Opening W Opening H Area Ratio
31.4 14.9 469.5 17.3 9.8 169.9 0.36
35.4 16.5 583.8 18.5 9.8 181.5 0.31
39.3 15.3 602.4 18.9 11.8 222.4 0.37
43.2 15.3 662.6 18.9 11.8 222.4 0.34

Tuscan residential oven (higher)
Internal H Area Opening W Opening H Area Ratio
35.4 19.7 695.0 18.9 12.2 229.8 0.33
39.3 19.7 772.2 18.9 12.6 237.2 0.31
43.2 19.7 849.5 18.9 12.6 237.2 0.28
47.2 22.0 1037.9 18.9 12.6 237.2 0.23

Commercial oven
Internal H Area Opening W Opening H Area Ratio
43.2 20.0 866.5 21.6 13.8 297.3 0.34
47.2 22.0 1037.9 21.6 13.8 297.3 0.29
51.1 23.6 1204.7 21.6 13.8 297.3 0.25
57.0 25.9 1478.1 21.6 13.8 297.3 0.20
62.9 24.8 1556.8 21.6 13.8 297.3 0.19
72.7 25.5 1857.2 21.6 13.8 297.3 0.16

Luis
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Old 02-17-2008, 07:45 AM
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Default Re: Hearth Height and operator ratio science!

There was a long time I posted the lines below.
Since I have in a hurry just now, please let me to paste these lines without edition.
I hope this could help

As empirical as the numerical dome door relationships are, there is a reason behind them.
This is based and referred to a flux (or flow) gases behavior.
Shortly speaking, when the gases in the oven are getting hot, these gases are driving in a turbulent pattern, from the ignited wood in the floor to the oven ceiling. These hot gases fill the under ceiling space pushing down and out the cold gases, until reaching the upper door aperture, leaving the oven in a disordered cloud type pattern.
The following hot gases coming to the ceiling found a hotter environment that the first ones. As is not to easy to push this gases right down, a path coming from the fire on the side of the oven, bordering the ceiling and the upper side of the door is formed and the gasses goes down to the upper edge of the door and straight up from there.
The fresh air enters by the lower edge of the door directly to the embers on fire.
There is an ordered path now, growing as the fire increase, the flames are attracted by this ‘suction path’ and it is easy to be surprised by the straight fire dancing.
In regime, the fresh air is incoming by the down space of the door and the hot gases are going out by the upper edge of the door to the vent area and chimney.
If the door is too high, the hot gases coming from the fired wood, will escape right before reach the upper dome and an ‘isolate’ layer of cold air will be between the hot gases and the ceiling. More fuel to reach the desired temperature.
As indirectly consequence of the door being too high, more heat will escape when baking.
If the door is too low (always in relationship with the dome height), the hot gases will separate of the ceiling edge before reaching the upper edge of the door, which cause severe turbulence just in front of the door. The air rarify, the flow path is discontinued and will be hard to the hot gases to go out. Returning gases have little oxygen. The fire in the woods will be suffocated. More fuel and changing in the embers position to reach the desired temperature.
Conclusion: In my opinion, could be better be wrong having a higher than a lower door.
In practice, the two examples above are a little extremes, and I am pretty sure that plus or minus 5% of difference from the 64% calculated will not create bigger problems that spending a little more fuel (wood).
Otherwise, the Napolitano pizza ovens have a relationship of H= d/3.4. And they are the best to baking pizza. H being the dome high and d being the dome diameter.
If thinking about this, could be a better solution for you to maintain the Door/Dome relationship in 0.64 by flattening the upper part of your dome.
Better for pizza, faster to heat and less fuel to spend on it.


Luis
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Old 02-17-2008, 07:51 AM
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Default Re: Hearth Height and operator ratio science!

Interesting question, Jim.

My hearth is 107 cm high (a lot higher than planned, because I forgot to allow for insulation ) and I'm quite small (158.5 cm) so that gives a ratio of 0.68.

I was worried it would be too high to build fires comfortably and thought I'd put in a step if necessary, but it turns out that it is a really comfortable hight for cooking. I certainly wouldn't want it lower if I did it over again.

So to get the same relative height, your hearth would have to be 48.6 inches (or 123 cm), right?

Have we got any phisiotherapists on the forum who could tell us what the ideal height should be?
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Old 02-17-2008, 09:23 AM
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Default Re: Hearth Height and operator ratio science!

Having suffered through the very low countertops and sinks in Japan (not to mention the low doors), I intentionally tried to go a little high, so I wouldn't have to be bending over to see in the oven.

I'm 73 inches tall, the hearth is 40.5 inches gives me a ratio of .555, so not much different than yours Jim. It seems to be a good height for me.
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Old 02-17-2008, 11:52 AM
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Default Re: Hearth Height and operator ratio science!

You build your oven from scratch, you learn to cook in it, you learn all its quirks and know its every nook and cranny - stikes me you'll always think your own oven is the ideal height.
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Old 02-17-2008, 11:53 AM
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Default Re: Hearth Height and operator ratio science!

Well said Frances!
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Old 02-17-2008, 01:02 PM
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Default Re: Hearth Height and operator ratio science!

Quote:
Originally Posted by Frances View Post
You build your oven from scratch, you learn to cook in it, you learn all its quirks and know its every nook and cranny - stikes me you'll always think your own oven is the ideal height.
Nah...

Mine's a little low!
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Old 02-17-2008, 01:34 PM
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Default Re: Hearth Height and operator ratio science!

Oven height ratios are directly related to age and inversely related to the time since completion.

The older you are, the more you complain about the oven height ( or lack thereof)

You always like your oven height right after you finish it. As time goes on, you become more convinced another height is better.

Bruce
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Old 02-17-2008, 10:29 PM
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Default Re: Hearth Height and operator ratio science!

Regardless, after standing in front of my oven tonight cooking pizzas and contemplating this question, the important thing is to have room to back up enough to see into the oven without bending over.
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